700R92011
                DETERMINATION OF RATES OF  REACTION

                IN THE GAS-PHASE IN THE TROPOSPHERE


                       THEORY AND PRACTICE
      3.   Rate of Indirect Photoreaction:  Technical Support
   Document for Test  Guideline  796.3900.  Structure/Reactivity
        Relationships for Estimating the Second-Order Rate
              Constant  for the Reaction of an Organic
\s                 Chemical with Hydroxyl Radicals
                                by

                            Asa Leifer
               U.S. ENVIRONMENTAL PROTECTION AGENCY
                    OFFICE OF TOXIC SUBSTANCES
                       WASHINGTON,  DC  20460
     CJ

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                        Table of Contents
Abstract
I.
II.

II. A.
II. B.
III.
III. A.
III. A.I.
III. A. 2.
III. A. 2. a.
III. A. 2. a. i.
III. A. 2. a. ii.
III. A. 2. a. ill.
III. A. 2. b.
III. A. 2. c.
III. A. 2. d.
III. A. 2. e.

Introduction
Kinetics of the Reaction of a Chemical with
Hydroxyl Radicals in the Gas-Phase in the
Troposphere
Rate Laws
Effect of Temperature on Rate
Structure/Reactivity Relationships for
Estimating the Second-Order Rate Constant
(kOH) for the Reaction of Hydroxyl Radicals
with Organic Chemicals in the Gas-Phase
H-Atom Abstraction from C-H and 0-H Groups
and the Estimation of k0jj
Formulation of the Structure/Reactivity
Relationships
Estimation of kOH for Several Classes
of Organic Chemicals at 298 K and a
Comparison of These Results with the
Experimental Data
Alkanes
Acyclic Alkanes
Cyclic Alkanes
All Alkanes (Acyclic and Cyclic)
Haloalkanes
Carbonyl Compounds: Aldehydes, Ketones,
a-Dicarbonyls, Acid Chlorides, and Esters
Alcohols, Glycols, and Ethers
Nitrates and Nitriles
xii
1

5
5
7
9
10
10
24
24
24
28
30
30
34
41
49
III.A.2.f.     Olefins, Diolefins, Alkynes,  and Aromatic
               Compounds                                       5 3
                               -11-

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                    Table of Contents (cont.)
III.A.3.       Summary                                         54

III.B.         Addition of Hydroxyl Radicals to Olefinic,
               Conjugated Diolefinic, 1,2-Diolefinic
               Compounds and Alkynes and the Estimation
               of kOH                                          58

III.B.I.       Formulation of the Structure/Reactivity
               Relationships                                   58

III.B.2.       Estimation of kOH for Several Classes of
               Chemicals at 298 K and a Comparison of
               These Results with the Experimental Data        67

III.B.2.a.     Unsubstituted Alkenes                           67

IZI.B.2.b.     Substituted Alkenes                             73

III.B.2.C.     Conjugated Dialkenes                            76

III.B.2.d.     Alkynes. and 1,2-Dialkenes (Allenes)             79

III.B.3.       Summary                                         81

III.C.         Reaction of Hydroxyl Radicals with
               Organic Chemicals Containing Sulfur,
               Nitrogen, and Phosphorus Functional
               Groups and the Estimation of kOH                83

III.C.I.       Reaction of Hydroxyl Radicals with Thiols,
               Sulfides, and Oisulfides                        83

III.C.I.a.     Formulation of the Structure/Reactivity
               Relationships                                   83

Ill.C.l.b.     Estimation of kOH at 298 K and a Comparison
               of These Results with the Experimental Data     85

III.C.2.       Reaction of Hydroxyl Radicals with Aliphatic
               Amines, Hydrazines, N-Nitrosamines,
               N-Hydroxylamines, and N-Nitramines              89

III.C.2.a.     Formulation of the Structure/Reactivity
               Relationships                                   89

III.C.2.b.     Estimation of kOH at 298 K and the
               Comparison of these Results with
               Experimental Data                               92
                              -iii-

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                    Table of Contents (cont.)


III.C.3.       Reaction of Hydroxyl Radicals with
               Organophosphorus Compounds                      95

III.C.3. a.     Formulation of the Structure/Reactivity
               Relationships                                   95

III.C.3.b.     Estimation of kOH at 298 K and the
               Comparison of These Results with
               Experimental Data                               98

III.C.4.       Summary                                        102

III.D.         Reaction of Hydroxyl Radicals with Aromatic
               Compounds and the Estimation of XQJJ            105
III. D.I.       Formulation of the Structure/Reactivity
               Relationships                                  105

III.D. 2.       Estimation of kOH for Several Classes of
               Aromatic Compounds at 298 K and the
               Comparison of These Results with the
               Experimental Data                              113

III.D. 2. a.     Benzene and Biphenyl                           113

III.D.2.b.     Alkylbenzenes                                  122

III.D.2.C      Alkenylbenzenes                                123

III.D.2.d.     Halogenated Benzenes                           124

III.D.2.e.     Haloalkylbenzenes                              125

III.D.2.f.     Monochlorobiphenyls                            126

III.D.2.g.     Hydroxybenzenes                                127

III.D.2.h.     Nitrobenzenes                                  128

III.D.2.i.     Aminobenzenes                                  123

III.D.2.J.     Additional Substituted Benzenes                129

1 1 1 . D . 2 . k .     Po lyar omat ic Hydrocarbons                      1 3 o

III.D. 3.       Summary                                        132
                               -IV-

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                    Table of Contents (cont.)


III.E.         Summary of Results for the Estimation of
               kon for All Chemicals in a Number of Classes
               of Chemicals by the Structure/Reactivity
               Relationships of Atkinson of the University
               of California/Riverside                        137

IV.            Illustrative Examples:  Use of the Structure/
               Reactivity Relationships of Atkinson to
               Estimate the Second-Order Rate Constant
               (kOH) for the Reaction of Hydroxyl Radicals
               with Organic Chemicals in the Gas-Phase
               at 298 K in Air at Atmospheric Pressure        139

IV.A.          Alkanes (Acyclic and Cyclic)                   144

IV.A.I.        2-Methylpentane                                144

IV.A.2.        Bicyclof3.3.0]octane                           145

IV.A.3.        Isopropylcyclopropane                          145

IV.B.          Haloalkanes                                    146

IV.B.I.        Difluoromethane                                146

IV.B.2.        1,1-Difluoroethane                             147

IV.C.          Carbony1 Compounds                             147

IV.C.I.        Butanal                                        147

IV.C.2.        Trichloroacetaldehyde                          148

IV.C.3.        2-Pentanone                                    148

IV.C.4.        Cyclobutanone                                  149

IV.C.5.        Methyl Glyoxal                                 149

IV.C.6.        Acetyl Chloride                                150

IV.C.7.        n-Propyl Acetate                               150

IV.D.          Alcohols and Glycols                           150

IV.D.I.        2-Propanol                                     150

IV.D.2.        1,2-Ethanediol                                 151
                               -v-

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Table of Contents (cont.)
IV. E.
IV. E.I.
IV. E. 2.
IV. E. 3.
IV. E. 4.
IV. F.
IV. F.I.
IV. G.
IV. G.I.
IV. H.
IV. H.I.
IV. H. 2.
IV. H. 3.
IV. I.
IV. I.I.
IV. I. 2.
IV. I. 3.
IV. I. 4.
IV. I. 5.
IV. I. 6.
IV. J.
IV. J.I.
IV. J. 2.
IV. J. 3.
Ethers (Acyclic and Cyclic)
2-Ethoxyethanol
Diethoxymethane
1 , 2-Epoxybutane
Oxepane (Hexamethylene Oxide)
Nitrates
3-Methyl-2-pentyl Nitrate
Nitriles
Propionitrile
Unsubstituted Alkenes (Acyclic and Cyclic)
1-Pentene
1,4-Pentadiene
Bicyclo [2.2.1] -2-heptene
Substituted Alkenes
Vinyl Bromide
trans-2-Butenal ( trans-Crotonaldehyde )
cis-3 -Hexene-2 , 5-dione
fcis-1.2-Diacetylethylene)
Tetrachloroethene
Acrylonitrile
Methyl Ketene
Conjugated Diolefins
cis-1 . 3-Pentadiene
1, 3-Cyclohexadiene
2 , 5-Dimethyl-2 , 4-hexadiene
152
152
153
153
154
154
154
155
155
156
156
157
158
159
159
159
160
161
162
162
163
163
164
165
           -vi-

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                    Table of Contents (cont.)

IV.J.4.        4-Methyl-l,3-pentadiene                        166
IV.K.           Alkynes                                        166
IV.K.I.        1-Butyne                                       166
IV.L.           Allenes                                        167
IV.L.I.        1,2-Pentadiene                                 167
IV.M.           Thiols, Sulfides, and Bisulfides               168
IV.M.I.        2-Methyl-l-propanethiol                        168
IV.M.2.        Tetrahydrothiophene                            169
IV.M.3.        Dimethyl Disulfide                             170
IV.N.           Compounds Containing Nitrogen Functional
                 Groups                                       170
IV.N.I.        Dimethylhydroxyethylamine                      170
IV.N.2.        Dimethyl-N-nitrosamine                         171
IV.N.3.        Methyl Hydrazine                               172
IV.N.4.        Diethyl-N-hydroxylamine                        172
IV.0.           Compounds Containing Phosphorus
                 Functional Groups                            173
IV.0.1.        Triethyl Phosphate                             173
IV.0.2.        0,0-Dimethyl Chlorophosphorothioate            174
IV.0.3.        O,0,N-Trimethylphosphoroamidothioate           174
IV.P.           Aromatic Compounds                             175
IV.P.I.        Toluene                                        175
IV.P.2.        trans-1-Phenyl-l-propene                       177
IV.P.3.        4-Chlorobenzotrifluoride                       178
IV.P.4.        1,2,4-Trichlorobenzene                         179
IV.P.5.        o-Cresol                                       181
                               -vii-

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                    Table of Contents (cont.)
IV.P.6.        Aniline                                        182
IV.P.7.        Hexafluorobenzene                              183
IV.P.8.        2,3-Dihydrobenzofuran                          185
IV.P.9.        3-Chlorobiphenyl                               186
IV.P.10.       1-Methylnaphthalene                            188
IV.P.11.       1,4-Dichloronaphthalene                        190
V.             Tropospheric Half-Life                         190
VI.            Screening-Level Test Guideline:  Estimation
               of kOH and ^(i/2\E for a Chemical (S)
               Produced by Chemical Company X via the
               Estimation Techniques of Atkinson              193
VII.           Mathematical Synopsis of the Structure/
               Reactivity Relationships of Atkinson           198
VIII.          References                                     205
                              -Vlll-

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List of Tables

Table 1.
Table 2.


Table 3.A.



Table 3.B.



Table 4.



Table 5.



Table 6.



Table 7.



Table 8.
Table 9.
Table  10.
Table 11.
Group Rate Constants k and k at 298 K and the
Parameters A" and E'[=E(X)] in Equation 26      17

Substituent Factors F(X) at 298 K and E(X) in
Equation 26 for Various Substituents X          19

Comparison of Experimental and Estimated
Values of k0n for Acyclic Alkanes
at 298 K and the Percent Error                  25

Comparison of Experimental and Estimated
Values of k0H for Cyclic Alkanes at 298 K
and the Percent Error                           29

Comparison of Experimental and Estimated
Values of kOH for Haloalkanes at 298 K and
the Percent Error                               31

Comparison of Experimental and Estimated
Values of k0H for Carbonyl Compounds at
298 K and the Percent Error                     36

Comparison of Experimental and Estimated
Values of kOH at 298 K for Alcohols, Glycols,
and Ethers and the Percent Error                43

Comparison of Experimental and Estimated
Values of kOH at 298 K for Nitrates and
Nitriles and the Percent Error                  50

Summary of the Average Percent Error in kOH
for H-Atom Abstraction from C-H and OH
Groups at 298 K for Chemicals within Several
Classes of Chemicals and for All Chemicals
in These Classes                                55
                      1S
Group Rate Constants ko  in Equation 91
for Hydroxyl Radical Addition to Isolated
Olefinic Groups at 298 K                        63

Substituent Factors C(X) in Equations 91,
92, and 93 for Substituent X on Nonaromatic
Unsaturated Carbon-Carbon Groups at 298 K       64
                      CO
Group Rate Constants ko  in Equation 92
for Hydroxyl Radical Addition to Conjugated
Nonaromatic Functional Groups at 298 K          65
                               -ix-

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Table 12.
Table 13.
Table 14.
Table 15.
Table 16.
Table 17.
Table 18.
Table 19.
Table 20.
Table 21.
Table 22.
Group Rate Constants k,u in Equation 93
for Hydroxyl Radical Addition to Alkynes and
Allenes at 298 K                                68

Comparison of Experimental and Estimated
Values of kOH for Unsubstituted Alkenes
and the Percent Error                           69

Comparison of Experimental and Estimated
Values of kOH for Substituted Alkenes at
298 K and the Percent Error                     74

Comparison of Experimental and Estimated
Values of kOH for Conjugated Acyclic and
Cyclic Dialkenes at 298 K and the Percent
Error                                           77

Comparison of Experimental and Estimated
Values of k0jj fr Alkynes and Allenes           80
at 298 K and the Percent Error

Summary of the Average Percent Error in
kpH for the Reaction of Hydroxyl Radicals
with a Number of Olefins, Conjugated
Diolefins, Allenes, and Alkynes and for
All Chemicals in These Classes                  82

Comparison of Experimental and Estimated
Values of kOH for Alkyl Thiols, Sulfides,
and Disulfides at 298 K and the Percent
Error                                           86

Comparison of Experimental and Estimated
Values of kOH at 298 K for Alkyl Amines,
Hydrazines, and N-Substituted Amines and
the Percent Error                               93
        (
Comparison of Experimental and Estimated
Values of k0H at 298 K for Aliphatic
Compounds Containing Phosphorus Functional
Groups and the Percent Error                    99

Summary of the Average Percent Error on kpH
at 298 K for the Reaction of Hydroxyl Radicals
with a Number of Chemicals in Several Classes
of Chemicals Containing Sulfur, Nitrogen, and
Phosphorous Functional Groups and for All
Chemicals in These Classes of Chemicals        103
Electrophilic Substituent Constants
(a"1" and a+) for a Number of Substituents
  *"      p
               m
                                                             108
                               -x-

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Table 23.    Comparison of Experimental and Estimated
             Values of KQH for Chemicals in Various
             Classes of Aromatic Chemicals at 298 K
             and the Percent Error                           114

Table 24.    Comparison of Experimental and Estimated
             Values of kOH for Fused Ring Polyaromatic
             Hydrocarbons                                    133

Table 25.    Summary of the Average Percent Error in kOH
             at 298 K for a Number of Chemicals in Several
             Classes of Aromatic and Polyaromatic
             Compounds and for All Chemicals in These
             Classes                                         134

Table 26.    Summary of the Statistical Data for All the  .
             Compounds Used in the Analysis of the S/R
             Relationships of Atkinson                       140
                               -xi-

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Abstract
     In support of the Exposure Assessment Branch's  (EAB)
environmental fate programs (U.S. Environmental Protection
Agency, Office of Toxic Substances), Atkinson [1986, 1986a,
1987, 1987b, 1988, 1988a, and Atkinson et al. (1985)] of the
University of California/Riverside, developed structure/
reactivity (S/R) relationships for estimating the second-order
rate constant (k0H) for tne reaction of an organic chemical
with hydroxyl radicals (OH) in the gas-phase in the
troposphere.  These S/R relationships are based on the premise
that several separate OH radical reaction pathways occur and
they can be treated individually.  These reaction pathways are:

     (1)  H-atom abstraction by OH radicals from C-H groups in
          alkanes, ethers, carbonyls, and other saturated
          organics; and from C-H groups in unsaturated carbon-
          carbon groups such as in alkenes, dialkenes, alkynes,
          and aromatic compounds;

     (2)  H-atom abstraction by OH radicals from hydroxyl
          functional groups;
     (3)  OH radical addition to nonaromatic unsaturated
          carbon-carbon functional groups;
     (4)  OH radical interaction with nitrogen, sulfur, and
          phosphorus functional groups; and
                             -xii-

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     (5)  OH radical addition to aromatic and polyaromatic
          rings.
The total OH radical rate constant, kOH (cm3molecule""1s~1) , is
then the sum of the rate constants for each of these reaction
pathways.
     This report gives a detailed discussion of the development
of the S/R relationships of Atkinson.  All pertinent parameters
for estimating k0n are summarized in several tables in this
report.  For the reader's convenience, a mathematical synopsis of
the S/R relationships of Atkinson is given at the end of the
report  (Section VII).
      These S/R relationships were used to estimate kOH at 298 K
of 405 organic chemicals covering a wide variety of chemical
classes.  These chemical classes were:  alkanes (acyclic and
cyclic); haloalkanes; carbonyl compounds such as aldehydes,
ketones, esters, etc.;  ot-dicarbonyls; alcohols and glycols;
ethers  (acyclic and cyclic); nitrates; nitriles; alkenes and
dialkenes  (both conjugated  and unconjugated); ketenes; alkynes;
1,2-dienes  (allenes); thiols; sulfides (acyclic and cyclic);
disulfides; amines; hydrazines; N-substituted amines  (such as
N-nitroso, N-hydroxyl, and  N-nitro); alkyl phosphates/
thiophosphates; dialkyl chlorophosphorothionates; alkyl
phosphoroamidates/phosphorothioamidates; benzene, biphenyl, alkyl
and alkenyl benzenes; halogenated benzenes and haloalkyl
benzenes; monochlorobiphenyls; hydroxy-, niro-, amino-, methoxy-,
and cyanobenzenes;  aromatic aldehydes; polyaromatic hydrocarbons;
                              -xiii-

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and other aromatic compounds.  This report lists the experimental
kOH data for each of the 405 compounds and compares the estimated
values with the experimental values (Percent Error).  Of the 405
chemicals, 20 had a percent error greater than +100 and were
omitted in the analyses.  For the remaining 385 chemicals, the
average percent error ranged from +21 to -19 which is very good
to excellent.  One hundred fifty-four chemicals were not used by
Atkinson to derive the parameters in the S/R relationships and,
therefore, were good candidates to test the validity of these
relationships.  The average percent error of these 154 chemicals
ranged from +24 to -20 which ranged from very good to excellent,
thereby confirming these S/R relationships.  However, a few of
the classes had a minimum number of chemicals so that more
experimental kOH data are needed for additional chemicals in
these classes to corroborate the S/R relationships of Atkinson.
In addition, more experimental kOH data are needed for the 20
chemicals having a percent error greater than +100 to determine
why the percent error was so high.
     A detailed discussion is given in Section III.E. on all the
estimated kOH data including a summary of the statistical data
(Table 26).
     Since the S/R relationships of Atkinson are excellent, these
methods have been computerized for use in Sections 4, 5, and 6 of
the Toxic Substances Control Act  (TSCA) by Syracuse Research
Corporation  (called the Atmospheric Oxidation Program or AOP).
Since this report lists the validated kOH data for a large number
                              -xiv-

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of chemicals, these kOH data have been entered into the data base
in the Syracuse Computer Program.
     This report represents the technical support document for
the "First-Tier Screening-Level Test Guideline  796.3900.
Structure/Reactivity Relationships for Estimating the Second-
Order Rate Constant and Half-Life for the Reaction of Hydroxyl
Radicals with Organic Chemicals in the Troposphere."
     Fifty-six illustrative examples are given in Section IV to
show how to use the S/R relationships of Atkinson to estimate
kOH.  In addition, in order to illustrate the use of the S/R
relationships of Atkinson under Section 4 of TSCA, a hypothetical
scenario has been postulated in which Chemical Company X, located
on Cross Lake near Shreveport, LA, manufactures 2 million kg per
year of the chemical 2,3-difluoro-4-[l-methylpropyl]nitrobenzene
(S).  This chemical is used as a solvent to solubilize some of
the disperse dyes which they manufacture for the textile and
carpet industries.  During the manufacture and use of S, vapors
escape into the atmosphere.  Hence, it is important to determine
the fate of this chemical in the troposphere.  Since S can react
with OH radicals, the S/R relationships of Atkinson were used to
estimate kOjj and the half-life [t^^JEl "* tne troposphere.  A
detailed description of these calculations are given in Section
VI of this report.  Since k0H and ^(i/2)E we^e estimated to be
4.07 x 10~12cm3molecule~1s~1 and 2.6 d, respectively, so that OH
radical reaction represents an important mode of transformation
in the troposphere, it is recommended that S 796.3950 [described
                               -xv-

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in the hierarchal test scheme of Leifer (1989)] be carried out
using the relative rate technique in Teflon bags to measure kOH
for S.
                              -xvi-

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I .    introduction
     Numerous chemicals, both natural and anthropogenic, are
emitted to the troposphere from a variety of sources and may be
removed by wet or dry deposition or by three important
transformation processes.  These three transformation processes
are:
     (1)  direct photoreaction which involves the absorption of
          sunlight followed by transformation;

     (2)  indirect photoreaction which involves the reaction of
          a chemical with hydroxyl radicals  (OH) ; and

     (3)  oxidation which involves the reaction of a chemical
          with ozone (03) .

There is another indirect photoreaction process which involves
the reaction of a chemical with nitrate radicals (NO3) during
the night.  However, this transformation process only occurs
for a few types of chemicals  (e.g., olefins, phenols, and
cresols) ; hence, it will not  be considered when determining the
rate of transformation  in the troposphere.
     A quantitative measure of the three important
transformation processes is given by the rate constants
kOH, and kg  .  The rate constant k^g represents the first-order
rate constant for direct photoreaction, while kQjj and k0
represent second-order rate constants for indirect
photoreaction and oxidation with OH and 03, respectively.
                               -1-

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     The first report in a series titled "DETERMINATION OF
RATES OF REACTION IN THE GAS-PHASE IN THE TROPOSPHERE.  THEORY
AND PRACTICE" describes a hierarchal test scheme for
determining the rate constants JcdE/ kOH, and k0  and the half-
lives [t(!/2)E] for each transformation process and the net
half-life in the troposphere {Leifer [USEPA (1989a)]}.  The
second report describes a screening-level test guideline for
determining the maximum rate of direct photoreaction [k
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     In parallel with the research program of SRI, OTS
sponsored work with Heicklen of Penn. State University, through
a Battelle subcontract, to review the literature on gas-phase
transformations in the troposphere [Heicklen (1980)].  A report
was issued after the completion of this project [Heicklen
(1980)].  As a result of this work, Heicklen (1981) published
an S/R method for estimating kOH for hydroxyl radical H-atom
abstraction from C-H bonds from enthalpy data.
     Another parallel extramural research program was initiated
by the Atmospheric Sciences Research Laboratory (ORD)/Research
Triangle Park, NC, with Atkinson and Pitts (1981)  of the
University of California/Riverside, in support of OTS programs.
This research program was extremely productive and more than 23
research papers and several EPA reports were published.  For
the complete details of the accomplishments of this 3-year
cooperative agreement, the reader is referred to the EPA report
by Atkinson et al. (1985).
     With respect to the reaction of OH radicals with organic
chemicals in the gas-phase, Atkinson and his coworkers:
(1) developed a relative rate method for measuring k_u in
                                                    Un
Teflon bags at approximately one atmosphere pressure in air at
298 K [Atkinson et al.  (1981); Atkinson in Pitts et al.
(1982)];  (2) experimentally measured kOH for a large number of
chemicals in the relative rate/Teflon bag method  [Atkinson et
al.  (1985)];  (3) critically analyzed all the rate data (kOH)
published through 1987 and developed and refined S/R
                              -3-

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relationships for estimating kOH [Atkinson (1986, 1986a, 1987,
1987b, 1988, 1988a)].
     Recently, Atkinson (1989) had a monograph "Kinetics and
Mechanisms of the Gas-Phase Reactions of the Hydroxyl Radical
with Organic Compounds" published by the American Chemical
Society which lists all the experimental kOH data as a function
of the temperature.  The book covers the literature through
1988 and in a number of cases, the temperature range covered
was 220-2000 K.  Atkinson critically analyzed all the
experimental kOH data and recommended rate expressions as a
function of the temperature wherever possible.  In addition,
the rate dependence on pressure was included where data was
available.  He also listed the recommended value of kOH for
each chemical at 298 K, the rationale behind each
recommendation, and the estimated uncertainty for each
recommendation.  Recently, a few of the S/R relationships have
been modified [Atkinson (1989a)].
     In addition, the Atmospheric Sciences Research Laboratory
(ORD)/Research Triangle Park, NC, funded work with Cohen at the
Aerophysics Laboratory/Aerospace Corporation/Los Angeles, CA,
and Benson of the University of Southern California/Los
Angeles, CA, to develop methods of calculating kOH strictly
from theory [Cohen  (1985)].  Cohen and Benson (1985, 1985a,
1987) used transition state theory to calculate kOH for
haloalkanes.
     Leifer critically analyzed all the S/R relationships
described above for estimating kOH and found that the S/R
                              -4-

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relationships of Atkinson were by far:  (1) the most accurate
of all the methods; (2) were applicable to a considerably wider
number of classes of organic chemicals; and (3) were applicable
to a considerably larger number of chemicals.   In addition, the
S/R relationships of Atkinson were adopted by OECD and were
published in a "derestricted OECD document" in 1988 to be used
as guidance to those who decide to carry out gas-phase trans-
formation tests [Atkinson (1987b, 1988a) in an OECD Report].
As a result, this report will describe in detail the S/R
relationships of Atkinson and these methods will be used as a
test guideline for estimating kOH under Sections 4 and 5 of the
Toxic Substances Control Act.
II.  Kinetics of the Reaction of a Chemical with Hydroxyl
     Radicals in the Gas-Phase in the Troposphere
II.A.  Rate Laws
     The kinetics of the reaction of a chemical with OH
radicals in the gas phase, at a constant temperature T (the
absolute temperature in the units K), can be treated
mathematically in the following manner:

                           kOH
                  C + OH 	 Products                  (l)

                  -(dC/dt) = kOH C(OH)                     (2)

where kOH is the second-order rate constant in the units
cm3 molecule"1^"1 and C and  (OH) represent the concentration of
the chemical and hydroxyl radicals, respectively.  In gas-phase
                              -5-

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chemistry, the OH radical and chemical concentrations are
usually expressed in the units molecules cm""3.
     Since a chemical is usually present in the troposphere at
a very low concentration at a given time t and a steady-state
concentration of OH radicals is produced by sunlight, the
hydroxyl radical concentration can be treated as a constant so
that equation 2 becomes a pseudo first-order equation

                       -(dC/dt) - kC                    .   (3)

where

                       k = kOH(OH)                         (4)

The pseudo first-order rate constant k is in the units
reciprocal time, usually s"1.  Integrating equation 3 under the
boundary conditions (t = 0, C0) and (t, Ct)  yields

                       ln(C0/Ct) = kt                      (5)

     The half-life t^^JE ^n tne troposphere is defined as the
time for the chemical concentration to reach one-half its
initial concentration.  Therefore, under the boundary condition
tct " G0/2' t = t(l/2)]' equation 5 yields

                t(l/2)E = ln 2/k = 0.693/k                 (6)
and substituting equation 4 in equation 6 yields

                        " 0.693/kQH(OH)                    (7)
                              -6-

-------
Thus, with the value of kOH, either measured in the laboratory
or estimated by S/R relationships, and the average OH
concentration in the troposphere, the half-life of a chemical
in the gas-phase in the troposphere can be estimated using
equation 7.

II.B.  Effect of Temperature on Rate

     The effect of temperature on the rate constant KOH can be
expressed mathematically in several ways.  A widely used
empirical equation was developed by Arrhenius  (1887) in the
following way.  Arrhenius indicated that the variation of a
rate constant with temperature can be represented by an
equation similar to one used for equilibrium constants, namely

               d[ln k{T}]/dt = AE*/RT2                    (8)

where k{T} is the specific rate constant for a given reaction,
T  is the absolute temperature in the units K, R is the gas
constant which is equal to 1.987 x 10"3 kcal/K/mol or 8.314 x
10~3 kJ/K/mol, and AE* represents the energy of activation for
the reaction in kcal/mol or kJ/mol.  Replacing AE* with E and
integrating equation 8, assuming that E is independent of the
temperature, yields

                In k{T} = In A' - E/RT           x     ..    (9)
                   k{T} = A'exp(-E/RT)                    (,10)
                               -7-

-------
where A' is a constant of integration and is called a frequency
factor, or a preexponential factor.  Equation 10 is usually
valid over a limited temperature range.
     For a number of reactions, A' is not a constant but is a
function of the temperature.  Therefore, a more accurate
empirical equation is
                k{T} = ATnexp(-E/RT)                     (11)

where A and n are constants.  Equation 11 has been used by
Kassel (1932) as an empirical relationship to analyze
experimental kinetic data.  Equation 11 has theoretical
justification, the exponent n having a specific value depending
upon the theory used and the nature of the reaction [Frost and
Pearson (1961); Finlayson-Pitts and Pitts (1986)].
     Collision theory has been used to derive an equation
describing how the rate constant k can vary with temperature
[Frost and Pearson (1961); Finlayson-Pitts and Pitts (1986)].
Collision theory is based on the concept that molecules can be
represented by hard spheres and reaction takes place as a
result of collisions between these spheres.  From this theory,
it can be readily shown that equation 11 is applicable with the
exponent n equal to 1/2 [Frost and Pearson (1961); Benson
(1960); Finlayson-Pitts and Pitts  (1986)].
     Transition state theory has also been used to describe the
kinetics of chemical reactions.  In this theory, the reaction
between two molecules A and B proceeds via the formation of an
activated complex [A--B]$ which then falls apart to form
                              -8-

-------
products.  Using thermodynamics in this theory, it can be

readily shown that a form of equation 11 is applicable with  n

equal to 1 [Finlayson-Pitts and Pitts (1986)].  Using quantum

mechanics in this theory, it can also be shown that a form of

equation 11 is applicable with n also equal to 1  [Eyring  (1935)]


III.  Structure/Reactivity Relationships for Estimating the
      Second-Order Rate Constant (kQH) for the Reaction of
      Hydroxyl Radicals with Organic Chemicals in the Gas-Phase

     Atkinson (1986, 1986a, 1987, 1987b, 1988, 1988a)

critically analyzed the hydroxyl radical rate data  (kOH)  for a

large number of organic chemicals and developed a number  of  S/R

relationships based solely on the molecular structure of  these

chemicals.  In developing these S/R relationships, he assumed

that a number of OH radical reaction pathways exist and the

various OH radical reaction pathways could be separated and

treated individually.  Therefore, he calculated rate constants

for each of these reaction pathways.  The reaction pathways  and

rate constants for each of these pathways were:
    k(l) = k
 H-atom abstraction from acyclic
 saturated,  cyclic saturated,  and
 unsaturated C-H groups  by OH  radicals.
(12)
    k(2) = k  [H-atom  abstraction  from 0-H  groups']         (13)
              [by
    OH radicals                   J

                             ;]
    k(3) = k  [OH radical  addition to  >C=C<,~]              (14)
               >C=C-C=C<,  -CsC-,  and >C=C=C<[
              [.groups
    k(4) = k  [OH radical  interaction with  -SH,]           (15)
              L-s-,
      and -S-S- groups

     idical interact]
L>NH,  and >N- groups
    k(5) = k  [OH  radical  interaction with  -NH2,~]          (16)
                               -9-

-------
    k(6) = k [OH radical interaction with]                (17)
             [phosphorus groups          J
    k(7) = k [OH radical addition to aromatic rings]      (18)
    k(8) = k
OH radical addition to fused ring
polyaromatic compounds (i.e.,
jpolyaromatic hydrocarbons)
(19)
Atkinson postulated that the overall OH radical rate constant
k-.., is equal to the sum of the rate constants for each of these
 On
reaction pathways.  Therefore, the OH radical rate constant  is
given by the equation
                                  8
                           KOH = E
                                i = 1
and the individual rate constants [k(l), k(2),  	, k(8)] and
kOH are all in the units cm3 molecule""1 s"1.  In a few cases,
the estimation of the rate constants are applicable  in the
temperature range 220-1,000 K or 250-500 K; all the  estimations
of the rate constants are applicable at T = 298 K.
Structure/reactivity relationships will be described for each
of these reaction pathways in detail in the following sections.
For convenience, a mathematical synopsis of the S/R
relationships is given in Section VII.

III.A.  H-Atom Abstraction from C-H and 0-H Groups and the
        Estimation of kOH

III.A.I.  Formulation of the Structure/Reactivity Relationships
     Under an OTS extramural contract, Hendry and Kenley
(1979), of SRI International, developed S/R relationships  for

                              -10-

-------
estimating the second-order rate constant kOH for tne reaction
of hydroxyl radicals with organic chemicals in the gas-phase.
Based on a detailed analysis of the available kOH data for a
number of organic chemicals, these researchers postulated that
for H-atom abstraction from C-H groups, there is an intrinsic
rate constant for each C-H reaction center.  These intrinsic
reactivity rate constants are modified by various substituents
at the reaction center ( a position) and adjacent to the
reaction center ( j8 position) .  The total rate constant kOH fr
H-atom abstraction from C-H groups is equal to the sum of the
rate constants for each reactive hydrogen.  Following similar
procedures, they developed S/R relationships for the addition
of OH radicals to olefinic groups and aromatic groups.  The
total rate constant for an organic chemical (kOH) is the sum of
the individual rate constants for H-atom abstraction from C-H
groups, addition to olefinic groups, and addition to aromatic
rings, where appropriate.
     Atkinson (1986, 1986a, 1987, 1987b, 1988, 1988a), in
support of EAB programs, elaborated on and expanded the S/R
relationships of Hendry and Kenley.  Atkinson's S/R
relationships were also based on the premise that CH3-, -CH2-/
and >CH- group rate constants were also dependent on the
identity of the a and 0 substituents.  For the n-alkanes, which
represents the simplest case, Atkinson observed that the -CH2-
group rate constant at approximately 298 K was dependent on the
neighboring groups, increasing from a -CH2- bonded to two CH3-
groups  (CH3-CH2-CH3) through a -CH2- group bonded to one -CH2-
                              -11-

-------
group and one CH3- group (CH3-CH2-CH2-)/ to a -CH2- group
bonded to two -CH2- groups (-CH2-CH2-CH2-).
     For a number of classes of organic chemicals  (e.g., the
alkanes, haloalkanes, aldehydes, ketones, esters, nitriles, and
nitrates, etc.), Atkinson formulated the generalized S/R
relationships for H-atom abstraction from CH3-, -CH2-, and >CH-
groups at 298 K by defining the following mathematical
relationships:

                    k(CH3-X) = k F(X)                   (21)

                  k(X-CH2-Y) - k F(X) F(Y)              (22)

                        /Y
                  k(X-CH   ) = kg F(X) F(Y) F(Z)         (23)
                        \Z
where:  k, k- and k? represent the group rate constants for
primary OH groups (CH3-), secondary C-H groups (-CH2-), and
tertiary C-H groups  (>CH-), respectively, for a standard
substituent X; F(X), F(Y), and F(Z) represent factors for the
substituents X, Y, and Z, respectively; and the standard
substituent, for practical reasons, was postulated as X = Y = Z
= CH3-, and F(CH3-) = 1.00.
     In addition, for organic compounds containing hydroxyl
groups  (-OH), H-atom abstraction from this group was included
as a reaction pathway and this group rate constant was
designated as k(-OH).  It should be noted that the group rate
constant for H-atom abstraction from the OH functional group is
                              -12-

-------
written as k(-OH) to distinguish it from the total OH rate
constant koH*
     Atkinson then used the following approach for H-atom
abstraction from a number of classes of organic compounds:
e.g., acyclic and cyclic alkanes, haloalkanes, aldehydes,
ketones, alcohols, etc.  Most of the available kOH data were
for compounds containing single functional groups, with very
little data available for compounds containing difunctional and
polyfunctional groups.  Furthermore, the alkanes  (acyclic and
cyclic) had the largest number of chemicals with kOn data.  As
a result, Atkinson analyzed the kinetic data sequentially in
the following order:  alkanes (acyclic), alkanes  (cyclic);
haloalkanes; carbonyl compounds such as aldehydes, ketones,
ot-dicarbonyls, acid chlorides, and esters; alcohols, glycols,
and ethers; nitrates; and nitriles.  Using the available kOH
data for alkanes, he formulated S/R relationships for this
class of compounds.  Then, using the S/R relationships for
alkanes and the kOH data for haloalkanes, he developed S/R
relationships for the haloalkanes.  This process was repeated
sequentially for the other classes of compounds listed above.
For the purposes of validation, Atkinson compared the
experimental values of k0jj with the estimated values.  This
validation procedure was also used for the other classes of
chemicals discussed in this report.
     First, let us consider the acyclic alkanes with a general
structure RCH2CH(CH3)2  This molecule contains primary,
secondary, and tertiary carbon-hydrogen groups  (CH3-, -CH2-,

                              -13-

-------
and >CH-, respectively) and R is an alkyl group.  The hydroxyl
radical reacts with each of these C-H groups by abstracting a
hydrogen as follows:

                                    CH3
                             RCH2--CH3 + HOH          (24a)
3 RCH2CH(CH3)2 + 3(OH)
                                     13
                           	 RCH-CH-CH3 + HOH          (24b)

                                   9H3
                           * RCH2-CH-CH2+ HOH          (24c)

The rate of H-atom abstraction from these three groups is in
the order:  tertiary C-H > secondary C-H > primary C-H [i.e.,
>CH- > -CH2-, > CH3-].  For the acyclic alkanes, equation 20
reduces to

         k(la) = k [H-atom abstraction from C-HJ         (25)
                   [bonds in acyclic alkanes   J

     Atkinson made a detailed study of the temperature
dependence of the group rate constants (kp, kg, k) in the
range 220 - 1,000 K.  For this temperature range, the modified
Arrhenius equation (equation 11), with n = 2, in the form

                k{T} - A'T2 exp(-E'/T)                   (26)

was found to be applicable.  In equation 26, the energy  of
activation E' is equal to E/R and the preexponential factor A
is equal to A'.  For the narrower temperature range 250-500 K,
the simple Arrhenius equation (equation 10) was found to be
applicable.
                              -14-

-------
     Equation 26 was used to obtain the group rate constants
*p, *!/ *t (defined by equations 21, 22, and 23) in the
temperature range 220 - 1,000 K.  Making the assumption that
the effects of the substituent X are only on the activation
energy E" and not on the preexponential factor A', then, from
equation 26,  the substituent factor F(X) is given by the
equation
                      F(X) =
exp E(X)/T                 (27)
where E' = E(X) .  To a good approximation, this assumption is
valid since any deviations in the data will be small and within
the uncertainties of the experimental rate data.
     Using the extensive set of kOH data for the acyclic
alkanes, Atkinson (1986, 1986a) carried out a nonlinear, least-
squares fit of the data to the equation

  kOH = k(la)

            F(X) +  J>! F(X) F(Y) +  kg F(X) F(Y) F(Z) (28)
and calculated k2, kg, and kg as a function of the temperature
Using these results in the modified Arrhenius equation 26, he
found that

                kp = 4.47 x 10~18T2exp(-303/T)            (29)

                k2 = 4.32 X 10"18T2exp(233/T)             (30)
                              -15-

-------
                kf = 1.89 x 10~18T2exp(711/T)             (31)






and





     F(-CH2-) - F(>CH-) - F(>C<) = exp(76/T)              (32)
     The first term in equation 28 represents the sum of the



contributions from each primary group (CH3-) in an alkane; the



second term represents the sum of the contributions from each



secondary group (-CH2-) in the alkane; and finally, the third



term represents the sum of the contributions from each tertiary



group ( >CH-) in an alkane.



     Using equations 29 through 32, the group rate constants



kg, kj, kg, and the factors F(X) at 298 K are given by





            kg = 0.144 x 10~12 cm3 molecule'1^"1         (33)





            kg = 0.838 x 10~12 cm3 molecule~1s">1         (34)





            kg - 1.83 x 10~12 cm3 molecule' 1s~1          (35)





            F(-CH2-) = F(>CH-) = F(>C<) - 1.29           (36)





and by definition





                       F(CH3-) = 1.00                    (37)





The group rate constants kg, k, and k at 298 K, the



preexponential factors A', and the energies of activation E'[=



E(X)] are all summarized in Table l.  For the substituent
                              -16-

-------
Table 1.  Group Rate Constants k and k at 298 K and the
          Parameters A' and E' [ = E(X)] in Equation 26

Group Rate       1012k                1018A'         E(X) = E'
 Constant    (cm3 molecule"3^"1)   (cm3molecule~1s~1)     (K)
k
KP
k
Ks
kt
k(-OH)
k(l,UNS CH)a
k(-NH2)
k(>NH)
k(>N-)
k(-SH)
k(-s-)
k(-S-S-)
k(>N-NO)
k(>N-N02)
k[P(0)]
k(PCl)c
k[P(S)]
0.144
0.838
1.83
0.036
0
20
60
60
31d
2.0b
200
0
0
0
0
55
4.47 303
4.32 -233
1.89 -711
1.89 460
- -
-
-
- -
-
- -
-
- -
-
- -
-
-
a k(l, UNS CH) represents the group rate constant for
  abstraction of a hydrogen from an unsaturated carbon-carbon
  functional group.  Even at elevated temperatures up to 500 K,
  k(l,UNS CH) is approximately zero [Atkinson  (1987)].

b Applicable at 298 K and at a total pressure  of 1 atmosphere
  in air  (and thus in the presence of oxygen).  In the absence
  of oxygen, k(-S-)  = 0.

c Applicable to PCI in the compounds  (RiO)2P(S)Cl, where R^ is
  an alkyl group.

^ Applicable only to aliphatic group; connection to aromatic
  rings is not included based on the experimental rate constant
  of thiophenol [Meylan  (1990)].
                              -17-

-------
groups X, the data for F(X) at 298 K, and E(X)  (where avail-



able) are listed in Table 2.



     To illustrate Atkinson's method of calculating k... at
                                                     Urt


298 K, consider the acyclic alkane





                           CH3



                           i

                           H
                       CH3-C-CH2-CH2-CH3                  (38)
Using equation 28, and starting at the first carbon at the left



and then proceeding from carbon to carbon to the right, one



obtains





kOH - k(la)





     - k, F(>CH-) + kg F(CH3-) F(CH3-) F(-CH2-)





         + kg F(>CH-) + k F(>CH-) F(-CH2-)               (39)





             + k| F(-CH2-) F(CH3-) + k F(-CH2-)





     Atkinson [1986, 1986a, 1987, 1987b, 1988, 1988a] indicated



that for strained cyclic alkanes, energies greater than 5



kcal/mol lead to a decrease in H-atom abstraction rate



constants.  Therefore, the effects of ring strain must be taken



into account when estimating kOH for cyclic alkanes.  Since the



decrease in the rate constant kOH is related exponentially to



the ring strain energy, the decrease in kOH will be evident in



the activation energy term F(X) = exp[E(X)/T], equation 27, and



not in the preexponential factor A' in equation 26.  Based on a



detailed analysis of the kOH data for the strained cyclic rings



cyclopropane, cyclobutane, and cyclopentane, and unstrained



                              -18-

-------
Table 2.  Substituent Factors F(X) at 298 K and E(X) in
          Equation 26  for Various Substituents X
Substituent Grouo X
CH3-
-CH2-, >CH-, >C<
F-
Cl-
Br-
-CH2C1, -CHC12, -CH2Br, >CHCla
C13C-
FCH2-
F2CH-
F2C1C-
F3C-
=0 or (0)
-C(0)C1
-CH(0), -C(0)-
-CH2C(0)- , >CH-C(0)- , C-C(0)-
2nd-CH2C(0)-, 2M>CHC(0)-/ 2nd^CC(0)-
C6H5-
>C=C< , -CsC-
-OH
-0-
2M -o-
-CH2-0-
*C-0-
FfX)
1.00
1.29
0.099
0.38
0.30
0.57
0.090
0.85
0.10
0.025
0.075
8.8
0.50
0.76
4.4
1.0
1.0
1.0
3.4
6.1
1.0
4.5
4.5*
E(X)
m
0
76
-689
-288
-359
-168
-718
-48
-686
-1099
-771
648
-207
-82
442
0
0
0
365
539
	
	
___
                              -19-

-------
Table 2.  Substituent Factors F(X) at 298 K and E(X) in
          Equation 26 for Various Substituents X  (Continued)

                                                           E(X)
	Substituent Group X	      Fm          m
                 -OC(0)R                       1.5          121

                -OC(0)CF3                      0.36

                -C(0)-0-R                      0            	

          -SH , -S- , -S-S-                    9.0          	

          -NH2/ >NH-, >N-                     10            	

              >N-NO , >N-N02                  10            	

              >NOH, -NHOH                     10d           	
-CH2-ONO2/ >CH-ON02, C-ON02
-ON02
-CN
-CH2CN
-0-P< , -S-P<
F(3)
F(4)
F(5)
F(6)
F(7), F(8), etc.
0.30
0.10
0.14
0.50
20
0.017
0.22
0.80
1.00
1.0
a Estimated bv A. Leifer using the experimental value of :
0.96 x 1O~" cm^molecule'^s"1 for 2,3-dichlorobutane at
  
-686
-586
-207
	
-1214
-451
-66
0
0
298 K
   [from Mill et al.  (1982)].

b  Given the same value as for -CH2-O-  [Meylan  (1990)].

c  Estimated by Leifer using the experimental value of
   0.052 x  10~^ cm^molecule~1s~1  from  the experimental data  of
   Wallington et al.  (1988) of CF3C(0)OCH3.

^  Estimated by Leifer based on the experimental data of
   diethy1-N-hydroxylamine.
                              -20-

-------
rings such as cylohexane, etc., Atkinson indicated that

       F(3) = 0.017; F(4) = 0.22; F(5) = 0.80             (40)

       F(6) = 1.00; F(7) = F(8) = 1.0                     (41)

All these substituent factors F(X) for cyclic alkanes at  298 K
are listed in Table 2.
     From equations 20 and 12 for unsubstituted cyclic alkanes

                  kOH = k(lc)                             (42)

and modifying equation 28 for cyclic alkanes, one obtains
kOH = k(lc)

    = |E kg F(X)F(Y) + E kg F(X)F(Y)F(Z)j F(i)             (43)

where F(i) is the ring strain factor corresponding to a ring
with i carbons.
     As an example, consider cyclopropane
                   H2C CH2                               (44)

Using equation 43  in the same manner as described previously,
and the ring strain factor F(3)  for the cyclopropane ring,  one
obtains
            kOH = k(lc) = [3k F2(-CH2-)
F(3)           (45)
with the short-hand notation
                              -21-

-------
               F2(-CH2-) = F(-CH2-) F(-CH2-)              (46)

     When calculating JcOH [Jc(lc)] for alkyl substituted cyclo-
alkanes, the ring substituents are unaffected by ring strain
while the various C-H groups within the ring are affected by
strain.  As a result, equation 43 is valid for the cyclic
alkane while equation 28 is valid for the acyclic component.
As an example, consider the compound isopropylcyclopropane

                      CH-CH(CH3)2
                                                          (47)
                  CH2	CH2

The ring C-H groups must be separated from the substituted
acyclic C-H components.  Thus, from equations 20, 28, and 43,
one obtains

kOH - k(lc) + k(la)

    = jkt F2(-CH2-) F(>CH-) + 2k;F(-CH2-) F(>CH-)j F(3)
                                                          (48)
         + kg F2(CH3-) F(>CH-) + 2kpF(>CH-)

     Atkinson, in Atkinson and Aschmann  (1988), measured  k0n
for this compound at 298 K and found that kOn [Experimental]
was equal to 2.83 x 10~12cm3 molecule"3^"1.  Atkinson  (1989)
revised this value slightly to 2.84 x 10"12cm3 molecule~1s"1.
The estimation of JCQH for this compound  is given as  an
illustrative example  [See Section IV.A.3.].  Using equation 48,
    [Estimated] = 2.85 x 10~12cm3 molecule'^-s'1.  Clearly,  the
                              -22-

-------
estimated XQH value is in excellent agreement with the
experimental value indicating that the ring strain has no
effect on the reactivity of the isopropyl substituent group.
     For polycyclic rings, the ring strain factors are
multiplicative.  For example, for bicyclo[2.2.1]heptane

                     CH,
H-
           H2C
                           *CT2
                                                        '  (49)
      k
        2k? F3(-CH2-) + kg F2(>CH-)

         + 4k F(>CH-) F(-CH2-)j F2(5) F(6)               (50)

Again, it should be noted that  for alkyl substituted polycyclic
compounds, the ring correction  factor F(i) is only applied to
the -CH2- and >CH- groups within the ring and not to
substituted alkyl groups.
     As an illustration, consider the compound bicyclo[3.3.0]
octane:  th experimental value of kO}] is 11.0 x 10~12
cm3 molecule^s""1  [Table 3.B./Atkinson, Aschmann, Carter
(1983a)]; the estimated value of kOH is 10.4 x 10~12cm3
molecule~1s~1  (see illustrative example IV.A.2); again, in this
case, the experimental value is in excellent agreement with  th
                              -23-

-------
estimated value and clearly confirms the S/R relationships for
strained polycyclic alkanes.  [See also the data for other
bicyclic and tricydie alkanes in Table 3.B.]
     Furthermore, since strain energies for rings containing
heteroatoms O, S, N are similar to the corresponding
cycloalkanes, the ring factors F(3), F(4), and F(5) are also
applicable to strained heterocyclic rings such as cycloethers,
cycloamines, and cyclosulfides.
     The formulation of S/R relationships for classes of
compounds containing hydroxyl groups (-OH) will be discussed in
Section III.A.2.d. Alcohols, Glycols, and Ethers.
III.A.2.  Estimation of kOH for Several Classes of Organic
          Chemicals at 298 K and a Comparison of These Results
          with the Experimental Data
III.A.2.a.  Alkanes
III.A.2.a.i. Acyclic Alkanes
     Table 3.A. summarizes the pertinent !CQH data at 298 K for
the reaction of OH radicals with acyclic alkanes as obtained
from the literature.  The first column lists the name of each
acyclic alkane.  The second column, labeled Experimental/(a),
lists the experimental values of kOH as obtained from Atkinson
(1986).  These kQH data represented the best available values
at that time.  The underlined values of kOH in this column
(i.e., those values above the dashed line in Table 3.A.) were
used by Atkinson  (1986, 1986a) to derive the S/R relationships
for acyclic alkanes.  In a monograph published recently,
Atkinson  (1989) critically reviewed all the available kOH data
                              -24-

-------
Table 3.A.  Comparison of Experimental and Estimated Values of k0H
            Acyclic Alkanes at 298 K and the Percent Error [Underlined
            Values of Rate Constants Were Used by Atkinson (1986, I986a)
            to Derive the Group Rate Constants and Substituent Factors
            Listed in Tables 1 and 2, Respectively, for the Acyclic
            Alkanes.]
Chemical
Ethane
Propane
n- Butane
2 -Methy Ipropane
n-Pentane
2-Methylbutane
2 , 2 -Dime thy Ipropane
n-Hexane
2 -Methy Ipent ane
3 -Methy Ipentane
2 , 2-Dimethylbutane
n-Heptane
2 , 4 -Dimethy Ipentane
2,2, 3-Trimethylbutane
n-Octane
2,2, 4-Trimethylpentane
2,2,3, 3-Tetramethylbutane
n-Nonane
1012 kOH (cm3molecule~1s~1)
Experin
(a)
0.274
1.18
3r53
2.37
4_^0
3.9
0.852
5.58
5_^
1^6.
2^1
lil
5^1
4^
8.72
3.66
1.06
10.0
lent a 1
(b)
0.268*
1.15*
2.54*
2.34*
3.94*
3.9*
0.849*
5.61*
5.6*
5.7*
2.32*
7.15*
5.16
4.23*
8.68*
3.68*
1.08*
10.2
Estimated
0.288
1.21
2.53
2.39
3.92
4.00
0.743
5.32
5.39
5.77
1.83
6.71
6.85
3.30
8.11
4.68
1.11
9.50
Percent
Error*-
+7
+ 5
0
+2
-1
+3
-12
-5
-4
-t-1
-21
-6
+ 33
-22
-7
*27
 3

                                -25-

-------
Table 3.A.  Continued
Chemical
n-Decane
H-Undecane
n-Dodecane
n-Tridecane
2 , 3-Dimethylbutane
2 , 2-Dimethylpentane
2 , 2-Dimethylhexane
2,3, 4-Trimethylpentane
2 -Methy loctane
4 -Methy 1 octane
2,3, 5-Trimethylhexane
n-Tetradecane
H-Pentadecane
n-Hexadecane
1012 kOH (cm3molecule"1s~1)
Exoerimental
(a)
11,3
13.3
13.9
15.5
6.2









(b)
11.6*
13.2*
14.2*
16*
6.2*
3.37
4.83
6.97d
10. lc
9.72
7.78C
19. 2e
22. 2e
24. 9e
Estimated
10.9
12.3
13.7
15.0
5.46
3.22
4.61
8.70
9.58
9.95
10.1
16.5
17.9
19.3
Percent
Errorf
-6
-7
-4
-6
-12
-4
-5
+25
-5
+ 2
+30
-14
-19
-22
a Experimental data from Atkinson  (1986).
b Experimental data from Atkinson  (1989) and the literature.
c Experimental data is from Behnke et al.  (1988).
" Experimental data is from Harris and Kerr (1988).
3 Experimental data is from Nolting et al. (1988).
f Based on the experimental data given in the third column,
  Experimental/(b).
* Recommended value by Atkinson  (1989) with the rationale for the
  recommendation,  and the uncertainty for the recommendation.
                                -26-

-------
published in the literature up to 1988 and listed the recommended
values at 298 K, the rationale behind each recommendation, and
the uncertainty for each recommendation.  These values have an
asterisk after the value and are listed in the third column
labeled Experimental/(b).  The values of kOH without an asterisk
were not recommended by Atkinson either because of the limited
temperature dependence data or the limited data from a single
source.  These data, however, represent the best available kOH
values at 298 K up to 1989.  The fourth column lists the
estimated values of kOH using the S/R relationships of Atkinson;
and finally, the fifth and last  column lists the percent error
of the estimated value of kOH relative to the experimental values
listed in the column labeled Experimental/(b).
     The underlined values of k0n in tne second column, repre-
senting the first 19 alkanes listed above the dashed line, were
used by Atkinson (1986, 1986a) to derive the group rate constants
and substituent factors for the alkanes.  These group rate
constants and substituent factors are given in equations 33, 34,
35, 36, and 37, respectively, and are listed in Tables 1 and 2.
     One of the best ways of testing Atkinson's S/R relationships
for the acyclic alkanes is to apply them to the calculation of
kOH for compounds which were not used to derive the group rate
constants and substituent factors.  This was carried out for the
13 acyclic alkanes listed below the dashed line in Table 3.A.
Thus, using equation 28, for H-atom abstraction from C-H bonds in
these alkanes, kOH  [= k(la)] was estimated at 298 K.  The average
percent error for these 13 compounds, based on the kOH data in
                              -27-

-------
the column Experimental/(b),  was +19(1) to -10.  These results
ranged from excellent to superb(2) ,  thereby confirming the S/R
relationships of Atkinson for the acyclic alkanes.
     The average percent error for all 32 acyclic alkanes listed
in Table 3.A. ranged from +12 to -9.  These results, therefore,
ranged from excellent to superb.

III.A.2.a.ii.  Cyclic Alkanes
     Table 3.B. lists the pertinent kOH data at 298 K for 18
cyclic alkanes as obtained from the literature.  This table is in
exactly the same format as Table 3.A. as described in the first
paragraph of Section III.A.2.a.i.
     The underlined values of kOH in the second column,
representing the first 14 cycloalkanes above the dashed line,
were used by Atkinson (1986,  1986a), along with the knowledge of
the strain energies in these rings,  to derive the substituent
factors F(3), F(4), F(5), F(6), etc.  These substituent factors
are given by equations 40 and 41 and are listed in Table 2.
     To test the validity of the S/R relationships of Atkinson,
the estimated values of kOH were compared to the experimental
values of those compounds not used to derive the substituent
1 The average positive error was calculated based on the total
  number of chemicals with a positive error plus those with a
  zero error.
2 The descriptive ratings for this class of chemicals and those
  in later sections are based on the following scale:  superb
  <10%; excellent >10% and <20%; very good >20% and <35%; good
  >35% and <55%; relatively poor >55% and <100%.
                              -28-

-------
Table 3.B.  Comparison of Experimental and Estimated Values of kOH  for
            Cyclic Alkanes at 298 K and the Percent Error  [Underlined
            Values of Rate Constants Were Used by Atkinson  (1986, I986a)
            to Derive the Substituerit Constants for the Cycloalkanes
            Listed in Table 2.]
chemical
Cyclopropane
Cyclobutane
Cyclopentane
Cyclohexane
Cy c lohept ane
B icy c lo [2.2.1] heptane
Bicyclo [2.2.2] octane
Bicyclo [ 3 . 3 . 0 ] octane
cis.-Bicyclo [4.3.0] nonane
trans-Bicvclo [4.3.0] nonane
cis-Bicvclo [4.4.0] decane
trans -Bicyclo [4.4.0] decane
Tr icyclo [ 5 . 2 . 1 . O2  6 ] decane
Tricyclo [ 3 . 3 . 1 . I3  7 ] decane
Me thy 1 cy c 1 ohexane
i-Propylcyclopropane
Cyclooctane
1,1, 3-Trimethylcyclohexane
1012 k0jj (cm^molecule'^s"1)
Experimental
(a)
0.07
5*2.
7.38
13.1
5.42
14.5
10.9
17.0
17.4
19.6
20.2
11.2
22.7
10.3
	
__..
(b)
0.071
1.2h
5.16*
7.49*
12. 5d
5.49e
14. 7e
11.0
17. 2e
17. 6e
19. 9e
20. 4e
11. 3e
22. 6f
10. 41
2.84J
13. 7k
8.73k
Estimated
0.0711
1.23
5.58
8.37
9.77
9.49
16.2
10.4
14.1
14.1
19.0
19.0
12.3
24.1
10.2
2.85
11.2
9.18
Percent
Error?
+1
+3
+8
+ 12
-22
+73
+ 10
-5
-18
-20
-5
-7
+9
+9
-2
0
-18
+5
a Experimental Data from Atkinson (1986).
b Experimental Data from Atkinson (1989).
C At7Av>arra walna fvmrn t-he ovnoyi mont-a 1 Ha-ha nf 7o^-y!r'H MQQn\ ariH .Toller
d

e
  et al.  (1985) .
  Average value of the  experimental data  from Jolly  et  al.  (1985)  and
  Behnke et al.  (1988)  as  reported by Atkinson.
  Experimental  data  from Atkinson, Aschmann, and  Carter (1983a) .
  Average value from the experimental data of Atkinson,  Aschmann,  and
  Carter  (1983a)  and Behnke  et  al.  (1988).
  Based on the  experimental  data  given  in the third  column,
  Experimental/ (b) .
  Experimental  value from  Gorse and Volman  (1974).
  Experimental  value from  Atkinson et al.  (1984) .
  Experimental  value from  Atkinson and  Aschmann  (1988) .
  Experimental  value from  Behnke  et al.  (1988) as reported  in  Atkinson
   (1989).
  Recommended value  by  Atkinson (1989)  with  the rationale for  the
  recommendation,  and the  uncertainty for the recommendation.
                                -29-

-------
factors for the cyclic alkanes.  Therefore, for the four
compounds listed below the dashed line, kOH was estimated using
equations 28 and 43, where appropriate; and these results are
listed in the fourth column of Table 3.B.  The average percent
error, based on the experimental kOH values listed in the third
column, ranged from +3 to -10 and these results are superb,
confirming the S/R relationships for cyclic and acyclic
alkanes.
     The average percent error for all 18 cyclic compounds
ranged from +13 to -12 and these results are excellent.

III.A.2.a.iii.  All Alkanes (Acyclic and Cyclic)
     Of the 50 alkanes analyzed, 17 compounds were not used to
derive the group rate constants and substituent factors.  The
average error for these 17 compounds ranged from +12 to -10
which ranged from excellent to superb, thereby confirming the
S/R relationships of Atkinson for the alkanes.
     For all 50 alkanes (acyclic and cyclic) listed in Tables
3.A. and 3.B., the average percent error ranged from +12 to
-10.  These results, therefore, ranged from excellent to
superb.
III.A.2.b.  Haloalkanes
     Table 4 lists the pertinent kOH data at 298 K for 32
haloalkanes as obtained from the literature.  This table is in
exactly the same format as Table 3.A. and the column headings
are exactly the same as those described in the first paragraph
of Section III.A.2.a.i.  It should be noted that the
                              -30-

-------
Table 4.  Comparison of Experimental and Estimated Values of kOH for
          Haloalkanes at 298 K and the Percent Error [Underlined
          Values of Rate Constants Were Used by Atkinson (1986, 1986a)
          to Derive the Substituent Factors Listed in Table 2 for the
          Haloalkanes]
Chemical
Fluor ome thane
Chloromethane
Bromomethane
Dif luor ome thane
F luor och lor ome thane
Dichloromethane
Tr i f luor ome thane
Dif luorochloromethane
Fluorodichloromethane
Chloroethane
1, 1-Dif luoroethane
1, 1-Dif luoro-1-chloroethane
1,1, 1-Trichloroethane
1,1,1, 2 -Tetraf luoroethane
l-Chloro-2 , 2 , 2 -tr if luoroethane
2 , 3-Dichlorobutane
Trichlorometharie
F luoroethane
1 , 2 -Dif luoroethane
1 , 1-Dichloroethane
1 , 2-Dibromoethane
1,1, 1-Tr if luoroethane
1,1, 2 -Tr if luoroethane
1,1, 2-Trichloroethane
1 , 2-Dichloro-2 , 2-dif luoroethane
1014 kOH (cm3molecule~1s~1)
Experimental
(a)
1.68
4.36
3.93
1.09
4.41
14.2
0.020
0.468
3.03
40.0
3.4
0.358
1.19
0.854
1.62
96d'h
10.3
23.0
11
26
25
-0.20
1.8
32.8
<1.9
(b)
1.68*
4.36*
4.02*
1.09*
4.41*
14.2*
0.024
0.468*
3.03*
39*
3.4*
0.358*
1.19*
0.854*
1.62*

10.3*
23. 2e
11. 2f
26.09
25.09
0.171f
1.83f
32.43
2.61*
Estimated
1.43
5.47
4.32
0.821
3.15" .
12.1
	
0.682
2.62
40.0
3.23
0.360
1.30
0.622
2.39
95.7
10.0
20.5
14.1
34.6
28.7
1.08
2.35
33.3
0.796
Percent
Error1
-15
+25
+7
-25
-29
-15
	
+46
-14
+3
-5
+1
+9
-27
+48
0
-3
-12
+26
+33
+15
+440
+23
+2
-70
                                -31-

-------
Table 4.  Continued
Chemical
Pentaf luoroethane
1-Chloro-l ,2,2, 2 -tetraf luoro-
ethane
1 , l-Dichloro-2 , 2 , 2-trif luoro-
ethane
2 -Chlorobutane
1, 2-Dichloroethane
1,1,2, 2 -Tetraf luoroethane
1 , 2-Dibromo-3-chloropropane
1014 kOH (cm3molecule~1s~1)
Experiment a 1
(a)
0.25
1.02
3.35
230d
	
(b)
0.249f
1.02*
3.35*
	
22.09
0.67*
43. 51
Estimated
0.135
0.516
1.98
164
36.3
0.359
50.3
Percent
Error1
-46
-49
-41
-29
+65
-46
+16
a Experimental data from Atkinson (1986).
b Experimental data from Atkinson (1989).
C cinr>a +h ovneiri mental rls + s uaCHC1) =0.57 which is listed in Table 2.
  Based on the Experimental data given in the third  column,
  Experimental/ (b) .
  Extrapolated from the experimental data of Jeong and Kaufman  (1979)
  and Jeong et al. (1984) .
  Extrapolated from the experimental data of Clyne and Holt (1979) .
  Experimental data from Tuazon et al. (1986) .
  Recommended value by Atkinson (1989) with the rationale for the
  recommendation and the uncertainty for the recommendation.
                                -32-

-------
experimental JCQH data for trifluoromethane was not included in
the analysis given below.  That is, the data at 298 K was
obtained from the extrapolation of the experimental data at
>387 K and, therefore, must be used with caution at
temperatures <300 K [Atkinson (1989)].
     Using the appropriate group rate constants (k) and
substituent factors F(X) for the alkanes from Tables 1 and 2,
respectively, Atkinson  (1986) carried out a nonlinear least-
squares fit of the underlined experimental kOH data of the
haloalkanes  (i.e., the  14 underlined compounds listed above the
dashed line) to equation 28 and derived the following
substituent factors F(X) for the haloalkanes:

   F(F-) = 0.099; F(Cl-) = 0.38; F(Br-) = 0.30            (51)

   F(C1CH2-) - F(C12CH-) = F(BrCH2-) = 0.57               (52)

   F(C13C-) = 0.090;  F(FCH2-) = 0.85; F(F2CH-) = 0.10     (53)

   F(C1F2C-)  0.025; F(F30) = 0.075                     (54)

The values of these substituent factors [F(X)], along with the
corresponding values  of E(X), are  listed in Table 2.  It should
be noted that the substituent factor F(C13C-) was adjusted
slightly from a value of 0.083  [Atkinson (1986)] to 0.090
[Atkinson  (1987)] to  optimize the  fit of the 298 K rate
constants  (kOH) for CH3CC13 and C13CCHO.
     The rate constants kOH for 2,3-dichlorobutane and
2-chlorobutane were measured by Mill et al.  (1982) at 298 K.
                                                /
Using the measured value of kOH for 2,3-dichlorobutane, Leifer
                              -33-

-------
estimated that the substituent factor F(>CHC1) was equal to
0.57 and this value is listed in Table 2.  Since this compound
was used to derive this substituent factor it is listed above
the dashed line in Table 4.
     Using the group rate constants k for the alkanes from
Table 1 and the appropriate substituent factors F(X) from
Table 2, kOH was estimated using equation 28 for the remaining
16 haloalkanes listed in Table 4 (i.e., those compounds listed
below the dashed line which were not used to derive the substi-
tuent constants for the haloalkanes) along with the percent
error.  Only 1,1,1-trifluoroethane had an error greater than
+100 percent (+440) and was dropped in subsequent analyses.3
Excluding the value for this compound, the average percent
error of the remaining 15 compounds ranged from +26 to -37.
These results ranged from very good to good, confirming the S/R
relationships of Atkinson for the haloalkanes.
     The average percent error for all 30 compounds (which
excluded 1,1,1-trifluoroethane and trifluoromethane) ranged
from +21 to -28 so that these results are very good.

III.A.2.c.  Carbonyl Compounds:  Aldehydes, Ketones,
            o-Dicarbonyls, Acid Chlorides, and Esters
     The experimental values of kOH at 298 K for 52 carbonyl
compounds:  aldehydes (11 compounds); ketones [19 compounds
3 The value of +100 was chosen so that only a minimum number of
  chemicals would be dropped from the total number of chemicals
  used to obtain the average percent error.  See Sections
  III.A.2.b. and III.A.3.; Summary Tables 8, 17, 21, 25 and 26;
  and Section III.E.
                              -34-

-------
(comprised of 16 acyclic and 3 cyclic compounds) ]; ot-dicarbonyls
(3 compounds); acyl chlorides (l compound); and esters  (18
compounds) are listed in Table 5 as obtained from the
literature.  Using the appropriate group rate constants and
substituent factors from Tables 1 and 2, Atkinson carried out a
nonlinear least-squares fit of the experimental KOH data of 13
of the aldehydes and ketones (i.e., the underlined values of
k0H above the dashed lines in Table 5.A. and B.) to equation 28
and derived the following substituent factors [Atkinson
(1986)]:

          F(=0) = 8.8; F[-CH(0)] = F[-C(0)-] = 0.76       (55)

        F[-CH2C(0)-] = F[>CHC(0)-] = F^CC(O)-] = 4.4     (56)

     Atkinson  (1989a) reevaluated the k0n data for the
aldehydes and ketones and indicated that for compounds
containing a second aIkyl-(CO)-group, the substituent factor is

              F [ 2^ R-C(O)- ]   = 1.00                    (57)

     Similarly, for the esters, Atkinson (1987) carried out a
nonlinear least-squares fit of the experimental data of 5 of
these compounds (i.e., those underlined values of kOH above the
dashed  line in Table 5.F.) and derived the substituent  factors

            F [ -OC(0)R ]  = 1.5; F [ -C(0)OR ]   = 0         (58)
     Furthermore, Atkinson (1987) estimated the substituent
factor  for the acyl chlorides from the experimental kQjj data of
                              -35-

-------
Table 5.  Comparison of Experimental and Estimated Values of kOH for
          Carbonyl Compounds at 298 K and the Percent Error (Underlie
          Values of k0H Were Used by Atkinson (1986, 1987) to Derive
          Substituent Factors for the Carbonyl Compounds)
Chemical Class/Chemical
A. ALDEHYDES
Formal
Ethanal
Propanal
Trichloroacetaldehyde
Butanal
2 -Methy Ipr opana 1
Pentanal
3 -Methy Ibutanal
2 , 2-Dimethylpropanal
Pentane-1 , 5-dial
Hydr oxy ethana 1
(Glycolaldehyde)
B. ACYCLIC KETONES
Propanone
2 -Butanone
2-Pentanone
3-Pentanone
2-Hexanone
3-Hexanone
1012 kOH (cm-^molecule'^-s'1)
Exoerin
(a)

9_L
16.2
19.6
1.95

23
27
27
27
27
	
	

0.23
1^0
4.64
1.82
8.97
6.81

lent a 1
(b)

9.77*
15.8*
19.6*
1.73
23.5*
26.3*
28.5*
27.4*
26.5*
23. 8d
9.9e

0.226*
1.15*
4.9*
2.0*
9.1*
6.90
Estimated

7.37
16.2
22.0
1.45
25.5
23.4
27.6
30.0
22.7
46.9
23.0

0.219
1.38
4.81
2.56
6.96
5.97
Percent
Error"

-25
-1-3
+12
-16
+9
-11
-3 (
+9
-14
+110
+132

-3
+20
-2
+28
-24
-13
                                -36-

-------
Table 5.  Continued
Chemical Class/Chemical
2 , 4-Dimethyl-3-pentanone
4 -Me thy 1-2 -pentanone
2 , 6-Dimethyl-4-heptanone
3 , 3-Dimethyl-2-butanone
2-Heptanone
2-Octanone
2-Nonanone
2-Decanone
2 , 4-Pentanedione
2 , 5-Hexanedione
C. CYCLIC KETONES
Cyclobutanone
Cyclopentanone
Cyclohexanone
D. a-DICARBONYLS
Glyoxal
Methylglyoxal
Biacetyl
E. ACYL CHLORIDES
Acetyl chloride
1012 kOH (cm3molecule~1s"1)
Experimental
(a)
5.31
14.1
27.1

	
	
	
	
	
	

	
	
	

11.2
16.9
0.24

0<068h,i

(b)
5.38
14.1*
27.5*
1.21*
8.67f
11.0*
12. 2f
13. 2f
1.159
7.139

0.879
2.949
6.399

11.4*
17.2*
0.238*

0.068
Estimated
5.31
9.35
18.5
2.01
8.35
9.74
11.1
12.5
0.703
5.82

1.17
8.92
12.6

24.5
12.3
0.219

0.0720
Percent
Errorn
-1
-34
-33
+66
-4
-11
-9
-5
-39
-18

+34
+203
+97

+115
-28
-8

.+6
                                -37-

-------
Table 5.  Continued

Chemical Class/Chemical


F . ESTERS
Ethyl acetate
n-Propyl acetate
i-Propyl acetate
n-Butyl acetate
Ethoxy ethyl acetate
Methyl trifluoroacetate
Methyl formate
Ethyl formate
n-Propyl formate
n-Butyl formate
Methyl acetate
s -Butyl acetate
Ethyl propionate
n-Propyl propionate
Methyl butyrate
Ethyl butyrata
n-Propyl butyrate
n-Butyl butyrate
1012 kOH (cm3molecule~1s"1)

Exper iment a 1
(a)

1.7h'3
ao5h'i
3.09h' 3
4.3h'3
i3>J
	
 -
	
	
	
	
	
	
	
	
	
	
	
(b)

1.6*
3.4*
3.4*
4.2*
13
0.052k'1
0.227k
1.02k
2.38k
3.12k
0.34m
5.5*
2.1m
4.02k
3.04k
4.94k
7.41k
10. 6k
Estimated


1.44
2.89
3.12.
4.28
14.0
0.0518
0.216
1.44
2.89
4.28
0.216
4.99
1.63
3.07
1.48
2.71
4.16
5.55

Percent
Error11


-10
-15
-8
+2
+8
-17
-5
+41 '
+21
+37
-36
-9
-22
-24
-51
-45
-44
-48
                                -38-

-------
Table 5.  Continued
a Experimental data from Atkinson (1986).
b Experimental data from Atkinson (1989) .
c Atkinson (1987) used this value of kOH to derive the substituent
  constant for F[F3C(0)-].
d Experimental data from Rogers (1989).  This value of k0H represents
  the average value of 25.2 and 22.4 x 10~12cm3 molecule'^-s"1 as
  measured with the reference compounds propene and trans-2-butener
  respectively.
e Experimental data from Niki et al. (1987).
f Experimental data from Wallington and Kurylo (1987).
9 Experimental data from Dagaut et al.  (1988).
h Experimental data from Atkinson (1987).
i Used by Atkinson (1987) to derive the substituent factor for acid
  chlorides F[-C(O)C1].
J Used by Atkinson (1987) to derive the substituent factors for
  esters F[-OC(0)R and F[-C(0)OR].
k Experimental data from Wallington et al.  (1988).
1 Used by Leifer to derive the substituent factor F[-OC(0)CF3].
m Experimental value from Wallington et al.  (1988).  The experimental
  data of Campbell and Parkinson  (1978) was not used since the
  experimental method used was probably not valid [Atkinson (1989)].
n Based on the experimental data given in the third column,
  Experimental/(b).
0 Experimental data from Atkinson et al.  (1982).
* Recommended value by Atkinson (1989) with the rationale for the
  recommendation and the uncertainty for the recommendation.
                                -39-

-------
acetyl chloride and Leifer estimated the substituent factor
F[F3C(O)O-] from the kOH data for methyl trifluoroacetate.
These results are

          F[-C(0)C1 ]   = 0.50; F[-OC(0)CF3 ]   = 0.36      (59)

These substituent factors, along with the corresponding E(X)
data, are listed in Table 2.
     Consider the 32 compounds not used to derive the
substituent factors for the carbonyl compounds (i.e., all those
compounds whose values of k0H are not underlined and/or are
below the dashed line).  Four of these compounds had a percent
error greater than +100 [i.e., pentane 1,5-dial (+110);
hydroxyethanal (+132); cyclopentanone (+203); glyoxal (+115)]
and were not used in the calculation of the average percent
error.  Therefore, for the remaining 28 compounds, the average
percent error ranged from +39 to -22 and, thus, ranged from
good to very good.  These results, therefore, confirm the S/R
relationships of Atkinson.  It should be noted that of the four
compounds dropped, three had kOH values which were not
recommended by Atkinson since they only had experimental data
from one literature source.  More experimental kOH data are
needed for these three compounds.
     For the 48 carbonyl compounds remaining (after dropping
the 4 compounds with a percent error greater than +100), the
average percent error ranged from +26 to -19 and, therefore,
ranged from very good to excellent.
                              -40-

-------
III.A.2.d.  Alcohols, Glycols, and Ethers
     For methanol, the simplest member of the aliphatic
alcohols, the hydroxyl radical can react via two pathways:
(1) hydrogen abstraction from the CH3- group; and  (2) hydrogen
abstraction from the -OH group.  Therefore, the reaction of OH
radicals with methanol can be described by the following two
reactions:
                              ka
                          	-  CH30-  +  HOH       (60a)
2 CH3OH  +  2(-OH)
                                 ->  'CH2OH  +  HOH       (60b)

where ka is the rate constant for H-atom abstraction from the
hydroxyl group and kj, is the rate constant for H-atom
abstraction from the CH3- group.  The branching ratio  (BR) for
this reaction scheme is given by the equation

                      BR = ka/(ka + kb)                   (61)

The branching ratio was measured at 298 K recently and it was
found that it was equal to 0.038 [McCaulley et al. (1986)].
Using this branching ratio, Atkinson (1987) found that the
group rate constant for H-atom abstraction from the OH group at
298 K was

            k(-OH) = 0.036 x 10~12 CTO^molecule'is'1      (62)

This value of k(-OH) is lower by a factor of approximately 4
from the value 0.13 obtained previously  [Atkinson  (1986)].
However, the value of k(-OH) given in equation 62 is more
                              -41-

-------
consistent with the C-H and OH bond dissociation energies  in
CH3OH.  Therefore, the value given in equation 62 is listed in
Table 1.
     For the general case for a saturated alcohol,
R-CH(CH3)CH2OH, which contains primary, secondary, and tertiary
C-H groups [i.e., CH3-, -CH2-, and >CH- groups, respectively]
and R is a saturated alkyl group, the hydroxyl radical
reactions can be written as follows:
4 RCHCH2OH
   I    2
   CH3
                                  9H3
                                R-C-CH2OH
                                              HOH
                             >- R-6HCHOH   +  HOH
 CH2
l-CH<
                                R-CHCH2OH  +  HOH
                                  CH3
                                R-CHCH2O  +  HOH
(63a)

(63b)

(63c)

(63d)
From equation 20, for the two reaction pathways, the total rate
constant for OH radical reaction with acyclic alcohols is given
by
                   kOH = k(la) + k(2)
                                                           (64)
     Using equation 11 and the preexponential factor given in
equation 31, Atkinson  (1987) found that

              kOH - 1.89 X 10"18 T2exp(-460/T)             (65)

where k0n is in the units c
     The experimental values of k0n at 298 K for a number of
alcohols (16) and glycols  (2) are listed in Table 6 as obtained
                              -42-

-------
Table 6.  Comparison of Experimental and Estimated Values of XOH
          at 298 K for Alcohols, Glycols, and Ethers and the Percent
          Error [Underlined Values of kOH Were Used by Atkinson
          (1986, 1987) to Derive the Substituent Factors for These
          Classes of Chemicals]
Chemical Class/Chemical
A. ALCOHOLS
Methanol
Ethanol
1-Propanol
2-Propanol
2-Methyl-2-Propanol
1-Butanol
1-Pentanol
2-Pentanol
3-Pentanol
3 -Me thy 1-2 -but ano 1
1-Hexanol
2-Hexanol
1-Heptanol
2 -Chloroethanol
l-Hydroxy-2 -propanone
Cyclopentanol
1012 kOH (cm3molecule"1s~1)
Experimental
(a)

0.90
1^1
Sol
6.2
1.09
7.3
	
	
	
	
	
	
	
1.4
 _
	
(b)

0.932*
3.27*
5.34*
5.21*
1.12*
8.31C
10.8
11. 8d
12. 2d
12. 4d
12. 4d
12. ld
13. 6d
1.4
3.02e
10. 7d
Estimated

0.526-
3.08
4.99
6.63
0.593
6.38
7.77
10.9
12.9
11.0
9.17
12.3
10.6
2.07
2.32
12.7
Percent
Error^

-44
-6
-7
-1-27
-47
-23
-28
-8
+6
-11
-26
+2
-22
-1-48
-23
+ 19
                                -43-

-------
Table 6.  Continued
Chemical Class/Chemical
B. GLYCOLS
1,2-Ethanediol
1 , 2-Propanediol
C. ACYCLIC ETHERS
Dimethyl ether
Di ethyl ether
Di-n-propyl ether
Methyl-t-butyl-ether
Methyl-n-butyl ether
Ethyl-n-butyl ether
Ethyl-t-butyl ether
Methyl -t-amyl ether
Di-n-butyl ether
Di-i-butyl ether
Di-n-pentyl ether
1,1, -Dime thy oxy ethane
D i ethoxymethane
1 , 2-Dimethoxypropane
2 , 2-Dimethoxypropane
2 , 2-Diethoxypropane
2-Methoxyethyl ether
1012 KOH (cm3molecule~1s~1)
Experin
(a)

7.7
12

2.98
13.4
16.8
2.64
	
	
	
	
	
	

	
	
	
	
	
	
Cental
(b)

7.7
12

2.98*
13.3*
17.2*
2.83*
16. 4d
18. lf
6.9f
7.91d
22. 4f
26.09
34. 7d
8.89e
16.8s
14. 3e
3.92e
11. 7e
17. 5e
Estimated

7.42
11.9

1.76
11.5
21.1
2.82
13.6
18.5
7.7
6.13
25.5
30.4
28.2
13.1
16.6
22.9
3.05
12.8
28.1
Percent
Errork

-4
-1

-41
-14
+23
0
-17
+2
+12
-23
+14
+17
-19
+47
-1
+60
-22
+9 '
+ 61
                                -44-

-------
Table 6.  Continued
Chemical Class/ Chemical
1,1, 3 -Tr imethoxypropane
2-Ethoxyethyl ether
Methoxyacetone
2 -Methoxyethanol
2 -Ethoxyethanol
3-Ethoxy-l-propanol
3 -Methoxy-1-butanol
2 -Butoxyethanol
2-Hydroxyethyl ether
D. CYCLIC ETHERS
Ethylene Oxide
1 , 2 -Epoxypropane
1, 2-Epoxybutane
l-Chloro-2 , 3-epoxypropane
Trimethylene oxide
Tetrahydrofuran
1,3-Dioxane
1,4-Dioxane
1,3,5-Trioxane
Oxepane (Hexamethylene oxide)
1012 kOH (cm3molecule~1s"1)
Experimental
(a)
	
	
	
	
	
	
	
	
30

0.07
0.52
2.1
0.44
 _
15
	
	
	
	
(b)
19. 2e
26. 8e
6.77e
12. 5e
15. 4h
22. Oe
23. 6e
18. 6h
30

0.076*
0.52*
2.1
O.SQi
10. 3e
16.1*
9.15e
10. 9e
6.23
15. 4e
Estimated
28.5
37.8
4.87
11.2
16.1
20.9
20.6
23.0
20.6

0.224
0.543
1.70
0.662
3.73
18.3
22.1
26.4
15.3
25.7
Percent
Error*
+48
+41
-28
-10
+ 5
-5
-13
+24
-31

+ 190
+ 4
-19
+ 32
-64
+ 14
1-140
*140
+ 15D
*'
                               -45-

-------
Table 6.  Continued

a Experimental data from Atkinson (1986).
b Experimental data from Atkinson (1989) .
c Experimental data from Wallington and Kurylo (1987a).  The data from
  Campbell et al. (1976) was not used since the validity of the
  experimental method is questionable [Atkinson (1989)].
d Experimental data from Wallington et al. (1988b).
e Experimental data from Dagaut et al.  (1988a)
f Average value from the experimental data of Wallington et al.  (1988b)
  and Bennett and Kerr  (1989).
9 Experimental data from Bennett and Kerr (1989).
n Average value from the experimental data of Hartmann et al.  (1987)
  and Dagaut et al. (1988a).
i Average value from the experimental data of Zetzsch (1980) and Edney
  et al. (1986) assuming kOH = 0.55 x 10~12cm3 molecule~1s~^- of Edney.
J Extrapolated from the experimental data of Zabarnick et al.  (1988).
^ Based on experimental data given in the third column,
  Experimental/(b).
* Recommended value by Atkinson (1989) with the rationale for the
  recommendation and the uncertainty for the recommendation.
                                -46-

-------
from the literature.  In addition, Table 6 lists the
experimental values of kOH for a number of acyclic (26) and
cyclic ethers (10), including hydroxy and chloro substituted
ethers, as obtained from the literature.
     Using the group rate constants for alkanes and k(-OH) for
alcohols from Table 1 and the appropriate substituent factors
F(X) from Table 2, Atkinson carried out a nonlinear least-
squares fit of the experimental k0n data of the alcohols  (i.e.,
the 5 compounds above the line in Table 6.A.) and at 298 K to
equation 28 and found that

                   F(-OH) = 3.4                           (66)

This substituent factor is listed in Table 2.
     Thirteen compounds were not used by Atkinson (1986,  1987)
to derive the substituent factor for the alcohols (i.e., the 11
alcohols listed below the dashed line in Table 6.A. and the 2
glycols in Table 6.B.).  The second-order rate constant k0jj was
estimated using equation 64 (and, therefore, using equations 28
and using 62) and these results are summarized in Tables  6.A.
and B.  The average value of k0H ranged from +19 to -16; and
these results are excellent, thereby confirming the S/R
relationships of Atkinson.
     The average value of kOH for all 18 alcohols ranged  from
+20 to -19 so that these results are also excellent.
     Using the appropriate group rate constants and substituent
factors, Atkinson  (1986) carried out a nonlinear least-squares
fit of the experimental data  at 298 K for the first four

                              -47-

-------
ethers listed in Table 6.C. and found that

                      F(-O-) = 6.1                        (67)

     Atkinson (1987) reevaluated the S/R relationships of the
ethers.  For 1,3,5-trioxane, Atkinson indicated that the ring
strain energy is approximately 6 kcal/mol, the same as the ring
strain energy of cyclopentane.  Therefore, kOH was estimated
for this cyclic ether using the ring strain factor F(5) =0.80
(Table 2) and Atkinson found that kOH = 75 x 10~12
cm3molecule~1s~1.  Even with this ring strain factor, the
percent error was too high  (+850).  It appears that 1,3,5-
trioxane is much less reactive than implied by the presence of
the two substituent ether groups  (-0-) per methylene group
(-CH2-).  Based on these results and a reevaluation of the k0H
data for all the ethers listed in Tables 6.C. and D., Atkinson
(1989a) indicated that for the ethers

                      F(-O-) = 6.1                        (68)

                        -0-) = 1.0                        (69)

                  F(-CH2-0-) =4.5                        (70)

                  F(C-0-) = 4.5                          (71)

and these results are summarized  in Table 2.
     Using the appropriate substituent factors and group rate
constants, kOH was estimated for  all 36 ethers listed in Tables
6.C. and D. and these results are summarized in the fourth
column of this table.  The percent error for each compound is
                              -48-

-------
listed in the sJl column of this table.  Inspection of all
these data indicated that 4 compounds had an error greater than
+100 [ethylene oxide (+190); 1,3-dioxane (+140); 1,4-dioxane
(+140); 1,3,5-trioxane (+150)].  Excluding these 4 compounds,
the remaining 32 compounds had a percent error which ranged
from +27 to -22.  These results are very good, indicating that
the S/R relationships for the ethers are very good.  However,
it should be noted that all these compounds were used to derive
the substituent factors for the ethers.  Therefore,
considerably more experimental kOH data are needed on
additional ethers to confirm the S/R relationships of Atkinson.
In addition, more experimental data is needed for the 4
compounds with percent error > +100 to determine why they had
such a large percent error.

III.A.2.e.  Nitrates and Nitriles
     The experimental values of kOH at 298 K for 17 alkyl and
cycloalkyl nitrates and 2 alkyl nitriles are listed in Table 7
as obtained from the literature.  The experimental values of
kOH listed in the third column represent the best available
values for these compounds as obtained from Atkinson (1989) and
the literature.  Atkinson  (1987, 1989) indicated that the
experimental JCQH data for methyl and ethyl nitrate from Kerr
and Stocker (1986) were systematically high and should be used
with caution.  Only for acetonitrile did Atkinson  (1989) list a
recommended value of kOH at 298 K with the rationale and
uncertainty for this recommendation.
                              ~49~

-------
Table 7.  Comparison of Experimental and Estimated Values of
          koH at 298 K for Nitrates and Nitriles and the
          Percent Error [Underlined Values of kOH Were Used
          by Atkinson (1986, 1987) to Derive the Substituent
          Factors for the Nitrates and Nitriles]
Chemical Class/Chemical
A. NITRATES (ACYCLIC)
2-Propyl nitrate
1-Butyl nitrate
2 -Butyl nitrate
2-Pentyl nitrate
3-Pentyl nitrate
2-Methyl-3-butyl nitrate
2,2-Dimethyl-l-propyl nitrate
2-Hexyl nitrate
3-Hexyl nitrate
2-Methyl-2-pentyl nitrate
3-Methyl-2-pentyl nitrate
3-Heptyl nitrate
3-Octyl nitrate
Methyl nitrate
Ethyl nitrate
1-Propyl nitrate
1012 kOH (cm3molecule~1s~1)
Excerimental
(a)

0.18
1.39
0.67
1.83
1.10
1.72
0.85
3.13
2.66
1.71
3.01
3.64
3.82
	
	
	
(b)

0.41C
1.78
0.92
1.85d
1.12d
1.72e
0.85e
3.17d
2.70d
1.72e
3.02e
3.69e
3.88d
0.034f
0.499
0.67h
Estimated

0.416
1.79
0.905
2.06
1.42
1.39
0.752
3.45
2.58
1.68
2.63
3.97
5.37
0.0259
	
0.632
Percent
ErrorJ

+1
-i-l
-2
+ 11
+27
-19
|
1
-12
+ 9
-4
-2
-13
+ 8
+ 38
-24
	
-6
                              -50-

-------
Table 7.  Continued
Chemical Class/Chemical
B. NITRATES (CYCLIC)
Cyclohexyl nitrate
C . NITRILES
Acetonitrile
Propionitrile
1012 kOH (cm3molecule"1s~1)
Exper iment a 1
(a)
3.29
0.021
0.19
(b)
3.30e
0.0214*
0.1941
Estimated
5.38
0.0202
0.189
Percent
ErrorJ
+63
-6
-3
a Experimental data from Atkinson  (1986).

b Experimental data from Atkinson  (1989).

c Experimental data from Atkinson  and Aschmann  (1989).

d Experimental data from Atkinson  et al.  (1982a).

e Experimental data from Atkinson  et al.  (1984b).

f Atkinson  (1987) reported a value of kOK = 0.034 x  10"12  and  0.38 x
  10~12cm3 molecule'is""1 from Gaffney et al.  (1986)  and Kerr and  Stocker
  (1986), respectively.  Atkinson  (1987) used the value of 0.034  x 10~12
  since it was more consistent with the entire  set of k_H  data used to
  develop the S/R relationships and the value from Kerr and Stocker was
  systematically too high.  Atkinson  (1989) also tentatively preferred
  the value of kOH from Gaffney et al.  (1986) since  the value  from
  Kerr and Stocker was systematically too high.

9 Experimental data from Kerr and  Stocker  (1986).  Atkinson (1987, 1989)
  did not accept this data since the results were systematically  too
  high.

n This value of kOH represents the average value from the  experimental
  data of Kerr and Stocker  (1986)  and Atkinson  and Aschmann (1989).

i Experimental data from Harris et al.  (1981).

J Based on the experimental data given  in the third  column,
  Experimental/(b).

* Recommended value by Atkinson  (1989)  with the rationale  for  the
  recommendation and the uncertainty for the recommendation.
                                -51-

-------
     Atkinson (1986) analyzed the k0n data at 298 K for the
first 13 alkyl nitrates listed above the dashed line in Table
7.A. (i.e., the underlined values of kOH in column 2) and for
cyclohexyl nitrate in Table 7.B.  Using the appropriate group
rate constants and substituent factors from Tables 1 and 2,
respectively, Atkinson carried a nonlinear least-squares fit of
the experimental kOH data of the nitrates to equations 28 and
43  (for the acyclic and cyclic nitrates, respectively) and
derived substituent factors for the nitrates.  Atkinson (1987)
repeated the analysis of the kOH data (excluding the data of
Kerr and Stocker (1986) for methyl and ethyl nitrate) and found
that the substituent factors for the alkyl nitrates were

        F(-CH2ON02)  F(>CHON02) = F(>CON02) = 0.21      (72)

                          F(-ON02) = 0.10               (72a)

Recently, Atkinson  (1989a) repeated the analysis of the kOH
data for the alkyl nitrates (excluding only the data for ethyl
nitrate) and obtained refined values of the substituent factors
given by

        F(-CH2ON02) = F(>CHON02) = F(CON02) = 0.30      (73)

   .                   F(-ON02) = 0.18                (73a)

     The second-order rate constant kOH for all 16 alkyl
nitrates (excluding ethyl nitrate) was estimated in the
standard manner and these results are summarized in Table 7
along with the percent error.  The average percent error ranged

                              -52-

-------
from +20 to -10 and these results ranged from excellent to
superb.
     The only compound not used to derive these substituent
factors was 1-propyl nitrate.  The estimated value of KOH
this compound was 0.632 x 10~12cm3 molecule~1s~1 and the
percent error was -6 which was excellent.  However/ more
experimental kOH data are needed for other alkyl nitrates to
confirm the S/R relationships of Atkinson.
     In a similar manner, Atkinson (1986) analyzed the k0H data
at 298 K for two nitriles listed in Table 7.C. and derived the
following substituent factors for this class of compounds:

                     F(-CN) = 0.14                        (74)

                  F(-CH2CN) = 0.50                        (75)

and these results are summarized in Table 2.  The rate constant
kOH was then estimated in the standard manner for the two
nitriles using equation 28 and these results are listed in
Table 7 along with the percent error.  The average percent
error for these two nitriles is -5 which is superb.  More
experimental k^H data are needed for additional alkyl nitriles
to confirm the S/R relationships of Atkinson.

III.A.2.f.  Olefins, Diolefins, Alkynes, and Aromatic
            Compounds
     Atkinson  (1986, 1987) analyzed the kinetic data at 298 K
for H-atom abstraction from compounds containing the following
carbon-carbon unsaturated groups:  (1) olefins such as -?CH=CH2,
-CH=CH-, etc.;  (2) conjugated diolefins such as -CH=CH-CH=CH-,
                              -53-

-------
-CH=CH-C=CH2/ etc.; (3) alkynes such as -CsC-H; allenes such as


>C=C=C<; and (4) aromatic compounds such as C6H5-, etc.  For


all practical purposes, Atkinson (1986, 1987) concluded that


the rate constant for H-atom abstraction from the above


functional groups was essentially zero.  Therefore, from


equation 20, one obtains



vn TTOQ rm - vfH~atom abstraction from carbon-carbon] _    .....
k(l,UNS CH) - "Lunsaturated functional groups        J ~   (76)



Even at elevated temperature up to 500 K, k(l,UNS CH) was


essentially zero [Atkinson (1987)].  In addition, Atkinson


(1987) concluded that the substituent factors for carbon-carbon


unsaturated groups were approximately 1.0; therefore



           F(>C=C<) = F(-CsC-) = F(C6H5-) =1.0



All the above results are summarized in Tables 1 and 2.



III.A.3.  Summary


     Table 8 summarizes the average percent error in the


estimation of kOH for H-atom abstraction from C-H and -OH


groups by hydroxyl radicals at 298 K for chemicals within each


of several classes of organic chemicals and for all chemicals


within all the classes of chemicals as obtained from Tables


3-7.  The total rate constant for H-atom abstraction kQjj was


estimated for a total of 207 chemicals and these results are


compared to the experimental values.  Only 9 chemicals had a


percent error greater than +100 [pentane 1,5-dial  (+110);


hydroxyethanol  (+132); cyclopentanone  (+203); 1,1,1-



                              -54-

-------
Table 8.  Summary of the Average Percent Error in kOH fr
          H-Atom Abstraction From C-H and OH Groups at 298 K
          for Chemicals Within Several Classes of Chemicals and
          for All Chemicals in These Classes
Chemical Class3
Alkanes [Acyclic (32)
and Cyclic (18) ]
Haloalkanes, Acyclic
(32)c
Carbonyls (52)d
[Aldehydes (11) ; Ketones
(19); a-Dicarbonyls
(3) ; Acyl Halides (1) ;
Esters (18)]
Alcohols (16); Glycols
(2);
Ethers [Acyclic (26) ;
and Cyclic (10)]
Nitrates [Acyclic (16) f
and Cyclic (1)]
Nitriles, Acyclic (2)
All chemicals not used
to derive the substi-
tuent constants and
group rate constants
All Chemicals (207)
No. of
Chemicals*3
50
30
48
18
32
16
2
74
196
Average Percent Error
From
+12
+21
+26
+20
+27
+20
 .
+26
+21
TO
-10
-28
-19
-19
-22
-10
-5
-20
-18
a The numbers in parentheses represent the total number of
  chemicals in which k, was estimated.
                      UH

b These numbers represent the number of chemicals used to
  calculate the average percent error.
                              -55-

-------
Table 8.  Continued
c One of these chemicals had a percent error greater than 100
  1,1,1-trifluoroethane (+440)] and was not used to determine
  the average percent error.  The second chemical, trifluoro-
  methane, did not have a reliable experimental value of kOH
  and therefore was not used to determine the average percent
  error.

d Four chemicals had a percent error greater than 100 [pentane-
  1,5-dial (+110); hydroxyethanal (+132); cyclopentanone
  (+203); glyoxal (+115)] and were not used to determine the
  average percent error.

e Four chemicals had a percent error greater than 100 [1., 3-
  dioxane (+(140); 1,4-dioxane (+140); ethylene oxide (+220);
  1,3,5-trioxane  (+150)] and were not used to determine the
  average percent error.

f One chemical, ethyl nitrate, had unreliable kOH data and was
  not used to determine the average percent error.
                              -56-

-------
trifluoroethane (+440); glyoxal (+115); 1,3-dioxane (+140);
1,4-dioxane (+140); 1,3,5-trioxane (+150)  and ethylene oxide
(+220)].   Two chemicals (trifluoromethane and ethyl nitrate)
had unreliable experimental kOH data.  Therefore, the kOH data
for these 11 chemicals were not included in the determination
of the average percent error for certain classes of chemicals
and for all chemicals.  It should be noted that the value of
+100 was chosen so that only a minimum number of chemicals
would be dropped from the total number of chemicals used to
obtain the average percent error.  See Summary Tables 8, 17,
21, 25, 26, and Section III.E.  The range in the average
percent error for each class ranged from superb to very good.
The average percent error for the 74 chemicals not used by
Atkinson to derive the group rate constants and substituent
factors ranged  from +26 to -20.  These results, therefore,
ranged from very good to excellent and confirm most of the S/R
relationships of Atkinson.  For all 196 chemicals, the average
percent error ranged from +21 to -18; and these results ranged
from very good to excellent.  More experimental kOH data,
however, are needed to determine why the nine chemicals listed
above had a large percent error  (> +100 percent) and to confirm
the S/R relationships for ethers, nitriles, a-dicarbonyls, acid
chlorides, and glycols.  In addition, more reliable
experimental kOH data are needed for trifluoromethane and ethyl
nitrate.
                              -57-

-------
III.B.  Addition of Hydroxyl Radicals to Olefinic, Conjugated

        Diolefinic, 1,2-Diolefinic Compounds and Alkynes and

        the Estimation of kOH





III. B.I.  Formulation of the Structure/Reactivity Relationships



     Atkinson (1986, 1987) analyzed the kinetic data for OH



radical reaction with olefins and acetylenes.  For these two



classes of compounds with the following general structures





                      R1R2C=CR3R4                          (78)





                        R5C5CR6                            (79)





(where R^ is an alkyl group or H) , the total rate of hydroxyl



radical reaction, kQjj , is: (1) a function of H-atom



abstraction by OH radicals from C-H groups in the alkyl groups



R^, from the groups =CH2, =CH-, etc. in olefins and from the



groups sc-H; and (2) the addition of OH radicals to the



isolated unsaturated carbon-carbon groups.



     H-atom abstraction by hydroxyl radicals from C-H groups



has already been described in Section III. A.  The addition of



OH radicals to the unsaturated carbon-carbon groups in alkenes



and alkynes can be represented by the following reactions:






                             ?H
  2 R1CH=CH2  + 2('OH) - * RiCHCH^   + R1CHCH2OH + 2 HOH   (80)
                             OH            OH

  2 R2CH=CHR3 + 2 (-OH) -  R2CHCHR3  + R2CHCHR3 + 2 HOH




                             9H

  2 R4C=CH    + 2 (-OH) - * R4C=CH    + R4C=CHOH  + 2 HOH   (82)




                             2H            2H
  2 R5C3CR6   + 2 (-OH) -  R5C=CR6   + R5C=CR6   + 2 HOH   (83)
                              -58-

-------
where R^ are all alkyl substituents.  Similar reactions can be
written for conjugated diolefins.
     To a good approximation, the addition of OH radicals to
unsaturated carbon-carbon groups can be described by the simple
Arrhenius equation (equation 10) at temperatures  500 K
[Atkinson (1987a)].  The energy of activation for these systems
is on the order of -1 kcal/mol  [Atkinson (1986, 1987)].
Atkinson developed S/R relationships at 298 K which are based
on the number of unconjugated unsaturated carbon-carbon groups
or on the number of nonaromatic conjugated unsaturated carbon-
carbon groups in a molecule and on the degree, identity, and
configuration of substitution around these groups [Atkinson
(1986, 1987, 1987b, 1988, 1988a)].  For example, cis-2,5-
hexadiene, with molecular structure
                CH2=CH-CH2     /CH3
                          ">=C                          (84)
                          H     H

contains a cis-dialkyl substituted alkene and a monosubstituted
alkene.  To a good approximation, Atkinson indicated that the
overall rate constant for OH addition to these two isolated
double bond groups is the sum of the rate constants for cis-2-
butene and propene.
     For dialkenes with conjugated carbon-carbon double bond
groups, there is a strong interaction between the two double
bonds  (i.e., resonance).  Therefore, for conjugated dialkenes,
Atkinson considered the entire  conjugated system
                             I  i
                          >C=C-C=C<                       (85)
                              -59-

-------
as a single unit.  For example, 3-methylene-l, 6-octadiene, with


molecular structure




                         CH2        CH3

                         U          '
                  CH2=CH-C-CH2CH2CH=C-CH3                 (86)




                                            CH2
                                            II
contains the conjugated diene system CH2=CH-C-  and an isolated


double bond group R1CH=CR2R3 (where R^ is an alkyl group) .


Thus, to a good approximation, the overall rate of OH radical


addition to the carbon-carbon double bonds is the sum of  the


rate constants for 2-methylbutadiene and trimethylethene.


     Alkynes and 1,2-dialkenes are treated as separate carbon-


carbon unsaturated bond groups.


     For the total rate of hydroxyl radicals with alkenes,


dienes, alkynes, etc., k0jj , from equation 20, is given by the


equations
                      kOH = k(l) + k(3)                     (87)




                      kOH = Ml) + *add,nar                 (88)




where:  k(l) represents the rate constant for the H-atom


abstraction from C-H groups (equation  12); k(3) is given by the


equation




                      M3) = kadd,nar                       (89)




and kadd nar represents the rate constant for OH radical


addition to nonaromatic unsaturated carbon-carbon groups


 (equation  14) .  It  should be noted that H-atom abstraction  f rc^i




                              -60-

-------
the unsaturated groups =CH2/ =CH-, etc. is essentially  zero  up
to 500 K {i.e., k(l, UNS CH) = 0, Table 1} [Atkinson  (1986,
1987) ].
     Atkinson  (1986, 1987, 1987b, 1988a), based on a  detailed
study of the kinetic data for OH radical reaction with
compounds containing nonaromatic unsaturated carbon-carbon
groups at 298 K, formulated S/R methods for estimating  ka(jd  nar
according to the relationship

     kadd,nar =  E  kadd,nar + E kadd,nar + E  kadd,nar       (90)

where:  the first term represents the  contribution from OH
radical addition to isolated olefinic  systems and is  described
by the subscript add,nar and the superscript is on the  rate
constant k; the second term represents the contribution from OH
radical addition to nonaromatic conjugated olefinic groups and
is described by the subscript  add,nar  and the superscript co on
the rate constant k; and the last term represents the
contribution from other unsaturated carbon-carbon groups such
as -CaC- and >C=C=C< and  is described  by the subscript  add,nar
and the superscript ou on the  rate constant k.
     The first term in equation 90, for isolated carbon-carbon
double bond groups, can be represented by the equation

                 E "idd.nar  = E *?              OD
         i Q
where:  kg  represents the group rate  constants at 298  K for OH
                              -61-

-------
radical addition to isolated >C=C< groups and the numerical
values for the various types of unsaturated carbon-carbon
groups are listed in Table 9 (derived from the experimental kOH
data of specific alkenes as listed in the footnotes of this
table); the terms C(X) and C(Y) represent the substituent
factors on the unsaturated groups for the substituents X and Y
and the numerical values for these factors are listed in Table
10 (derived from the experimental KQH data of specific alkenes
as listed in the footnotes of this table) .
     In a similar manner, the second term in equation 90, which
represents OH radical addition to nonaromatic conjugated
carbon-carbon double bond groups, is given by the equation
                                                            02)
where:  kg represents the group rate constants at 298 K for OH
radical addition to nonaromatic conjugated carbon-carbon double
bond groups such as -CH=CH-CH=CH- .  The numerical values of kQO
for these groups are listed in Table 11 (derived from the
experimental kOH data of specific conjugated dienes at 298 K as
indicated in the footnotes of this table) ; and the substituent
factors C(.X) and C(Y) , for substituents X and Y, are listed in
Table 10.  Conjugated aryl-alkene systems are treated by
                              -62-

-------
Table 9.  Group Rate Constants kg3 in Equation 91 for Hydroxyl
          Radical Addition to Isolated Olefinic Groups at 298 K


                                              1012kjs
          Structure3                      (cm3 molecule~1s~1)
           CH2=CH-R                              26.3b

               C                                 51.4C
                                                 se.i


                                                 ,. _e
            trans                                63.7

           -CH-C'*                               86.9f


           5X5
a R in these structures represent alkyl groups

b Derived from the experimental data of propene with k0H ~ 26.3
  x 10~12cm3 molecule"^"1 at 298 K [Atkinson (1986)].

c Derived from the experimental data of 2-methylpropene with
  kOH = 51.4 x 10~12cm3 molecule~1s~1 at 298 K [Atkinson
  (1986)].

d Derived from the experimental data of cis-2-butene with
  kOH = 56.1 x 10~12cm3 molecule"1s~1 at 298 K [Atkinson
  (1986)].

e Derived from the experimental data of trans-2-butene with
  kOH = 63.7 x 10~12cm3 molecule~1s"1 at 298 K [Atkinson
  (1986)].

f Derived from the experimental data of 2-methyl-2-butene with
  kOH = 86.9 x 10~12cm3 molecule~1s"1 at 298 K [Atkinson
  (1986)].

9 Derived from the experimental data of 2,3-Dimethyl-2-butene
  with kOH = 110 x 10"12cm3 molecule"^"1 at 298 K [Atkinson
  (1986)].
                              -63-

-------
Table 10.  Substituent Factors C(X) in Equations 91, 92, and 93
           for Substituent X on Nonaromatic Unsaturated Carbon-
           Carbon Groups at 298 K

                                          Substituent
Group
-Ra
-F
-Cl
-Br
-CH2C1
-CN
-CH(O)
-C(0)CH3
-OCH3
=0 (0)
a R is alkyl group. If R is a phenyl
is also equal to 1.00 [see Table 23,
Factors cm
1.00
0.4b
0.20b
0.26b
0.76
0.15d
0.26e
0.91f
1.39
1.0n
group, then C(C6H5-)
C. ALKENYLBENZENES] .
b Derived from the best available k0n data for CH2*=CHF,
CH2=CHC1, CH2=CHBr, CH2=CF2 , CHC1=CC12, CC12=CC12, and
CFC1=CF2 [Atkinson (1986, 1987)].
c Derived from fitting the best available experimental kOH data
  and calculated rate constants for cis- and trans- 1,3-
  dichloro-1-propene and 2-chloromethyl-3-chloro-l-propene
  [Atkinson  (1986, 1987)].
  Derived from the best available k0H data of CH3CsN [Atkinson
  (1986)].

e Derived from the best available k0jj data for CH2=CHCHO,
  CH3CH=CHCHO, and CH2=C(CH3)CHO [Atkinson (1986)].

f Derived from the best available kpH data for CH2=CHC(0)CH3
  and cis- and trans-3-hexene-2.5-dione [Atkinson  (1986)].

9 Derived from the best available kOH data for CH2=CHCOCH3
  [Atkinson  (1986)].

n Derived from the best available kOH data for a series of
  ketenes [Atkinson  (1987)].
                              -64-

-------
Table 11.  Group Rate Constants kg in Equation 92 for
           Hydroxyl Radical Addition to Conjugated Nonaromatic
           Functional Groups at 298 K
  Set
  No.
No. of
Alfcyl
Groups
 (R)
 Structure3
10
                                                 12
                    (cm3molecule~1 s-
                      CH2=CH-CH=CH-R

                      CH2=CH-C=CH2
                                       1051
 II
CH2=CH-C=CHR

CH2=C-CH=CHR



R-CH=CH-CH=CH-R
                                       135
III
                      CH2=C-p=CHR
                          R R

                      R-CH=CH-C=CHR
                                       180C
 IV
                      R-CH=p-9=CHR
                           R R
                                       230d
                              -65-

-------
Table 11.  Continued
a R is an alkyl Group.

b Derived from the average value of kOH for cis-1,3-pentadiene,
  2-methyl-1,3-butadiene and tans-l,3-hexadiene [Atkinson
  (1986)].

c Derived from the average value of kOH for cis-, trans-2f4-
  hexadiene, 2-methy1-1,3-pentadiene, 4-methyl-l,3-pentadiene,
  2,3-dimethyl-1,3-butadiene, 1,3-cyclohexadiene and 1,3-
  cycloheptadiene [Atkinson  (1986)].

d Derived by multiplying the rate constant for the two
  substituent structures by a factor of 1.3 and  (1.3)(1.3)
  (i.e., Ill = (1.3)(135) - 176 = 180; IV - (1.3)(1.3)(135) =
  176 - 180) [Atkinson  (1986)].
                              -66-

-------
considering OH radical addition to the >C=C< and aryl groups
separately.  See Section III. 0.2. a. and Table 23, C. ALKENYL-
BENZENES .
     Finally, the third term in equation 90, for other
nonaromatic unsaturated carbon-carbon groups, is given by the
equation

                                                           (93)
where:  k,u represents the group rate constants at 298 K for OH
radical addition to nonaromatic unsaturated groups such as
-esc-, >c=C=C< , etc. and the numerical values for various
types of these groups are listed in Table 12 (derived from the
experimental kOH data of specific 1,2-dienes and alkynes at
298 K as indicated in the footnotes of this table) ; and the
substituent factors C(X) and C(Y), for the substituents X and
Y, are listed in Table 10.

III.B.2.  Estimation of kOH for Several Classes of Chemicals at
          298 K and a Comparison of These Results with the
          Experimental Data
III.B.2. a.  Unsubstituted Alkenes
     Table 13 lists the pertinent kOH data at 298 K for the
unsubs.tituted alkenes as obtained from the literature.  This
table is in exactly the same format as Table 3. A. and the data
in each column is the same as that described in the first
paragraph of Section III. A. 2. a. i.
                              -67-

-------
Table 12.  Group Rate Constants k2u in Equation 93 for
           Hydroxyl Radical Addition to Alkynes and Allenes
           at 298 K


                                              10-12kou
                                                    *J ^, 1 , 1
             Structure3                   (cm3molecule  s  )
               CH2=C=CHR                         31b








               H-CSC-R                            6.4d

               R-CsC-R                           29e
a R in these molecular structures represent alkyl groups.

b Derived from the average value of the kOH data of 1,2-
  butadiene and 1,2-pentadiene [Atkinson (1986)].

c Derived from the experimental kOH data of 3-methyl-l,2-
  butadiene [Atkinson (1986)].

d Revised from Atkinson (1986) using the kOH data of Atkinson
  and Aschmann (1984) for propyne and 1-butyne [Atkinson
  (1987)].

e Derived from the kOH data of Hatakeyama et al. (1986) for 2-
  butyne [Atkinson (1987)].
                              -68-

-------
Table 13.  Comparison of Experimental and Estimated Values of
           kgu for Unsubstituted Alkenes and the Percent Error
           [Underlined Values of kOH Were Used by Atkinson (1986)
           to Derive the Group Rate Constants for Alkenes]
Chemical Class/Chemical
A. ACYCLIC ALKENES
Propene
cis-2-Butene
trans- 2 -Butene
2 -Methy Ipropene
2-Methyl-2-butene
2 , 3-Dimethyl-2-butene
1 -Butene
1-Pentene
cis-2-Pentene
trans-2 -Pentene
2-Methyl-l-butene
3 -Methy 1-1-butene
1-Hexene
2 -Methy 1- l-pntene
2-Methyl-2-pentene
trans-4-Methyl-2-pentene
3 , 3-Dimethyl-l-butene
1012 )COH (cm3molecule"1s~1)
Experimental
(a)

26.3
56.1
63.7
51.4
86.9
110.
31.4
31.4
65.1
67
	
31.8
37
62.6
88.8
60.8
28.4
(b)

26.3*
56.4*
64.0*
51.4*
86.9*
110*
31.4*
31.4*
65. 7C
66. 9d
60.6
31.8*
35. 2e
62. 6f
89. lf
60. 5f
28.59
Estimated

26.4
56.4
64.0
51.7
87.3
111
27.3
28.6
57.3
64.9
52.6
28.5
30.0
53.9
88.2
66.0
26.9
Percent
Error0

0
0
0
+1
0
+1
-13
-9
-13
-3
-13
-10
-15
-14
-1
+9
-6
                                -69-

-------
Table 13.  Continued
Chemical Class/Chemical
1-Heptene
2 , 3-Dimethyl-2-pentene
trans-4 , 4-Dimethyl-2-pentene
1 , 4-Pentadiene
trans-1 , 4-Hexadiene
1,5-Hexadiene
2-Methyl-l , 4-pentadiene
2-Methyl-l , 5-hexadiene
2 , 5-Dimethyl-l , 5-hexadiene
B. CYCLIC ALKENES
Cyclopentene
Cyclohexene
1 , 4-Cyclohexadiene
Cycloheptene
1-Methyl-cyclohexene
Bicyclo [2.2.1] -2-heptene
Bicyclo [ 2 . 2 . 1 ] -2 , 5-heptadiene
Bicyclo [2.2.2] -2-octene
ot-Pinene
0-Pinene
1012 KOH (cm3molecule~1s"1)
Experimental
(a)
40
108
54.8
53.3
91.0
62.0
79
96
120

67
67.4
99
74.1
95
49.1
120
40.6
53.2
	
(b)
38. 3h
103f
54. 5f
53.3d
90. 6d
62. Od
78. 8d
96. ld
120d

65. 51
67.7*
99. 5J
74. 4k
94. 41
49. 3k
120k
40. 8k
53.7*
78.9*
Estimated
31.4
111
64.4
53.4
91.0
54.8
78.7
80.0
105

58.9
61.1
114
62.5
92.0
62.7
116
67.8
96.9
54.2
Percent
Error0
-18
+8
+18
0
0
-12
0
-17
-13
I

-10
-10
+ 15
-16
-3
*27
-3
.66
30
- J 1
                                -70-

-------
Table 13.  Continued
Chemical Class/ Chemical
<|-Limonene
A3-Carene
y-Terpinene
1012 KQH (cm3molecule~1s~1)
Experimental
(a)
169
87.0
176
(b)
160m
87. 8n
177n
Estimated
145
87.5
178
Percent
Error0
-9
0
+1
a
b
c
e

f
1
m

n
o
  Experimental data from Atkinson  (1986).
  Experimental data from Atkinson  (1989).
  Average value of the experimental data of Ohta  (1984) and Wu et al.
  (1976).
  Experimental data from Ohta  (1983).
  Average value from the experimental data of Wu  et al. (1976) and
  Atkinson and Aschmann  (1984).
  Experimental data from Ohta  (1984).
  Experimental data from Wu et al.  (1976).
  Average value from the experimental data of Darnall et al.  (1976) and
  Atkinson and Aschmann  (1984).
  Average value from the experimental data of Atkinson, Aschmann, Carter
  (1983) and the relative rate data with cyclohexene of Rogers (1989).
  Average value from the experimental data of Atkinson, Aschmann, Carter
  (1983) and Ohta  (1983).
  Experimental data from Atkinson, Aschmann, Carter  (1983).
  Experimental data from Darnall et al.  (1976).
  Average valu* from the experimental data of Winer et al.  (1976) and
  Atkinson, Aschmann, Pitts  (1986).
  Experimental: data from Atkinson, Aschmann, Pitts  (1986).
  Based on th experimental data given  in the third column,
  Experimental/(b).
  Recommended value by Atkinson  (1989)  with the rationale  for the
  recommendation and the uncertainty for the recommendation.
                                -71-

-------
     The underlined values of kOH in the second column,
representing the first 6 alkenes above the dashed line, were
used by Atkinson (1986, 1987) to derive the group rate
constants for these compounds (Table 9).  The substituent
factors C(R) for alkyl and phenyl groups were set equal to 1.00
(Table 10).
     The experimental values of kOn at 298 K are listed in
Table 13 for 39 unsubstituted alkenes  (26 acyclic and 13
cyclic) as obtained from Atkinson (1986).  Using equation 91,
the appropriate group rate constants ks from Table 9 and
the substituent factors C(R) = 1.00, Table 10, ki|^ nar was
calculated for each alkene.  This result is substituted in
equation 90 to obtain *add,nar'  Ifc should be noted that for
these alkenes, k^dd nar and kadd nar are zer*   Tne H-atom
abstraction rate constants for C-H groups in each
alkene,[k(l)], were estimated by the methods described in
Section III.A.  The total rate constant kOH for each alkene is
then the sum of k(l) and kad(j nar, equation 88.  These results
are listed in Table 13 along with the percent error.  For the
34 acyclic and cyclic alkenes listed below the dashed line, the
average percent error ranged from +16 to -11; and these results
therefore,, are excellent, confirming the S/R relationships of
Atkinson.  For all 39 alkenes, the percent error was +13 to -11
which is excellent.
                              -72-

-------
III.B.2.b.  Substituted Alkenes
     The experimental values of kOH at 298 K for 24 substituted
acyclic alkenes are listed in Table 14 as obtained from the
literature.
     This group of 24 compounds can be divided into the
following categories:  12 halogenated alkenes; 10 carbonyl
substituted alkenes; aeryIonitrile; and methyl vinyl ether.
Using equation 91 and the appropriate group rate constants and
substituent factors from Tables 9 and 10, respectively,
*add nar was estimated for each substituted alkene.
Substituting equation 91 in 90 yields kadd nar*  Again, it
                                                     CO
should be noted that for these substituted alkenes, kadd nar
and kad
-------
Table 14.  Comparison of Experimental and Estimated Values of kOH
           for Substituted Alkenes at 298 K and the Percent Error
           [Underlined Values of kOH Were Used by Atkinson (1986,
           1987) to Derive the Substituent Factors for these
           Chemicals]
Chemical Class/ Chemical
A. HALOALKENES
Vinyl fluoride
Vinyl chloride
Vinyl bromide
1, 1-Dif luoroethene
Trichloroethene
Tetrachloroethene
cis-1 , 3-Dichloro-l-propene
trans-1 . 3-Dichloro-l-propene
3 -Chloro-l-propene
2- (Chloromethyl) -3-chloro-l-
propene
cis-1 , 2-Dichloroethene
trans-1 , 2-Dichloroethene
B. a,/3-UNSATURATED CARBONYLS
Acrolein (2-Propenal)
trans-Crotonaldehyde ftrans-
2-ButenalX
Methacrolein (2-Methyl-2-
propenal)
Methyl vinyl ketone
Ketene
1012 JCQH (cm3molecule~1s~1)
Experimental
(a)

5.56
6.60
6.81
8.10
2.36
0.167
8.45
14.4
11
33,5
2.38
1.80

19.6
M
30.7
18.5
	
(b)

5.56
6.60
6.81C
-d-
2.36*
0.167*
8.41e
14. 3e
17*
33. 5e
2.38e
1.80e

19.9*
36*
33.5*
18.8*
17.3f'
-------
Table 14.  Continued
Chemical Class /Chemical
Methyl ketene
Ethyl ketene
Dimethyl ketene
c isT- 3 -Hexene- 2 , 5-dione
trans-3-Hexene-2 , 5-dione
C. NITRILO ALKENES
Aery Ion itrile (Cyanoethene)
D. ALKOXY ALKENES
Methyl vinyl ether
1012 kOH (cm3molecule~1s""1)
Experimental
(a)
	
	
	
63
53

-1

33t5
(b)
70f 'n
118*'9
107f<9
63. 11
53. 11

4.13

33.5
Estimated
87.0
87.9
110
46.7
53.0

3.95

35.1
Percent
Errork
+24
-26
+3
-26
0

-4

+5
c
d
e
  Experimental data from Atkinson  (1986) .
  Experimental data from Atkinson  (1989).
  Experimental data from Perry, Atkinson, Pitts  (1977a) .
  Experimental data is probably not reliable  [Atkinson  (1989)].
  Experimental data from Tuazon et al.  (1988).   This data  is preferred
  since the experiments avoided or have  taken  into account the  side
  reactions of the Cl atom with the reference  compounds  [Atkinson
  (1989)].
  Used by Atkinson  (1987) to derive the  substituent constant C(=O),
  Table 2.
  Experimental data from Hatakeyama et al.  (1985) .
  Average value  from the data of Hatakeyama et al.  (1985).
  Experimental data from Tuazon et al.  (1985).
  Average value  from the experimental data of  Harris et  al.  (1981) and
  Zetsch  (1983)  as reported in Atkinson  (1989).
  Based on the experimental data given in the  third column,
  Experimental/ (b) .
  Recommended value by Atkinson  (1989) with the  rationale  for the
  recommendation and the uncertainty for the  recommendation.
                                -75-

-------
2,5-dione  were not used to derive the substituent factors.
The average percent error for these 4 compounds ranged from +21
to -16 which ranged from very good to excellent.  More
experimental kOH data are needed for a number of additional
compounds to confirm the S/R relationships of Atkinson.
Excluding the chemicals 1,1-dichloroethene and ketene from this
group of substituted alkenes, the average percent error for the
remaining 22 chemicals ranged from +20 to -21, which ranges
from excellent to very good.
III.B.2.C.  Conjugated Dialkenes
     The experimental values of kOH at 298 K for 13 conjugated
acyclic and cyclic dialkenes are listed in Table 15 as obtained
from the literature.  For 11 compounds (excluding the compounds
3-methylene-7-methyl-l,6-octadiene and 3,7-dimethyl-l,3,6-
octatriene), kOH was estimated as follows.  Using equation 92
and the appropriate group rate constants k0,0 from Table 11 and
                            CO
C(R) =1.00 from Table 10, kad(j nar was estimated for each
conjugated diene.  These results are substituted in equation 90
to obtain kaddfnar.  For these compounds, fcjdfnar and kadd,nar
are zero.  The H-atom abstraction rate constants for the C-H
groups in each conjugated dialkene [k(l)] were obtained by the
methods described in Section III.A.  The total rate constant
k0j] for each compound is then the sum of k(l) and kadd>nar,
equation 88.
     The compounds 3-methylene-7-methyl-l,6-octadiene and 3,7-
dimethyl-l,3,6-octatriene contain one conjugated diene group
and one isolated alkene group.  Hence, for these two compounds,
                              -76-

-------
Table 15.  Comparison of Experimental and Estimated Values of
           XQU for Conjugated Acyclic and Cyclic Dialkenes at
           298 K and the Percent Error [Underlined Values of
           kOH Were Used by Atkinson (1986) to Derive the
           Substituent Factors for These Compounds]
Chemical Class/Chemical
A. ACYCLIC DIALKENES
cis-1 , 3-Pentadiene
2 -Methyl-1, 3 -butadiene
trans- 1. 3-Hexadiene
3-Methyl-l, 3-pentadiene
4 -Methyl-1, 3 -pentadiene
2 , 3-Dimethyl-l , 3-butadiene
2 , 5-Dimethyl-2 , 4-hexadiene
3-Methylene-7-methyl-l, 6-
octadiene
3 , 7-Dimethyl-l , 3 , 6-octatriene
B. CYCLIC DIALKENES
l , 3-Cyclohexadiene
1 , 3-Cycloheptadiene
a-Phellandrene
a-Terpinene
lO1^ XQJJ (cm^molecule~1s~1)
Experimental
(a)

101
101
ill
137
131
121
211
213
	

161
139
310
360
(b)

101c'e
101*
112' e
136c'e
131c'e
122c'e
210c'e
215f
252*

164d
139e
313*
363f
Estimated

105
105
106
135
135
135
231
194
223

137
139
187
235
Percent
Error1?

+4
+4
-5
-1
+3
+ 11
+10
-10
-12

-16
0
-40
-35
                          -77-

-------
a Experimental data from Atkinson (1986).
b Experimental data from Atkinson (1989).
c Experimental data from Ohta (1983).
d Experimental data from Atkinson, Aschmann, Carter (1983).
6 Experimental data from Atkinson, Aschmann, Carter (1984a).
f Experimental data from Atkinson, Aschmann, Pitts (1986).
9 Based on the experimental data given in the third column,
  Experimental/b).
* Recommended value by Atkinson (1989) with the rationale for the
  recommendation and the uncertainty for the recommendation.
                                -78-

-------
equations 92 and 91 were used to estimate k      and
                                               nar
kadd,nar, respectively, as described above while k^d/nar is
zero.  The sum of these results is fcadd,nar' equation 90.  The
H-atom abstraction rate constants for the C-H groups [k(l) ]
were obtained by the methods described in Section III. A.  The
total rate constant k0n is then equal to the sum of k(l)
and kadd,nar' equation 88.
     All the estimated values for each compound are listed in
Table 15 along with the percent error.  For the 5 compounds
below the dashed lines, the average percent error ranged from
-HO to -24 which ranged from superb to very good.  The average
percent error for the 13 compounds ranged from +5 to -17, which
is superb to excellent.  More experimental kgjj data are needed
for a number of conjugated dienes to confirm the S/R
relationships of Atkinson.
III.B.2.d.  Alkynes and 1,2-Dialkenes (Allenes)
     The experimental values of kOH at 298 K are listed in
Table 16 for five alkynes and three 1,2-dienes (allenes) as
obtained from Atkinson  (1986).  Using equation 93, the
appropriate group rate constants k,u from Table 12, and the
substituent factors C(R) = 1.00 from Table 10, kadd nar was
calculated for each compound.  For these two classes of
compounds, kadd,nar and kadd,nar are zero.  These results are
then substituted in equation 90 to obtain kadd nar*  Tne H-atom
abstraction rate constants for the C-H groups in each alkyne or
allene  [k(l) ] were obtained by the methods described in Section
                              -79-

-------
  Table 16.   Comparison of Experimental and Estimated Values of kOH
             for Alkynes and Allenes at 298 K and the Percent Error
             [Underlined Values of kQH Were Used by Atkinson (1986,
             1987)  to Derive the Substituent Factors for these
             Classes of Compounds]
Chemical Class/ Chemical
A. ALKYNES
Propyne
l-Butyne
2-Butyne
1-Pentyne
1-Hexyne
B. 1,2-DIENES (ALLENES)
1 , 2 -Butadiene
1,2-Pentadiene
3-Methyl-l, 2-butadiene
1012 k0H (cm3molecule"1s"1)
Experimental
(a)

1^1
8.0
27.4
	
	

26.0
35.6
57.1,
(b)

5.9*
8.0*
27.4*
11. 2d
12. 6d

26. le
35. 5e
56. 9e
Estimated

6.54 .
7.42
29.3
8.75
10.1

31.1
32.0
57.3
Percent
Errorf

+11
-7
+7
-22
-20
j
\
+19
-10
+1
a Experimental data from Atkinson (1986).

b Experimental data from Atkinson (1989).

c Experimental data used by Atkinson (1987) to derive the substituent
  factors for the alkynes.

d Experimental data from Boodaghians et al. (1987).

e Experimental data from Ohta (1983).

f Based on the experimental data given in the third column,
  Experimental/(b).

* Recommended value by Atkinson (1989)  with the rationale for the
  recommendation and the uncertainty for the recommendation.
                                -80-

-------
III.A.  The total rate constant kOH for each compound is then the
sum of k(l) *n
-------
Table 17.  Summary of the Average Percent Error in kOH for the
           Reaction of Hydroxyl Radicals with a Number of
           Olefins, Conjugated Diolefins, Allenes, and Alkynes
           and for All Chemicals in These Classes
Chemical Class
Unsubstituted Alkenes and
Conjugated Dienes
Substituted Alkenes and
Nonconjugated Dienes
Conjugated Dialkenes
Alkynes
1,2-Dienes (Allenes)
All compounds not used to
derive the substituent
constants and group rate
constants
All Compounds
Number of
Chemicals
39
22a
13
5
3
45
82
Average Percent
Error
From
+13
+20
+5
+9
+10
+16
+13
To
-11
-21
-17
-16
-10
-14
-15
a A total of 22 compounds were used in the estimation of kOH.
  However, 1,1-difluoroethene did not have reliable kOH data
  and was not used in the analysis of the percent error.  The
  compound ketene had a percent error greater than 100  (i.e.,
  the percent error was +200) and was not used in the analysis
  of the average percent error.
                              -82-

-------
compounds were used.  To corroborate the S/R relationships for

these two classes of chemicals, more experimental kOH data are

needed for additional compounds.


III.C.  Reaction of Hydroxyl Radicals with Organic Chemicals
        containing Sulfur, Nitrogen, and Phosphorus Functional
        Groups and the Estimation of kOH


III.C.I.  Reaction of Hydroxyl Radicals with Thiols, Sulfides,
          and Disulfides


III.C.I.a.  Formulation of the Structure/Reactivity
            Relationships

     Atkinson (1987) made a detailed study of the kinetic data

for the reaction of hydroxyl radicals with thiols, sulfides, and

disulfides.  In air at a total pressure of approximately 1

atmosphere,  and thus in the presence of oxygen, the total rate

of reaction, kOjj, is a function of H-atom abstraction by OH

radicals from the alkyl groups Ri in Ri-SH, Ri-S-Ri, and

Ri~S-S-Ri and by the interaction of OH radicals with the sulfur

functional groups to form the adduct [>S---tOH].  The adduct

reacts rapidly with oxygen in a series of complex reactions to

form the products.  Therefore, the reaction of hydroxyl radicals

with thiols  (Ri-SH), sulfides  (Ri-S-Ri), and disulfides

            can be described by the following reactions


                              OH
                              
                              
                              
             +  -OH 	  Ri-SH	  Products       (94)
                              -83-

-------
             + -OH
                              OH
Ri~s~Ri
*  Products
(95)
             + -OH
    OH
    /:
Ri-5-S-Ri
  *  Products
(96)
and by the reactions 24a, b, c for H-atom abstraction by. OH
radicals from alkyl groups R^.  In the absence of oxygen, for the
sulfides, Atkinson (1987) indicated that OH radicals only reacted
via H-atom abstraction from the alXyl groups Rj^.
     Based on a critical analysis of the kinetic data for OH
radical reaction with thiols, sulfides, and disulfides  in air at
a total pressure of approximately 1 atmosphere (and therefore in
the presence of oxygen), Atkinson indicated that the group rate
constants for these three classes of compounds were
          k(^SH) = 31 x 10~12 cm3 molecule'^-s"1

          k(-S-) = 2.0 x 1CT12 cm3molecule~1s"1
         k(-S-S-) = 200 x 10~12 cm3molecule~1s"1
                                 (97)

                                 (98)

                                 (99)
and the substituent factors were
          F(-SH) = F(-S-) = F(-S-S-) = 9.0
                                (100)
                              -84-

-------
These results are summarized in Tables 1 and 2, respectively, for
the group rate constants and the substituent factors for these
sulfur functional groups.
     Using equation 20, the overall rate of OH radical reaction
with thiols, sulfides, and disulfides in air at a total pressure
of approximately 1 atmosphere, and thus in the presence of
oxygen, is given by the relationship
                   COH
k(4)                     .  (101)
where:  k(l) is the contribution to kOH from H-atom abstraction
from an alkyl group R^  (equation 12):  and k(4) represents the
contribution to k0n from the interaction of OH radicals with the
sulfur functional groups (equation 15) , which is the group rate
constant for these sulfur compounds.
     For sulfides, in the absence of oxygen, k(4) = 0 so that
equation 101 becomes
                        kOH = k(l)                       (102)

and only H-atom abstraction from the alkyl groups in R^  is
observed.  The group rate constant k(-S-) = 0, in the absence of
oxygen, is listed  in Table 1.

Ill.C.l.b.  Estimation of kOH at 298 K and a Comparison  of
            These  Results with the Experimental Data
     The experimental values of kOH at 298 K in air at a pressure
of approximately 1 atmosphere  (and therefore in the presence of
oxygen) are listed in Table 18 for nine thiols and
                              -85-

-------
Table 18.  Comparison of Experimental and Estimated Values of
           kOH for Alkyl Thiols, Sulfides, and Disulfides at
           298 K and the Percent Error [Underlined Values of
           kop Were Used by Atkinson (1987)  to Derive the
           Substituent Factors for These Classes of Compounds]
Chemical Class/Chemical


A. THIOLS
Methanethiol
Ethanethiol
l-Propanethiol
2 -Propanethiol
1-Butanethiol
2-Methyl-l-propanethiol
2-Butanethiol
2-Methyl-2-propanethiol
2 -Methy 1-1-butanethiol
B.I. ACYCLIC SULFIDES0
Dimethyl sulfide
Methyl ethyl sulfide
Diethyl sulfide
Di-n-Propyl Sulfide
1012 koH |
Exoerii
(a)

33.1
46.5
45.9
42.4
43.8
41.8
39.8
35.1
51n

4.28
JLJi
15.5
	
[cm3molec
lent a 1
(b)

32.9*
46.8*
48.3*
42.0*
51*
45*
40*
33.1*
54.3d

4.56*
8.50e
15*
20. Of
:ule~1s~1)
Estimated


32.3
38.7
42.0
47.8
43.4
43.5
53.7
31.6
44.9

2.59
9.02
15.5
22.0
Percent
Error^


-2
-17
-13
+14
-15
-3
+34 '
-5
-17

-43
+6
+3
+ 10
                              -86-

-------
Table 18.  Continued
Chemical Class/Chemical
B.2. CYCLIC SULFIDES0
Tetrahydrothiophene
C. DISULFIDES
Dimethyl disulfide
1012 kOH (cm3molecule"1s"1)
Exoerimental
(a)

19.1

205
(b)

19.7*

211*
Estimated

17.8

203
Percent
Error9

-10

-4
a Data were obtained from Table VII of the paper by Atkinson
  (1987) .  It should be noted that the second column of Table VII
  represents the estimated value of kOH while the third column
  represents the experimental value.

b Experimental data from Atkinson (1989) .
c For these compounds,
                           was measured in tne absence of oxygen.
d Experimental data from Barnes et al.  (1986).

e Experimental data from Hynes et al.  (1986) .

f Experimental data from Barnes et al.  (1986).  The experimental data
  of Nielsen et al. (1987) appear to be erroneous  [Atkinson  (1989)].

9 Based on the experimental data given  in the third column,
  Experimental/ (b) .

n In Table VIII of the paper by Atkinson  (1987), the molecular structure
  of the compound corresponding to this value of kOH was
  CH3CH(CH3)CH2CH2SH  (3-methyl-l-butanethiol) as obtained from Barnes et
  al.  (1986).  However, from the paper  by Barnes et al.  (1986), the
  compound was 2-methyl-l-butanethiol.  This has been corrected in the
  book by Atkinson  (1989).

* Recommended value by Atkinson  (1989)  with the rationale for the
  recommendation and  the uncertainty for the recommendation.
                                -87-

-------
one disulfide as obtained from the literature.4  For the five
sulfides, the experimental values of kOH, measured in the
absence of oxygen, were obtained from the literature.4
     For the estimation of kOH for the five sulfides, in the
absence of oxygen, equation 102 is applicable.  Thus, only
H-atom abstraction from the alkyl groups R^ is needed.  Using
equation 28 for H-atom abstraction and the appropriate group
rate constants and substituent factors from Tables 1 and 2,
respectively, kOH was estimated for the four acyclic sulfides
and these results are listed in Table 18.  For tetrahydrothio-
phene, which is a cyclic sulfide, equation 43 is valid; and
using the appropriate group rate constants and substituent
factors, kOH was estimated in the standard manner for this
cyclic compound.  This result is listed in Table 18.  In
addition, the percent error in kOH for each sulfide is also
listed in this table.  The average percent error for the five
sulfides ranged from +6 to -27 so that these results ranged
from superb to very good.  Only the rate constants kOH for di~
n-propyl sulfide and tetrahydrothiophene were not used to
derive the substituent factors for the sulfides.  The percent
errors for these two compounds were +10 and -10, respectively,
tentatively confirming the S/R relationships.  However, more
experimental k^jj data is needed for additional alkyl sulfides
(both cyclic and acyclic) to confirm these S/R relationships.
4 Data were obtained from Table VII of the paper by Atkinson
  (1987).  It should be noted that the second column in Table vn
  represents the estimated value of k0jj while the third column
  represents the experimental value of kOH.
                              -88-

-------
     For the estimation of kOH in the presence of oxygen for
the nine thiols, equation 101 is applicable.  Using the
appropriate group rate constants and substituent factors for
the alkyl groups from Tables 1 and 2, respectively, k(l) was
estimated for each chemical using equation 28.  The group rate
constant for the thiols [k(-SH)] was obtained from Table 1.
The sum of k(l) and k(4) is equal to kOH and these results are
listed in Table 18 along with the corresponding percent error.
The average percent error for these 9 thiols ranged from +24 to
-10 so that these results ranged from very good to superb.  All
nine compounds were used to derive the group rate constants and
substituent factors for the thiols.  Hence, more experimental
kOH data is needed for additional alkyl thiols to confirm these
S/R relationships.
    In a similar manner as described above, k0H was estimated
for one disulfide along with the percent error.  These results
are listed in Table 18.  The percent error for dimethyl
disulfide is -4, which is superb; however, more experimental
k-., data are needed for additional alkyl disulfides to confirm
 un
the S/R relationships of Atkinson for this class of compounds.

III.C.2.  Reaction of Hydroxyl Radicals with Aliphatic Amines,
          Hydrazines, N-Nitrosamines, N-Hydroxylamines, and
          N-Nitramines

III.C.2.a.  Formulation of the Structure/Reactivity
            Relationships
     Atkinson  (1987) indicated that  in air at a total pressure
of approximately one atmosphere, OH  radicals can react with
aliphatic amines via H-atom abstraction from the alkyl group
                              -89-

-------
and by OH radical interaction with the nitrogen atom in an
analogous manner to those described for the thiols, sulfides,
and disulfides.  Therefore, OH radicals can interact with the
nitrogen in the amines to form the adduct
                            H
                       Ri N  OH                      (103)
                            H

which then decomposes rapidly in the presence of oxygen to form
the products.  Thus, the reaction of OH radicals with primary
aliphatic amines can be described by the reaction
 Ri-NH2 + 'OH
                         H
                                       2
N -OH
                         H
*  Products     (104)
while H-atom abstraction from the alkyl group R^ is given by
reactions 24a,b,c.  Similar reactions can be written for
secondary amines  (R^)2NH and tertiary amines (R^)3N.
     From equation 20, OH radical reaction with amines can be
described by the relationship
                               + k(5)                     (105)

where k(l) represents the contribution to kOH from H-atom
abstraction from the alkyl group R^ while k(5)  represents the
contribution to JCQH from OH radical interaction with the
nitrogen atom in the amine group.
                              -90-

-------
      Based on a critical  analysis of the kOH data for the
 amines  including diethyl-N-hydroxylamine,  Atkinson (1987) found
 that  for this class of chemicals the group rate constants were

           k(-NH2)  = 20 x  10~12  cm3molecule"1s"1           (106)

         k(>NH)  = k(>N-) = 60 x  10~12 cm3molecule""1s"1     (107)

 and the substituent factors were

                F(-NH2) =  F(>NH)  = F(>N-) = 10             (108)

 These results are summarized in Tables 1 and 2.
      For hydrazine (H2N-NH2) and alkyl substituted hydrazines
 (Ri~NH-NH2, RiNH-NHRi, etc.)/ the reaction pathways for the
.reaction of OH radicals are similar to those described above
 for the amines.  Thus, OH radicals can react with the nitrogen
 functional groups similar to reaction 104 and can abstract a
 hydrogen atom from the alkyl group R^ similar to those
 described in reactions 24a,b,c.   For hydrazine, Atkinson (1987)
 assumed that the neighboring -NH2 group had essentially no
 effect  on the OH radical interaction group rate constant so
 that

                   koH = 2k(-NH2)                          (109)

 and the substituent factor F(X)  for -NH2 bonded to another -NH2
 group was equal to 1.0.  From the very limited k-.. data from
                                                 vJn
 the alkyl substituted hydrazines, Atkinson found that the group
 rate constants and substituent  factors listed in 106, 107, and
 108 were applicable.
                              -91-

-------
     In exactly the same manner as described above, and on the
very limited kinetic data for N-nitrosamines and N-nitroamines,
Atkinson (1987) indicated that the group rate constants for
these compounds were

               k(>NNO) = k(>NN02) = 0                     (110)

and the substituent factors F(X) were

                         F(>NNO) = F(>NN02)             .  (Ill)

     Although Atkinson (1987) did not explicitly define group
rate constants and substituent factors for the N-substituted
hydroxy lamines , from the experimental k0n data in Table 19B,

                          k(>NOH) = 0                     (Ilia)

                    F(-NHOH) = F(>NOH)  0
The group rate constants from equations 110 and Ilia are listed
in Table 1 while the substituent factors from equations 111 and
lllb are listed in Table 2.

III.C.2.b.  Estimation of kpH at 298 K and the Comparison of
            these Results with Experimental Data
     The experimental values of kOH for six amines, one each
for N-hydroxylamine, N-nitrosamine, N-nitramine, and for two
hydrazines at 298 K and in air at a total pressure of
approximately 1 atmosphere are listed in Table 19 as obtained
from the literature.  Using equations 28 and 105 and the
appropriate group rate constants and substituent factors for
these compounds from Tables 1 and 2, kOH was estimated for the
                              -92-

-------
Table 19.  Comparison of Experimental and Estimated Values of
           kgH at 298 K for Alkyl Amines, Hydrazines, and
           N-substituted Amines and the Percent Error [Underlined
           Values of kOH Were Used by Atkinson (1987) to Derive the
           Group Rate Constants and Substituent Constants for
           These Compounds]
Chemical Class/Chemical
A. AMINES
Methylamine
Ethylamine
Dimethylamine
Trimethylamine
D imethy Ihydr oxy ethy 1 amine
2-Methyl-2-amino-l-propanol
B. N-HYDROXYLAMINES
Diethyl-N-hydroxylamine
C. N-NITROSAMINES
Dimethyl-N-nitrosamine
D. N-NITRAMINES
D imethy 1-N-nitr amine
E. HYDRAZINES
Hydrazine
Me thy Ihydr a z ine
1012 kOn (cm3molecule~1s~1)
Experimental
(a)

22.0
27.7
65.4
60.9
80
28

101

2.53

3.84

61
65
(b)

22.0
27. 7d
65. 4d
60. 9d
90e
28f

1019

2.53h

3.84h

611
651
Estimated

21.4
28.6
62.9
64.3
77.4
24.1

77.2

2.88

2.88

40.0
81.4
Percent
ErrorJ

-3
+ 3
-4
+6
-14
-14

-24

+ 14

-25

-34
*25
                              -93-

-------
Table 19.  Continued

a Experimental data from Table VII of the paper by Atkinson  (1987).
  It should be noted that the second column in Table VII represents
  the estimated value of kOH while the third column represents the
  experimental value.
b Experimental data from Atkinson (1989) and the literature.
c Experimental data from Atkinson, Perry, Pitts (1977).
d Experimental data from Atkinson, Perry, Pitts (1978).
e Original experimental data is from Anderson and Stephens  (1988) which
  represents the most reliable data [Atkinson (1989)].
f Experimental data from Harris and Pitts (1983).
9 Experimental data from Gorse et al. (1977).
11 Experimental data from Tuazon et al.  (1984).
1 Experimental data from Harris et al.  (1979) as reported by Atkinson
 (1987).
J Based on the experimental data given in the third column
  Experimental/(b).
* Recommended value by Atkinson (1989) with the rationale for the
  recommendation and the uncertainty in the recommendation.
                                -94-

-------
amines in the standard manner.  These results are summarized in
Table 19 along with the percent error.  For the six amines, the
average percent error ranged from +5 to -9 indicating that the
S/R relationships of Atkinson for the aliphatic amines are
superb.  However, considerably more experimental kOH data are
needed for additional alkyl amines to confirm the S/R
relationships of Atkinson.
     The total rate constant k0n fr diethyl-N-hydroxylamine,
dimethyl-N-nitrosamine, dimethyl-N-nitroamine, hydrazine, and
methyl hydrazine was estimated in the standard manner as
described above and these results are listed in Table 19 along
with the percent error.  The percent errors for these compounds
ranged from excellent to very good.  However, considerably more
experimental kOH data are needed for chemicals in these classes
of compounds to confirm the S/R relationships of Atkinson.

III.C.3.  Reaction of Hydroxyl Radicals with Organophosphorus
          Compounds

III.C.3.a.  Formulation of the Structure/Reactivity
            Relationships
     Atkinson made a detailed study of the kinetic data for the
reaction of hydroxyl radicals with several classes of
organophosphorus compounds [Atkinson  (1988); Atkinson et al.
(1987b, 1988a); Atkinson in Goodman et al. (1988, 1988a); and
in Tuazon et al. (1986)].  For compounds with molecular
structure
                              -95-

-------
                                                          (112)
where X is 0, or X = 0 and S, and R^ is an alkyl group,
hydroxyl radicals can react with them via two pathways.  One
pathway involves the formation of a phosphorous complex with OH
radicals followed by rapid decomposition to products in the
presence of oxygen
( P=X  + -OH
p=:x
r \
  bH
                                               Products   (113)
The second pathway involves H-atom abstraction from the alkyl
groups  (reactions 24a,b,c).  Similar reaction pathways can be
written for dialkyl chlorophosphorothioates.  In addition,
similar reaction pathways can be written for the classes of
compounds with molecular structure
                        X
                        II
                        PXR2
                        NR3R4
                                                          (114)
where X = O, or X = O and S, P.1 and R2 are alkyl groups, and R3
and R4 are H and/or alkyl.  Furthermore, OH radicals can react
with the functional group NR3R4 as described in Section
III.C.2.
                              -96-

-------
     From equation 20, OH radical reaction with the phosphorus
compounds given by molecular structure 112 can be described by
the following relationship
                   kOH - k(l) + k(6)                     (115)

where k(l) represents the contribution to kOH from H-atora
abstraction from the alkyl groups and k(6) represents the
contribution to kOH from the OH radical interaction with the
phosphorus groups.
     For the phosphorus compounds given by molecular structure
114, OH radical reaction can be described by the following
relationship
                  kOH = k(l) + k(5) + k(6)                (lie)

where k(l) represents the contribution to k_ from H-atom
                                           un
abstraction from the alkyl group R^, k(5) represents the
contribution to kOH from OH radical interaction with the
nitrogen group, while k(6) represents OH radical interaction
with the phosphorus group.
     Atkinson  [Atkinson (1988); Atkinson et al. (1988);
Atkinson in Goodman et al.  (1988,  1988a) ; and Atkinson in
Tuazon et al.  (1986)] analyzed the kinetic data for these
organophosphorus compounds in the  standard manner and found
that the group rate constants were

                  k[P(0)] = 0                              (117)

            k[PCl in  (CH30)2P(S)C1] = 0                    (118)

                              -97-

-------
         k[P(S)] = 55 x 10-12 cn^molecule-is-1             (119)

         k(-S-) = 2.0 x 10~12 cm3molecule~1s~1             (120)

and the substituent factors were

           F(-0-P<) = F(-S-P<) = 20                        (121)

                   F(-S-) - 9.0                            (122)

These data are listed in Tables 1 and 2.  For those organophos-
phorus compounds containing nitrogen functional groups, the
group rate constants and substituent factors defined in
equations 106, 107, and 108 are applicable.

III.C.3.b.  Estimation of kpH at 298 K and the Comparison of
            These Results with Experimental Data
     The experimental kOH data in the second column of Table 20
were taken from the literature as follows: the experimental KQ^
data for trimethyl phosphate was taken from Atkinson (1988) and
Atkinson in Tuazon et al. (1986); triethyl phosphate from
Atkinson et al. (1988) and from Atkinson  (1988).  The
experimental kOn data for the next four alkyl thiophosphates
were taken from Atkinson in Goodman et al. (1988) and Atkinson
(1988).  Similarly, the experimental kOH data for one chloro-
phosphorothioate was obtained from Atkinson et al. (1988); and
the experimental kOH for the three alkyl phosphoroamidothioates
and the single alkyl phosphoroamidate were obtained from
Goodman et al.  (1988a).  The best available kOH data for these
compounds are  listed in the third column, Experimental/(g), as
                              -98-

-------
Table 20.  Comparison of Experimental and Estimated Values of
           KQH at 298 K for Aliphatic Compounds Containing
           Phosphorus Functional Groups and the Percent Error
Chemical Class/Chemical
A. ALKYL PHOSPHATES/
THIOPHOSPHATES
Trimethyl phosphate
(CH30)3P=0
Tri ethyl phosphate
(CH3CH20)3P=O
0,0,0-Tr imethyl
phosphorothioate
(CH30)3P=S
o,0, S-Tr imethyl
phosphorodithioate
(CH30)2P(S)SCH3
0,0, S-Tr imethyl
phosphorothioate
(CH30)2P(0)SCH3
0 , S , S-Tr imethyl
phosphor od ith ioat e
(CH3S)2P(0)OCH3
B. DIALKYL CHLORO-
PHOSPHOROTHIOATES
0,0-Dimethyl chloro-
phosphorothioate
(CH30)2P(S)C1
1012 k0n (cm3molecule"1s~1)
Experimental

7.4a
55. 3b
69.7
56.0
9.15
9.45
59. 6b
(g)
7.37
55.3
69.7
56.0
9.29
9.59
59.0
Estimated
8.64
52.2
63.6
65.6
10.6
12.6
60.8
Percent
Errorf
-1-17
-6
-9
+ 17
+ 14
+31
+3
                              -99-

-------
Table 20.  Continued
Chemical Class/Chemical
C. ALKYL PHOSPHOROAMIDATES
AND ALKYL PHOSPHOROTHIO-
AMIDATES
0,O-Dimethyl
phosphoroamidothioate
(CH30)2P(S)NH2
0,0,N-Trimethyl
phosphoroamidothioate
(CH30)2P(S)NHCH3
0 , 0 , N , N-Tetramethy 1
phosphoroamidothioate
(CH30)2P(S)N(CH3)2
0 , O , N , N-Tetramethy 1
phosphoroamidate
(CH30)2P(0)N(CH3)2
1012 kOH (cm3molecule~1s~1)
Experiment a 1

244d
232d
46. 8d
31. 9d
(g)
244
233e
46.8
31.9
Estimated
80.8
122
124
68.6
Percent
Errorf
-67
-48
+160
+ 115
a Experimental data from Atkinson in Tuazon et al.  (1986) and Atkinson
  (1988) .
b Experimental data from Atkinson et al. (1988) and Atkinson (1988).
c Experimental data from Atkinson in Goodman et al. (1988) and Atkinson
  (1988).
d Experimental data from Atkinson in Goodman et al. (1988a).
e Average value of kOH using the reference compounds propene and
  2,3-dimethyl-2-butene from Goodman et al. (1988a).
f Based on the experimental kOH data given in the third column,
  Experimental/(b).
9 Best available data from Atkinson  (1989).  It should be noted that
  these data are not recommended by Atkinson (1989) since the
  experimental data for each compound is only from one source.
                               -100-

-------
obtained from Atkinson (1989).   It should be noted that these
data are not recommended by Atkinson (1989) since the
experimental data for each compound was obtained from a single
source.
     Using equations 20, 28, 115, or 116 and the appropriate
group rate constants and substituent factors from Tables 1 and
2, kOH was estimated for six phosphates/thiophosphates, one
chlorophosphorothioate and four alkyl phosphoroamidates/
phosphorothioamidates.  These values of kOH are listed in
Table 20 along with the percent error.
     For the six phosphates and thiophosphates, the average
error ranged from +20 to -8 indicating that the S/R
relationships developed by Atkinson ranged from excellent to
superb.  The single chlorophosphorothioate had an estimated
value of kOH =* 60.8 x 10~12 cm3molecule~1s~1 with a percent
error of +3 which is superb.  These results are expected since
Atkinson (1987) used all the kOH data for the compounds listed
in Table 20.A. and B. to derive the group rate constants and
substituent factors for these compounds.  Therefore, kOH data
for several more compounds in these classes of compounds must
be obtained to confirm the S/R relationships of Atkinson.
     Inspection of the kOH data for four alkyl phosphoroami-
dates /phosphorothioamidates  indicates that two of the compounds
had percent errors greater than +100.  Therefore, neglecting
these two compounds, the average percent error is -58 which is
relatively poor.  It appears that for these compounds, which
contain both nitrogen and phosphorus functional groups, OH
                             -101-

-------
radical interaction is more complex.  Therefore, more experi-
mental KQH data are needed on a number of compounds in these
two classes of chemicals to evaluate and refine the S/R
relationships of Atkinson.

III.C.4.  Summary
     Table 21 summarizes the average percent error in kOH for
the reaction of OH radicals with organosulfur, organonitrogen,
and organophosphorus compounds.  The second-order rate constant
KOH was estimated for a total of 37 compounds, Tables 18-20,
and these results are compared to the experimental values.
Only two of these compounds had a percent error greater than
+100 [(CH30)2P(S)N(CH3)2  (+160); (CH3O)2P(O)N(CH3)2 (+115)] and
the results for these two compounds were omitted in the
analysis.  For the remaining 35 compounds, the average percent
error ranged from +14 to -18 which is excellent.  Only two
compounds were not used in the derivation of the group rate
constants and substituent factors for these classes of
compounds.  These were:  di-n-propyl sulfide (+10 percent
error) and tetrahydrothiophene (-10 percent error).  These
results were superb, tentatively confirming the S/R
relationships for the sulfides.  However, very limited data
were available for most of these classes of compounds so that
considerably more experimental kOH data are needed for these
classes to confirm some of the S/R relationships of Atkinson.
                             -102-

-------
Table 21.  Summary of the Average Percent Error in kOH at 298 K
           for the Reaction of Hydroxyl Radicals with a Number of
           Chemicals in Several Classes of Chemicals Containing
           Sulfur, Nitrogen, and Phosphorus Functional Groups and
           for All Chemicals in These Classes of Chemicals
Chemical Class
A. SULFUR COMPOUNDS
Thiols
Sulfides
Disulfides
B. NITROGEN COMPOUNDS
Alkyl amines
Alkyl N-hydroxylamines
Alkyl N-nitrosamines
Alkyl N-nitramines
Alkyl hydrazines
C. PHOSPHORUS COMPOUNDS
Alkylphosphates/
thiophosphates
Dialkylchlorophos-
phorothioates
Alky Iphosphoroamidates /
phosphorothioamidatesa
Chemicals not used to
derive the substituent
constants and rate
constants
ALL COMPOUNDS
Number of
Chemicals

9
5
1

6
1
1
1
2

6
1
2
2
35
Average Percent
Error
From

+24
+6


+5

+14

+25

+20
+3

+10
+14
To

-10
-27
-4

-9
-24
--
-25
-34

-8
--
-53
-10
- 1 3
                             -103-

-------
Table 21.  Continued
  Estimates of kOH were made for four compounds in these two
  classes of compounds.  Two of the chemicals had percentage errors
  greater than +100 [(CH3O)2P(S)N(CH3)2(+160); (CH3O)2P(0)N(CH3)2
  (+115)].  These two results were excluded in estimating the
  average percent error for all chemicals in these classes.
                             -104-

-------
III.D.  Reaction of Hydroxyl Radicals with Aromatic Compounds
        and the Estimation of kOH

III.D.I.  Formulation of the Structure/Reactivity Relationships
     Atkinson (1986, 1987, 1987a,b, 1988, 1988a) made a
detailed study of the kinetic data for the reaction of hydroxyl
radicals with aromatic compounds.  This reaction involves the
addition of OH radicals to the aromatic ring and the reaction
of OH radicals with the substituents on the aromatic ring.  For
example, for toluene in air at a total pressure of
approximately one atmosphere at a constant temperature, OH
radicals add to the aromatic ring and abstract a hydrogen from
the CH3 substituent on the ring.  Thus, the reaction of toluene
with OH radicals can be described by the following two reaction
pathways
                    OH
+  HOH
(123)
                    OH
-1-  HOH
(124)
     Atkinson indicated that the rate constant for the
addition of OH radicals to an aromatic ring, k(7) [from
equation 18], is a function of the sum of the electrophilic
                             -105-

-------
substituent constants, J^ of Brown and Okamoto  (1958) .
Based on a least-squares correlation of the room-temperature
rate constants for OH addition to the aromatic ring  [kadd ar]
with the ff+ values for 34 aromatic compounds (i.e., those
compounds whose names are marked with the superscript ** in the
first column in Table 23), Atkinson (1987) found that

        Io9io[*add,ar] = -H-69 - 1-35 a+               (125)
For convenience, the rate constant for the addition  of OH
radicals to an aromatic ring is expressed as 1012kadd ar as
shown in Table 23 and in all calculations.  Thus, equation 125
has been modified by adding +12 to both sides of this equation.
As a result, one obtains
         Iog10[l012kadd/ar] = 0.31 - 1.35 
-------
of a+ for the ortho position will be discussed in the next
paragraph.  The substituents are listed in Table 22 in the
order of increasing value of a+.  The values of a"*" and a~j" were
obtained from Brown and Okamota (1958) for a large number of
substituents.  In addition, the a+ values for a number of
additional substituents were obtained from Meylan (1990).
Meylan derived these a+ values by analogy with similar
structures.  Leifer also derived the a+ values for a few
substituents by analogy with similar structures.  The values of
aj" and a+ for the polychlorobiphenyl ring [i.e., -C6H4C1,
-C6H3Cl2, -C6H2C13, -C6HC14, and -C6C15] were originally
calculated by Atkinson (1987a) and were revised slightly
[Atkinson  (1987)].  The revised values are listed in Table 22.
     The values of ]Pff+ for various substituents on the
aromatic ring can be calculated using the following rules:

     (1)  steric hindrance is neglected;
     (2)  aj = a ;
     (3)  ^ a+ represents the sum of all the substituent
          constants on the aromatic ring;
     (4)  the hydroxyl radical adds to the position with the
          most negative value of   a+ (preferably a free
          position); and
                             -107-

-------
Table 22.  Electrophilic  Substituent  Constants (a* and a"1")
           for a Number of  Substituents           m      P
Substituent
Dimethylamino
Dialkylamino
(assume dimethyl
amino)
Anilino
Sulfoxide
Amino
Secondary Amine
Hydroxy
Methoxy
H-Alkoxy (assume
methoxy)
Oxide (assume
methoxy)
Thiol (assume
methylthio)
Methylthio
n-Alkylthio (assume
methylthio)
Sulfide (assume
methylthio)
Disulfide (assume
methylthio)
Acetylamino
Benzoylamino
Structure
-N(CH3)2
-N(R)3
-NHC6H5
-S(0)-
-NH2
-NH-
-OH
-OCH3
-OR
-0-
-SH-
-SCH3
-SR
-S-
-S-S-
-NHC(0)CH3
-NHC(0)C6H5
<<>a
-0.16b
-0.16
-0.16b
-0.16b
-0.16
-0.16b
0.121b
0.047
0.047b
0.047b
0.158b
0.158
0.158
0.158b
0.158
0.21b
0.21b
#a
-1.7
-1.7C
-1.3
-1.3b
-1.3
-1.0b
-0.92
-0.778
-0.778b
-0.778b
-0.604b
-0.604
-0.604C
-0.604b
-0.604
-0.6 \
-0.6
                              -108-

-------
Table 22.  Continued
Substituent
Phenoxy
Ethenoxy (assume
phenoxy)
Methyl
Ethyl
n-Alkyl
Methylene (assume
ethyl)
Hydr oxymethy 1
(assume ethyl)
i-Propyl
Methine (assume
i-propyl)
t-Butyl
Oxyphosphorous
Phenyl
Carboethoxymethyl
0-Naphthyl
Aromatic (other
than phenyl)
Hypohalous (e.g.,
hypochlorous)
Car boxy lie Ester
(aliphatic)
Structure
-OC6H5
-OCH=CH2
-CH3
-CH2CH3
-R
-CH2-
-CH2OH
-CH(CH3)2
>CH-
-C(CH3)3
-O-P
-C6H5
-CH2C(0)OCH2CH3
-C10H7(/3)
-Aromatic
-OX
-OC(0)R
;)
0.10b
0.10
-0.066
-0.064
-0.064C
-0.064b
-0.064
-0.060
-0.060b
-0.059
0.10b
0.109
-0.10
0.10C
0.10
0.15b
0.10b
(^)a
-0.5
-0.5C
-0.311
-0.295
-0.295
-0.295b
-0.295
-0.280
-0.280b
-0.256
-0.20b
-0.179
-0.164
-0.135
-0.135
-0.10b
-0.10b
                            -109-

-------
Table 22.  Continued
Substituent
Car boxy lie Ester
(aromatic)
Fluoro
Fluoromethyl
Carboxylate
Chloromethyl
Bromomethyl
(assume
Chloromethyl)
lodomethyl
(assume
Chloromethyl )
Ha lome thine
( assume
Chloromethyl)
Hydrogen
Undefined
Phosphoro
Cyanomethyl
Olefinic
Chlorophenyl
Trimethylsilyl
Structure
-OC(0)C6H5
-F
-CH2F
-C(0)0e
-CH2C1
-CH2Br
-CH2I
-CH-Halogen
-H
	
-P
-CH2CN
-C=C-
-C6H4C1
-Si(CH3)3
<*m>a
0.10b
0.352
0.10b
-0.028
0.14
0.14b
0.14b
0.14b
0.000
Ob,c
0.0b
0.17
0.02b
0.25d
0.011
)*
-0.10b
-0.073
-0.05b
-0.023
-0.01
-0.01b
-0.01b
-0.01b
0.000
Ob,c
0.0b
0.01b
0.02b
0.02d
0.021
                           -110-

-------
Table 22.  Continued
Substituent
Chloro
lodo
Bromo
Sulfocarbonyl
Imino
Aldehyde
D i ch 1 or opheny 1
Acetylenic
Thiocyanate
Car bony 1
Tr ime t hy 1 ammon ium
Tr ia Iky lammonium
Triaryl ammonium
Trichlorophenyl
Carboxy
Carboethoxy
Carboalkoxy
Carbomethoxy
Sulfonic Acid
Esters
Trifluoromethyl
Tetrachlorophenyl
Azo
Structure
-Cl
-I
-Br
-SC(0)-
-N=
-CH(0)
-C6H3C12
-C3C-
-SCN
-C(0)-

-N(CH3)3
-N(R)3
-N(Ar)3
-C6H2C13
-C(0)OH
-C(0)OCH2CH3
-C(0)OR
-C(0)OCH3
-S(0) (0)OR
-CF3
-C6HC14
-N=N-
<:>a
0.399
0.359
0.405
0.20b
-0.03b
0.36b
0.39d
0.21b
0.30b
0.10b
0.359
0.359
0.359C
0.53d
0.322
0.366
0.366
0.368
0.50b
0.52
0.67d
0.30b
<>a
0.114
0.135
0.150
0.15b
0.15b
0.22b
0.22d
0.23b
0.25b
0.35b
0.408
0.408
0.408
0.42d
0.421
0.481
0.481
0.489
0.50b
0.612
0.62d
0.64b
                           -111-

-------
  Table 22.  Continued
Substituent
Trichloromethyl
(similar to -CF3)
Tribromomethyl
(similar to -CF3)
Tr i i odome thy 1
(similar to-CF3)
Cyano
Nitro
Nitrate
(assume nitro)
Pentachlorophenyl
Structure
-CC13
-CBr3
-CI3
-CN
-N02
-ONO2
-c6ci5
(<>*
0.55b
0.55b
0.55b
0.562
0.674
0.674b
0.81d
#a
0.65b
0.65b
0.65b
0.659
0.790
0.790b
0.82d
a Data from Brown and Okamota (1958).
b Data from Meylan (1990) based on similar structures.
c Data from Leifer (1990) based on similar structures.
d Data from Atkinson (1987).
                             -112-

-------
      (5)   if all the positions on the ring are occupied, the
            ipso position (i.e., the position on the ring
            being evaluated) is treated as the meta position.
            This rule will become clearer when a specific
            example will be used to illustrate the method for
            estimating kadd,ar    See Section IV. P. 7.
            Hexaf luorobenzene .

III.D.2.  Estimation of )CQH for Several Classes of Aromatic
          Compounds at 298 K and the Comparison of These.
          Results with the Experimental Data
      Table 23 lists the pertinent kOH data at 298 K for a
number of aromatic compounds as obtained from the literature.
This table is in a similar format to Table 3. A. and, in
addition, contains the column a+ for each compound.  As
mentioned in Section III. D.I, the chemicals with the
superscript ** after the name were used by Atkinson (1987) to
derive equation 125.  The chemicals below the dashed line in
Table 23 were not used by Atkinson to derive equation 125.

III.D.2. a.  Benzene and Biphenyl
     The recommended experimental value of k_.u for benzene is
                                            
-------
Table 23.  Comparison of Experimental and Estimated Values of kOH for
           Chemicals in Various Classes of Aromatic Chemicals at 298 K
           and the Percent Error [The Chemicals Whose Names are Marked
           with a Superscript ** Were Used by Atkinson (1987) to
           Derive Equation 125]
Chemical Class/Chemical
A. UNSUBSTITUTED AROMATIC
COMPOUNDS
Benzene**
Biphenyl**
B. ALKYLBENZENES
Methylbenzene (Toluene) **
Ethylbenzene**
n-Propylbenzene**
i-Propylbenzene**
o-Xylene**
m-Xylene**
g-Xylene**
o-Ethyltoluene**
m-Ethyltoluene**
j>-Ethyltoluene**
1,2, 3-Trimethylbenzene**
1,2, 4-Trimethylbenzene**
1,3, 5-Trimethylbenzene**
-Buty Ibenzene
E+

0.000
-0.179

-0.311
-0.295
-0.295
-0.280
-0.377
-0.622
-0.377
-0.375
-0.606
-0.375
-0.688
-0.688
-0.933
-0.256
10 KOH (cm3molecule~1s~1)
Experimental
(a)

1.28
7.5c'd

6.19
7.5
5.7
6.6
14.7
24.5
15.2
12.0
17.1
11.4
33.3
40.0
62.4
	
(b)

1.23*
7.2*

5.96*
7.1*
6.0*
6.5*
13.7*
23.6*
14.3*
12.3*
19.2*
12.1*
32.7*
32.5*
57.5*
4.60d
Estimated

2.04
7.12

5.51
6.13
7.46
7.08
6.88
14.4
6.88
7.72
14.6
7.72
17.8
17.8
37.5
5.08
Percent
Errorcc

+66
-1

-8
-14
+24
+9
-50
-39
-52
-37
-24
-36
-46
-45
-35
+ 10
                                  -114-

-------
Table 23.  Continued
Polemical Class/Chemical
C. ALKENYLBENZENES
Phenylethene (Styrene)
2-Phenyl-l-propene
(o-Methylstyrene)
trans- 1 -Pheny 1-1 -pr opene
(/3-Methylstyrene)
l-Phenyl-2-methyl-l-propene
(j3-Dimethylstyrene)
D . HALOBENZENES
Fluorobenzene**
Chlorobenzene**
Bomobenzene* *
lodobenzene**
o-Dichlorobenzene**
in-Dichlorobenzene**
g-Dichlorobenzene**
1,2, 4-Trichlorobenzene**
Hexaf luorobenzene* *
n-Propylpentafluorobenzene
E. HALOALKYLBENZENES
Benzotrifluoride**
*

0.02
0.02
0.02
0.02

-0.073
0.114
0.150
0.135
0.513
0.228
0.513
0.627
0.837
0.421

0.520
10 kOH (cm3molecule~1s~1)
Experimental
(a)

52
52
59
32

0.54
0.94
0.71
0.93
0.42
0.72
0.32
0.532
0.219
3.06

0.48
(b)

58*
52*
59*
339

0.69*
0.77*
0.77*
1.1*
0.42n
0.72h
0.32h
0.5321
0.172*
3.06J

0.46k
Estimated

28. 2e
53. 5e
65. 7e.
89. le

2.56
1.42
1.28
1.34
0.414
1.01
0.414
0.291
0.151
2.90

0.406
Percent
Errorcc

-51
+3
+11
+170

+270
+84
+66
+22
-1
+40
+29
-45
-12
-5

-12
                                  -115-

-------
Table 23.  Continued
Chemical Class/ Chemical
4-Chlorobenzotrifluoride**
Benzyl chloride
F. MONOCHLOROBIPHENYLS
2 -Chlorobipheny 1
3 -Chlorobipheny 1
4 -Chlorobipheny 1
G. HYDROXYBENZENES
Phenol**
o-Cresol**
m-Cresol**
g-Cresol**
2 , 3-Dimethylphenol
2 , 4-Dimethylphenol
2 , 5-Dimethylphenol
2 , 6-Dimethylphenol
r.
0.634
-0.010

Ring A:
0.021
Ring B:
0.2201
Ring A:
0.021
Ring B:
-0.0651
Ring A:
0.021
Ring B:
0.2201

-0.920
-0.986
-1.231
-0.986
-1.297
-1.052
-1.297
-1.052
10 kOH (cm3molecule"1s~1)
Experimental
(a)
0.25
2.9

2.9
5.4C
3.9C

28.3
40
57
44
	
	
	
	
(b)
0.24k
2.9*

2.82
5.28
3.86

26.3*
42*
64*
47*
80. 2m
71. 5m
80. Om
65. 9m
Estimated
0.285
2.43

2.95
4.42
2.95

35.6
44.0
93.9
44.0
115
54.1
115
54.1
Percent
Errorcc
+19
-16

+5
-16
-24

+35
+5
+48
-6
+44
-24
+44
-18
                                  -116-

-------
Table 23.  Continued
Chemical Class/Chemical
3 , 4-Dimethylphenol
3 , 5-Dimethylphenol
2 , 3-Dichlorophenol
2 , 4-Dichlorophenol
H. NITROBENZENES
Nitrobenzene**
p,-Nitrophenol
p.-Nitrotoluene
g^Nitrotoluene
W I . AMINOBENZENES
N, N-Dimethylaniline**
Aniline
g-Chloroaniline
2 , 4-Toluenediamine
J. ADDITIONAL SUBSTITUTED
BENZENES
Me thoxy benzene**
Benzonitrile**
Benz aldehyde
E+
-1.297
-1.542
-0.407
-0.122

0.674
-0.246
0.363
0.479
-1.7
-1.3
-0.901
-2.666

-0.778
0.562
0.22
1012 kOH (cm3molecule~1s~1)
Exper:
(a)
	
	
	
	

0.14
0.90
	
**
148
117
	
	

19.6
0.333
13
mental
(b)
81. 4m
113m
1.66n
1.06n

0.149
0.90
0.70
0.95
148P
111*
83. Or
192s

17.3*
0.33
12.9*
Estimated
115
200^
7.27
3.02

0.251
4.42
0.805
0.605
200U
136
53.6
200t

23.8
0.356
17.1
Percent
Error00
+41
+77
+340
+ 190

+68
+390
+15
-36
+35
+23
-35
+4

+38
+8
+33
                                  -117-

-------
Table 23.  Continued
Chemical class/Chemical
Acetophenone
Thiophenol
(Mercaptobenzene)
Benzyl alcohol
Tetralin (1,2,3,4-Tetra-
hydronaphthalene)
Indan (2,3-Dihydro-lH-
indene)
Fluorene
1 , 4-Benzodioxin
2 , 3-Dihydrobenzofuran
2 , 3-Benzofuran
E+
0.10
-0.604
-0.295
-0.359
-0.359
Ring A:
-0.243dd
Ring B:
-0.243dd
-0.731
-0.842
-0.48bb
lO^ kOH (cm3molecule"~1s~1)
Experii
(a)
	
	
	
	
	
___
25
37
	
dent a 1
(b)
2.74n
11. 2V
22.9
34.3*
9. ay
13. Oz
25.2aa
36.6aa
37.3aa
Estimated
1.61
13. 3W
7.99
11.2
9.09
9.37
33.0
36.3
65.2
Percent
Errorcc
-41
+19
-65
-67
-1
-28
+ 31
-1
+75
a Experimental data from Atkinson (1987).
b Experimental data from Atkinson (1989).
c Experimental data from Atkinson and Aschmann  (1985).
d For biphenyl. kpu was reported as 8.5, 8.06, and 5.8 x 10~12
  Therefore, the average value is 7.5 x 10~12cm3molecule"1s~1.
d/ Experimental data from Ohta and Ohyama  (1985).
e In the estimation of kpjj / it was assumed that the OH radicals add
  separately to the olefinic group and the aromatic ring.  Thus,
  k(3) [=ka(}ci nar] was calculated for the olefinic group using equations
  90 and 91 and with C[C6H5-] = 1.00; k(7) [ = kj^ ar ] was calculated  for
  the aromatic ring using equations 127, 128a, 129'and ^T,a+    Caa'
  Illustrative Example IV.P.2. trans-1-phenyl-l-propene.
                                                             See
                                  -118-

-------
Table 23.  Continued
 Experimental data from  Bignozzi  et  al.  (1981).
3 Experimental data from  Chiorboli et al.  (1983).
h Experimental data from  Wanner  and Zetzsch (1983).
1 Experimental data from  Rinke and Zetzsch (1984).
3 Experimental data from  Ravishankara et  al.  (1978a).
k Experimental data from  Atkinson  et  al.  (1985a).
1 Calculated from the  structure:                         Cl
                                           RING A  RING B

m Experimental data  from Atkinson  and  Aschmann (1989).
n Experimental data  from Nolting et  al.  (1987)  and Atkinson (1989).
I
Average of the experimental data of Witte et al. (1986) and Zetzsch
(1982) as reported in Atkinson (1989).
 P  Experimental data  from Atkinson  et  al.  (1987).
 9  The  estimated kgg  was  247  x  10~12 cm3molecule~1s"1.   However,  this
   exceeds the collision  rate so  that  the  value  of  kOH  was  set equal to
   200  x  10~12 cm3molecule~1s"1 [Atkinson  (1987)].
 r  Experimental data  from Wanner  and Zetzsch (1983).
 3  Experimental data  from Becker  et al.  (1988) .
 t  The  estimated value  of )CQH was 8150 x 10~12 cm3molecule~1s~1.   This
   exceeds the collision  rate so  that  the  value  of  kOH  was  set at
   200  x  10~12 cm^molecule^s"1 [Atkinson  (1987)].
 u  The  estimated value  of kQH was 466  x  10~12 cm3molecule"1s"1.   However,
   this exceeds the collision rate  so  that the value  of kOH was set at
   200  x  10~12 cB^molecule^s"1 [Atkinson  (1987)].
 v  Experimental data  from Barnes  et al.  (1986).
                                     -119-

-------
Table 23.  Continued


w For the thiol group on an aromatic ring, it was assumed that Jc(4) =
  k(-SH) = o [Meylan(1990)].

x Experimental data from Atkinson and Aschmann (1988a).

Y Experimental data from Baulch et al. (1986) as reported by
  Atkinson (1989).

2 Experimental data of Klopffer et al. (1986) and Becker et al.
  (1984) as reported by Atkinson (1989).

aa Experimental data from Atkinson  et al. (1989).

bb In calculating k(7), it was assumed that the molecular structure of
   2,3-benzofuran can be approximated by the molecular structure of
   l-vinyl-2-vinyloxybenzene.  (It should be noted that this compound is
   a polynuclear aromatic hydrocarbon and should probably be considered
   in Section III.D.2.k.  However, since no ionization potential is
   available, it cannot be calculated using equation 138.)

cc Based on the experimental kOH data given in the third column,
   Experimental/(b).

dd Calculated from the molecular structure
                                          Ring A   Ring B

* Recommended value by Atkinson (1989) with the rationale for the
  recommendation and the uncertainty in the recommendation.
                                     -120-

-------
and this result is listed in the second column of Table 23.  For
benzene, C-H abstraction is given by k(l) = k(l,UNS CH) = 0
(Table 1); OH addition to the aromatic ring can be estimated
using equations 127, 128, 129, and 130 so that k(7) = ka(jd ar =
2.04 x 10~12 cm3molecule~1s~1.  From equation 20, kOH = Ml) +
k(7).  Therefore, using the above data in this equation yields

           kOH = 2.04 x 10"12 cm3molecule~1s"1            (131)
This result is listed in the fifth column of Table 23.  Based
on the recommended value of kOH from Atkinson (1989) listed in
the fourth column, the percent error for benzene is +66 which
is relatively poor.
     The experimental value of kOH for biphenyl is listed in
the third column of Table 23 as obtained from Atkinson and
Aschmann  (1985) while the recommended value is given in Column
4 as obtained from Atkinson (1989).  For biphenyl, kOH can be
calculated as follows.  From equation 20, for each phenyl ring
               kOH = k'(l) + k'(7)                        (132)

where k'(l) represents the H-atom abstraction rate constant for
the aromatic ring while k'(7) represents the OH addition to the
aromatic ring.  Therefore, for biphenyl, which contains two
aromatic rings,

                   2kOH = Z
                             -121-

-------
For C-H abstraction from the aromatic ring, k'(l) = k(l,UNS CH)
= 0.  For OH addition to the aromatic ring, ^o+  was
calculated according to the rules listed in Section III.D. and
was estimated to be
                    f = -0.179                            (134)

and this result is listed in the second column of Table 23.
Using equations 127, 128, 129, and 134, k'(7)  was estimated to
be 3.56 x 10~12 ca^molecule'^-s'1.  Using the above results of
k'(l) and k'(7)  in equation  133  gives

                 7.12 x 10~12 cm3molecule~1s~1            (135)

and this result is listed in the fifth column of Table 23.  The
percent error is -1 which is superb.
III.D.2.b.  Alkylbenzenes
     Experimental kOH data is available for 14 alkylbenzenes,
Table 23.B.  The rate constant k_ for each alkylbenzene was
calculated as follows.  The rate constant for H-atom
abstraction from the alkyl group [k(la)] was calculated using
equation 28; for H-atom abstraction from the phenyl ring,
k(l,UNS CHV - 0.  Therefore, k(l) = k(la).  The rate constant
for OH addition to the aromatic ring [k(7)] was calculated
using equations 127, 128, and 129 and the value of
obtained using the rules listed in Section III.D.  The value of
kOH was then calculated from equation 20, which is the sum of
                             -122-

-------
k(l) and k(7); and these results are listed in Table 23.B. for
each compound along with the values of  ^Tff* and the percent
error.  For -butylbenzene, which was not used to derive
equation 125, the percent error is +10 which is excellent
tentativley confirming this equation for the alkylbenzenes.
For all 14 alkylbenzenes, the average percent error ranged from
+14 to -35 which ranged from excellent to very good.  More
experimental kQH data are needed on a number of additional
alkylbenzenes to confirm the S/R relationships of Atkinson.
III.D.2.C.  Alkenylbenzenes
     Experimental k0H data is available for four alkenyl-
benzenes, Table 23.C.  These experimental kOH data were not
used by Atkinson (1987) to derive equation 125.  The rate
constant JCQH for each alkenylbenzene was calculated as follows.
The rate constant for H-atom abstraction was calculated in the
same manner as described in Section III.D.2.b.  For OH addition
to the unsaturated carbon-carbon functional groups, it was
assumed that OH added to the olefinic group and the aromatic
ring separately as postulated by Atkinson  (1987).  For the
olefinic group, k(3) C=fcadd,narJ was calculated using equations
                                is           ou
90 and 91  (for these compounds ka(j nar and ka(j(j nar are zero);
for the aromatic ring, k(7) [= kad(j ar] was calculated using
equations  127, 128, and 129 and the value of J^a+ was
calculated from the rules  listed in Section III.D.  The value*
of kOH were then calculated from the sum of k(l), k(3), and
k(7)  [equation 20], where  applicable, and these results are
                             -123-

-------
listed in Table 23.C. along with the values of a+ and the
percent error.
     For th four alkenylbenzenes, only l-phenyl-2-methyl-l-
propene had a percent error greater than +100 (+170).  For the
remaining three alkenylbenzenes, the average percent error
ranged from +7 to -51.  Overall, these results ranged from
superb to good, tentatively confirming equation 125; but more
experimental data on a number of additional alkenylbenzenes are
needed to confirm the S/R relationships of Atkinson for this
class of aromatic compounds.  Perhaps these S/R relationships
should be modified using the fact that there is strong
interaction between the unsaturated carbon-carbon bonds in the
olefinic groups and the phenyl rings (i.e., resonance) so that
there should be unique group rate constants for these
conjugated groups  (e.g., as described in Section III.B.I. for
conjugated diolefins).
III.D.2.d.  Halogenated Benzenes
     Experimental kQK data is available for 10 halogenated
benzenes, Table 23.D.  Nine of these compounds were used by
Atkinson to derive equation 125.  The values of  J^"1"/ kOH' and
the percent error were calculated as.described previously and
these results are  listed in Table 23 for each halobenzene.  For
these chemicals, only fluorobenzene had a percent error greater
than +100 (+270);  and this compound was omitted in calculating
the average percent error for all the halogenated benzenes.
                             -124-

-------
Only n-propyl pentafluorobenzene was not used by Atkinson to
derive equation 125.  The percent error for this compound was
-5 which ia excellent, tentatively confirming this equation.
However, more experimental )CQH data are needed for additional
halobenzenes to confirm this equation.  For all 9 halogenated
benzenes, the averaqe percent error ranged from +48 to -16.
Overall, these results ranged from good to excellent.  More
experimental kOH data is needed for fluorobenzene to determine
why this compound had such a large percent error.
III.D.2.e.  Haloalkylbenzenes
     Experimental kQH data is available for 3 haloalkyl-
benzenes, Table 23.E.  The experimental )CQH data for the first
two compounds were used by Atkinson (1987) to derive equation
125.  The values of   $^a+ '  ^H' and tne percent error were
calculated as described previously and these results are listed
in Table 23 for each compound.  For benzyl chloride, which was
not used by Atkinson  (1987) to derive equation 125, the percent
error was -16 which was excellent, tentatively confirming this
equation for the haloalkylbenzenes.  For these 3 compounds, the
average percent error ranged from +19 to -14 which is
excellent.  However, more experimental kOH data for additional
compounds in this class are needed to confirm the S/R
relationships of Atkinson.
                             -125-

-------
III.D.2.f.  Monochlorobiphenyls
     At the request of Leifer, Atkinson {under a  (1981) ORD
cooperative agreement} measured kOH for three monochloro-
biphenyls.  The experimental values of k0H for three
monochlorobiphenyls are listed in Table 23 as obtained from
Atkinson and Aschmann (1985).  These experimental kOH data were
not used by Atkinson to derive equation 125.  To calculate k^u
                                                            Orl
for the three monochlorobiphenyls, each ring was considered
separately {i.e., C6H5[Ring A] 	C6H4Cl[Ring B]}.  The values
of  ]P<*+ were then calculated for each ring in the standard
manner and k'(l)  and k'(7) were calculated as described
previously.  The overall rate constant is the sum of the rate
constants for each ring.  Therefore, for each monochloro-
biphenyl

kOH = 2k'(l,UNS CH) + kadd,ar,(Ring A) + kadd/ar (Ring B)  (136)

The estimated values of kOH for each monochlorobiphenyl are
listed in Table 23.F. along with the values of  $^ff+ for each
ring, and the percent error.  The estimation of kOM for
3-chlorobiphenyl is given in Illustrative Example IV.P.9.
     The average percent error for all three monochloro-
biphenyls ranged from +5 to -20 which ranged from superb to
excellent.  All these results indicate that equation 125 is
valid for this class of compounds.  However, more experimental
k0H data are needed for this class of compounds to confirm
equation 125.

                              -126-

-------
III.D.2.g.  Hydroxybenzenes
     Experimental kOH data is available for phenol and 11
substituted phenols, Table 23.G.  The values of   ^2+ >
estimated kQH/ and the percent error were calculated for these
compounds as described previously and these results are
summarized in Table 23.G.  For 3,5-dimethylphenol, the
calculated value of  a+ was -1.542 and the estimated value of
kadd ar was e(3Ual to 246.4 x 10~12 cm3molecule~1s~1.  The
second-order rate constant kOH [=k(la) + k(-OH) + k(l,UNS CH)
+ ka(jd arl was tnen equal to 247 x 10~12 cm3molecule~1s"1.  In
this case, the estimated value of kOH exceeded the collision
rate so that an upper limit must apply.  Therefore, Atkinson
(1987) recommended that kOH be set at 200 x 10~12
cm3molecule~1s~1 and this is the value entered into the fifth
column of Table 23.G.
     Inspection of the percent error data in the last column
indicated that two of the phenolic compounds had a percent
error greater than +100  [2,3-dichlorophenol (+340); 2,4-
dichlorophenol (+190)] and these values were omitted in the
estimation of the average percent error.  For the six chemicals
below the dashed line which were not used to derive equation
125, the average percent error ranged from +52 to -21 and,
therefore, ranged from good to very good, tentatively
confirming the validity of equation 125 for the phenolic
compounds.  The average percent error for the 10 remaining
compounds was +42 to -16 and, therefore, ranged from good to
                             -127-

-------
excellent.  However, more experimental data is needed for
2,3-dichlorophenol and 2,4-dichlorophenol to see why these two
compounds had a large percent error.

III.D.2.h.  Nitrobenzenes
     Experimental JCQH data is available for nitrobenzene and
three substituted nitrobenzenes, Table 23.H. The values
of   ^,a+ i *OH an<* tne Percent error were calculated for
these four compounds as described previously and these results
are summarized in Table 23.H.  For the three compounds below
the dashed line in Table 23.H. o-nitrophenol had a percent
error of +390 and was omitted in calculating the average
percent error.  The percent error for the other two compounds
was +15 and -36 which is excellent and good, respectively.  The
average percent error for the three remaining compounds ranged
from +42 to -36 which is very good.  More experimental kOH data
are needed for o-nitrophenol and for other substituted nitro-
benzenes to confirm equation 125 for this class of compounds.
III.D.2.i.  Aminobenzenes
     Experimental KQJJ data is available for aniline and three
substituted anilines, Table 23.1.  For the compound
N,N-dimethylaniline, the calculated value of ^a+ was -1.7.
The second-order rate constant kOH t= Mia) + k(l,UNS CH) +
k(5) + kaaci ar] was then equal to 466 x 10~12 cm3molecule~1s~1.
In this case, kOH exceeded the collision rate so that it is set
at 200 x 10~12 cm3molecule"1s"1  [Atkinson  (1987)] and this

                             -128-

-------
value was entered into the fifth column of Table 23.1.  In a
similar manner for 2,4-toluenediamine, ^o+ = -2.666, k(7) =
8110 x 10~12, and k0H was 8150 x 10~12 cm3molecule"1s~1.  Since
this exceeds the collision rate, k0n was set a^ 200 x 10~12
cm3molecule~1s~1 [Atkinson (1987)] and this value was entered
in the fifth column of 23.1.
     For the three amino compounds below the dashed line, the
average percent error was +14 to -35 and therefore ranged from
excellent to very good.  These results tentatively confirm
equation 125 for the substituted aniline compounds.  For all 4
compounds, the average percent error ranged from +21 to -35 and
are very good.  More experimental data is need for additional
chemicals in this class to confirm equation 125.

III.D.2.J.  Additional Substituted Benzenes
     The experimental kOH data at 298 K for twelve additional
substituted benzenes [methoxybenzene, benzonitrile,
benzaldehyde, acetophenone, thiophenol, benzyl alcohol,
tetralin  (1,2,3,4-tetrahydronaphthalene), Indan (2,3-dihydro-
IH-indene), fluorene, 1,4-benzodioxan, 2,3-dihydrobenzofuran,
and 2,3-benzofuran] are summarized in Table 23.J.  The values
of ]5^tf+ *OH' an^ **ne Percent error were calculated as
described previously and these results are listed in Table 23
for each compound.  For 2,3-benzofuran, ^o+ was calculated
assuming that this chemical can be represented by the molecular
                             -129-

-------
structure of l-vinyl-2-vinyloxybenzene5.  For 2,3-

dihydrobenzofuran, Atkinson (1987) estimated kQH but did not

include a ring strain factor F(5) [for the five membered ring]

in calculating k(lc).  To be consistent with the S/R

relationships in this report,  the ring strain factor was

included in the estimation of k(lc).   The same comments apply

to indan and fluorene.

     For thiophenol, as an approximation, it has been assumed

that there is no interaction of OH radicals with the -SH group

on the aromatic ring; hence, k(4) = k(-SH) = 0 [Meylan(1990)].

Ten of these compounds were not used by Atkinson to derive

equation 125.  The average percent error ranged from +40 to

-34 which is  very good to good, tentatively confirming

equation 125.  However, more experimental kOH data are needed

for additional compounds of these types to confirm this

equation.  For all 12 additional aromatic compounds, the

average percent error was 34 which was very good.


III.D.2.k.  Polyaromatic Hydrocarbons

     Table 24 summarizes the experimental  k.u data for nine
                                            
-------
Table 24.  Comparison of Experimental and Estimated Values of kOH  for
           Fused Ring Polyaromatic Hydrocarbons  [Underlined Values of
           KQJJ Were Used by Atkinson (1987) and Atkinson in Biermann
           et al. (1985) to Derive Equation 137]
Chemical

Naphthalene
1-Methyl-
naphthalene
2 -Methyl -
naphthalene
2, 3 -Dimethyl-
naphthalene
Anthracene
Phenanthrene
flitro-
naphthalene
2-Nitro-
naphthalene
1,4-Dichloro-
naphthalene
lonization
Potential3
(eV)
8.13
8.13
8.13
8.13
7.55
8.1
8.13
8.13
8.13
E*+

0.000
-0.311
-0.311
0.377
0.000
0.000
0.674
0.674
0.513
10 12 kOH (cm3mo:
Experimental
21.6*
53. Ob
52.3^
s
76. 8b
112
31*
5.4d
5.6*
5.8e
Lecule~1s~1)
Estimated
21.4
56.3
56.3
69.5
91.2
22.9
2.63
2.63
4.37
Percent
Error
-1
+6
+8
-10
-19
-26
-51
-53
-25
a  lonization potential (IP) in electron Volts  (eV) of the parent chemical
   as obtained from Atkinson (1987) and Weast (1976-1977).

k  Experimental data from Atkinson and Aschmann  (1987).
. *
D  Experimental data from Atkinson and Aschmann  (1986).

c  Experimental data from Biermann et al.  (1985).

d  Experimental data from Atkinson et al.  (1989d).

e  Experimental data from Klopffer et al.  (1986)  and Becker et al.  (1984)
   as reported in Atkinson  (1989).
                                     -131-

-------
methylnaphthalenes, and 2,3-dimethylnaphthalene, Atkinson
(1987) and Atkinson in Biermann et al. (1985) formulated the
equation
        lo9lOkadd,PAH = -1-89 - 1-08(IP) - 1.35 a+       (137)
where kadd PAM represents the second-order rate constant for
the addition of OH radicals to the fused polyaromatic ring in
the units cm3molecule~1s~1, IP represents the ionization
potential of the unsubstituted polyaromatic ring in electron-
volts (eV) , and ^T^"1" represents the sum of the electrophilic
substituent constants of Brown and Okamota (1958) derived for
the monocyclic substituted portion of the molecule to allow for
the effects of substituted groups on the reactivity.
Conversion of equation 137 to the more useful form by adding
+12 to both sides of the equation yields
     lo9lOk'add,PAH = I-0-11 - 1.08(IP) - 1.35   a          (138)
               1012kadd/PAH = kadd/PAH

Thus, when kadd/PAH is computed using equations 138 and 139,
then kadd PAH  is multiplied by 10~12 to obtain kadd PAH*
    From equation 19, it is seen that

                   M) = *add, PAH
       Using equations 20,  138, 139,  and 140, along with  the
appropriate group rate constants and  substituent factors  from
                             -132-

-------
Tables 1 and 2, the appropriate electrophilic substituent
factors from Table 22, the ionization potential of the parent PAH
from Weast (1976-1977),  and the appropriate experimental values
of kOH from the literature, the values of J^cr+ , kOH, and the
percent error were calculated for nine PAH compounds in the
standard manner.  These results are summarized in Table 24.
     For the three compounds below the dashed line, which were
not used to derive equation 137, the average percent error was
-43 which was good, tentatively confirming equation 137..  For all
nine PAH compounds, the average percent error ranged from +7 to
-26 which ranged from superb to very good.  More experimental k0n
data, however, are needed for additional PAH compounds to confirm
equation 137.

III.D.3.  Summary
     Table 25 summarizes the average percent error in kOH
for the reaction of OH radicals with aromatic and polyaromatic
compounds as obtained from Tables 23 and 24.  kOH was estimated
for a total of 77 aromatic and polyaromatic compounds and these
results were compared to the experimental values.  Only five of
these compounds had a percent error greater than +100 [1-phenyl-
2-methyl-l-propene(+170); fluorobenzene (+270); 2,3-dichloro-
phenol  (+340); 2,4-dichlorophenol (+190); o-nitrophenol (+390)];
and these compounds were omitted in the estimation of the average
percent error.  Of the 72 remaining aromatic compounds, kOH was
                              -133-

-------
Table 25.  Summary of the Average Percent Error in kOH at 298 K
           for a Number of Chemicals in Several Classes of
           Aromatic and Polyaromatic Compounds and for All
           Chemicals in These Classes
Chemical Class/Chemical
Benzene
Biphenyl
Alkylbenzenes
Alkenylbenzenes
Halobenzenes
Haloalkylbenzenes
Monochlorobiphenyls
Hydroxybenz enes
Nitrobenzenes
Aminobenzenes
Polyaromatic Hydrocarbons
ADDITIONAL SUBSTITUTED
BENZENES
Methoxy benzene
Benzonitrile
Benz aldehyde
Acetophenone
Thiophenol
( Her captobenz ene )
Benzyl Alcohol
Number of
Chemicals
1
1
14
3a
9b
3
3
10
3d
4
9

1
1
1
1
1
1
Average Percent
Error
From
+66
	
+14
+7
+48
+19
+5
+42
+42
+21
+7

+38
+8
+33
	
+19
	
To
	
-1
.-35
-51
-16
-14
-20
-16
-36
-35
-26

	
	
	
-41
	
-65
                             -134-

-------
Table 25.  Continued
Chemical Class/Chemical
Tetralin (1,2,3,4-Tetra-
hydr onaph tha 1 ene )
Indan (2,3-Dihydro-lH-
Indene)
Fluorene
1 , 4-Benzodioxin
2 , 3-Dihydrobenzof uran
2 , 3-Benzofuran
All Compounds Not Used to
Derive Equation 125
All Compounds Not Used to
Derive Equation 137
All Compounds
Number of
Chemicals
1
1
1
1
1
1
30
3
72
Average Percent
Error
From
_ 
-1
	
+31
	
+75
+29
	
+32
To
-67
	
-28
	
-1
	
-29
-43
-28
a Estimates of kOH were made for four alkenylbenzenes.
  However, the percent error for l-phenyl-2-methyl-l-propene
  was greater than +100  (+170) and was not used in the
  estimation of the average percent error for this class of
  compounds.

b Estimates of kOH were made for ten halobenzenes.
  However, the percent error for fluorobenzene was greater
  than +100  (+270) and was not used in the estimation of the
  average percent error for this class of compounds.

c Estimates of kpK were made for twelve hydroxybenzenes.
  However, 2,3-dichlorophenol and 2,4-dichlorophenol had
  errors greater than +100 [+340 and +190] and were
  omitted in the calculating the percent error for this
  class of compounds.

d Estimates of KQH were made for four nitrobenzenes and the
  percent error for o-nitrophenol was greater than +100  (+390),
  This result was omitted in calculating the percent error for
  this class of compounds.
                              -135-

-------
estimated for 63 chemicals using equation 125; kOH was
estimated for 9 polyaromatic compounds using equation 137.
Thirty of the 63 aromatic chemicals were not used by Atkinson
to derive equation 125.  The average percent error of these 30
compounds was  29 which is very good, thereby tentatively
confirming equation 125.  Three of the 9 polyaromatic compounds
were not used by Atkinson to derive equation 137.    The
average percent error of these three compounds is -43 which is
good, tentatively confirming equation 137.  The average percent
error for all 72 aromatic and polyaromatic compounds ranged
from +32 to -28 which is very good.  However, more experimental
kOH data are needed in several classes of aromatic and
polyaromatic compounds to confirm the S/R relationships of
Atkinson (i.e., equations 125 and 137).
      It should be noted that for substituent groups which
result in large negative values of  a+ the estimated rate
constants from equations 125 and 137 can exceed the collision
rate so that an upper limit must apply.  This was probably the
case for N,N-dimethylaniline, 2,3-dimethylphenol, and
2,4-toluenediamine which had estimated values of kOH greater
than 200 x 10~12cm3molecule~1s~'1 (the upper limit collision
rate).  Therefore, Atkinson  (1987) recommended that for
aromatic and polyaromatic compounds in which the estimated rate
constant kOH at 298 K exceeds 200 x 10~12cm3molecule~1s~1/ the
estimated rate constant kOH should be set equal to 200 x
10~12cm3molecule~1s""1.
                             -136-

-------
     If one compares the average percent error for all the
specific classes of compounds, it is evident that the aromatic
and polyaromatic compounds have the largest percent error.
[See Tables 8, 17, 21, 23 and 24.]  From equations 125 and 137,
it is seen that the estimated  value of kadd ar is an
exponential function of ^o+ which is in turn related to the
individual values of a and a for specific  functional groups.
Thus, any small error in these a"1" values will have a large
effect on the estimated value of kOH and this is probably the
reason why aromatic and polyaromatic compounds have the largest
relative average percent error.
III.E.  Summary of the Results for the Estimation of kOH
        for All Chemicals in a Number of Classes of Chemicals
        by the Structure/Reactivity Relationships of Atkinson
        of the University of California/Riverside.
     The second-order rate constant kOH at 298 K was estimated
by the S/R relationships developed by Atkinson at the
University of California/Riverside for 405 organic chemicals
covering a wide variety of chemical classes and these results
were compared to the experimental values.  These chemical
classes were:  alkanes  (acyclic and cyclic); haloalkanes;
carbonyl compounds such as aldehydes, ketones, esters, etc.;
ct-dicarbonyls such as glyoxal, etc.; alcohols and glycols;
ethers  (acyclic and cyclic); nitrates; nitriles; alkenes,
conjugated and nonconjugated; ketenes; alkynes; 1,2-dienes
(allenes); thiols; sulfides; disulfides; N-hydroxylamines;
N-nitrosamines; N-nitroamines; hydrazines; alkyl
                             -137-

-------
phosphates/thiophosphates; dialkylchlorophosphorothionates;
alkyl phosphoroamidates/ phosphorothioamidates; benzene and
biphenyl; alkyl benzenes; alkenyl benzenes; halogenated
benzenes; haloalkylbenzenes; monochlorobiphenyls; hydroxy-,
nitro-, and aminobenzenes; methoxy and cyanobenzenes; aromatic
aldehydes; polyaromatic hydrocarbons; and other aromatic
compounds.  Of the 405 chemicals, 20 had percent errors greater
than +100.  The value of +100 was chosen so that only a minimum
number of chemicals would be dropped from the total number of
chemicals used to obtain the average percent error.  For the
remaining 385 chemicals in a number of chemical classes, the
average percent error ranged from +21 to -19 which is
excellent.  One hundred fifty-four chemicals were not used by
Atkinson to derive all the parameters in the S/R relationships
and, therefore, were good candidates to test the validity of
these S/R relationships.  The average percent error of these
154 chemicals ranged from +24 to -20 which ranged from very
good to excellent, thereby confirming the S/R relationships of
Atkinson.  However, a few of the classes of chemicals had a
minimum number of chemicals so that more experimental kOH data
are needed for additional chemicals in these classes to
corroborate and/or refine some of the S/R relationships
developed by Atkinson.  In addition, more experimental kgjj data
are needed for the 20 chemicals with errors greater than +100
to get a better estimate of the percent error for each chemical
and for all chemicals.  It should be noted- that, in general,
                             -138-

-------
the estimated values of kOH for the first member of a given
class of chemicals has the greatest deviation from the
experimental value (i.e., it had the largest percent error).
Therefore, more experimental kOH data are needed for the first
member of a given class of chemicals.  Table 26 summarizes the
statistical data for all the compounds used in the analysis of
the S/R relationships of Atkinson.

IV.  Illustrative Examples:  Use of the Structure/Reactivity
     Relationships of Atkinson to Estimate the Second-Order
     Rate Constant (kOH) fr tne Reaction of Hydroxyl
     Radicals with Organic Chemicals in the Gas-Phase at
     298 K in Air at Atmospheric Pressure

    (1)   A large number  of examples  (56) are given in this
         section to illustrate the methods of estimating k-..
                                                          Uii
         with the S/R relationships of Atkinson and to cover
         most of the classes of organic chemicals evaluated in
         this report.

    (2)   The group rate  constants listed in Tables l, 9, 11,
         and 12 are reported with a numerical value of
          1012kOH    *n calculating OH radical addition to the
         aromatic and polyaromatic rings, equations 127 and
          138 were used where k'add/ar = 1012*add ar (equations
          128 and  139) .   Thus, kOH was calculated for all
         examples without the factor 10~12. The final value of
         kOH  (Estimated) was then reported with the factor
          10~12 and the units cm3molecule~1s~^-.
                             -139-

-------
Table 26.  Summary of the Statistical Data for All the Compounds Used
           in the Analysis of the S/R Relationships of Atkinson
Chemical
Class/
Chemical
Alkanes
Saturated
Haloalkanes
Saturated
Carbonyl
Compounds
Saturated
Alcohols
and Glycols
Saturated
Ethers
Saturated
Nitrates
Saturated
Nitriles
Unsubsti-
tuted
Alkenes
Substituted
Alkenes
Conjugated
Dienes
Alkynes
Allenes
Saturated
Thiols
Total
No. of
Chemicals
50
32
52
18
36
17
2
39
24
13
5
3
9

Number3
Dropped
0
2
4
0
4
1
0
0
2
0
0
0
0
Phpmi nal a Poma i rH nrr
NO.
50
30
48
18
32
16
2
39
22
13
5
3
9
No.b With
(+) and
(Ave %)
Error
22(+12)
15(+21)
15(+26)
5(+20)
18 (+27)
8 (+20)
	
18 (+11)
12(+20)
6(+5)
2(+9)
2 (+10)
2 (+24)
No. With
(-) and
(Ave.%)
Error
28(-10)
15(-28)
33(-19)
13(-19)
14(-22)
8 (-10)
2 (-5)
21(-11)
10(-21)
7 (-17)
3(-16)
K-io)
7(-10)
Chemical Below
DachoH T,i npO
No.
17
15
28
13
0
1
0
34
4
5
2
0
0
No.b With
(+) and
(Ave. %)
Error
5(+12)
7(+26)
8(+39)
4(+19)
	
	
	
13 (+16)
2(+21)
1(+10)
	
	
	
No. With
(-) and
(Ave.%)
Error
12(-10)
8(-37)
20(-22)
9(-16)
	
1(-6J
	
21(-11)
2(-16)
4(-24)
2(-21)
	
	
                                     -140-

-------
Table 26.  Continued
Chemical
Class/
Chemical
Saturated
Sulfides
Saturated
Disulf ides
Saturated
Amines
N-Hydroxyl-
araines
N-Nitros-
amines
Ll-Nitra-
Hines
Hydrazines
Alkyl
Phosphates/
Thiophos-
phates
Dialkyl
Chloro-
Phosphoro-
thioates
Alkyl
Phosphoro-
amidates/
Phosphoro-
thio-
amidates
Benzene
Total
No. of
Chemicals
5
1
6
1
1
1
2
6
1
4
1
Numbera
Dropped
0
0
0
0
0
0
0
0
0
2
0
Phemirals R^m^-ininrf
No.
5
1
6
1
1
1
2
6
1
2
1
No.b With
(+) and
(Ave %)
Error
3 (+6)
	
2(+5)
1(+14)
	
l(+25)
4(+20)
-l(+3)
	
l(+66)
No. With
(-) and
(Ave.%)
Error
2(-27)
l(-4)
4(-9)
l(-24)
	
l(-25)
l(-34)
2(-8)
	
2(-58)
	
Chemical Below
nash*>rt T.in*C
NO.
2
0
0
0
0
0
0
0
0
0
0
No.b With
(+) and
(Ave. %)
Error
1(+10)
_.  .
	
	
	
	
	
	
	

No. With
(-) and
(Ave.%)
Error
1(-10)
	
	
	
	
	
	
	
	
	
                                     -141-

-------
Table 26.  Continued
Chemical
Class/
Chemical
Biphenyl
Alkyl-
benzenes
Alkenyl-
benzenes
Halo-
benzenes
Haloalkyl-
benzenes
Monochloro-
biphenyls
Hydroxy-
benzenes
Nitro
benzenes
Amino-
benzenes
Poly-
aromatic
Hydro-
carbons
Additional
Substituted
Aromatic
Compounds
All
Compounds
Total
No. of
Chemicals
1
14
4
10
3
3
12
4
4
9
12
405
Number3
Dropped
0
0
1
1
0
0
2
1
0
0
0
20
rhptrn rials Pevma i ni net
NO.
1
14
3
9
3
3
10
3
4
9
12
385
No.b With
(+) and
(Ave %)
Error
	
3 (+14)
2 (+7)
5(+48)
K+19)
l(+5)
7(+42)
2(+42)
3 (+21)
2 (+7)
6(+34)
170(+21)
NO. With
(-) and
(Ave.%)
Error
1(-1)
ll(-35)
1(-51)
4(-16)
2(-14)
2(-20)
3(-16)
l(-36)
l(-35)
7(-26)
6(-34)
215(-19)
Chemical Below
DasVieri T.i nfG
NO.
0
1
3
1
1
3
6
2
3
3
10
154
No.b With
(+) and
(Ave. %)
Error
	
1(+10)
2(+7)
	
	
l(+5)
4(+52)
1(+15)
2 (+14)
	
4 (+40)
56(+24)
NO. With
(-) and
(Ave.%)
Error
	 '
	
K-51)
K-5)
1(-16)
a
2(-21)
K-36)
l(-35)
3(-43)
6(-34)
98(-20)
                                     -142-

-------
Table 26.  Continued

  Chemicals with percent error greater than +100.  The value of +100 was
  chosen so that a minimum number of chemicals would be dropped from the
  total number of chemicals used to obtain the average percent error.

b The number of chemicals which had an average (+)  percent error including
  those with zero error.

c The number of chemicals not used by Atkinson to derive the parameters
  in the S/R relationships.  These data represent the best test for the
  reliability of the S/R relationships of Atkinson.
                                     -143-

-------
    (3)   In calculating the percent  error,  the factor 10~12



         was omitted  since this  factor  cancels out.





IV.A.  Alkanes (Acyclic and Cyclic)





IV.A.I.  2-METHYLPENTANE             (CH3) 2CHCH2CH2CH3





Using equations 20 and 28 and going  from carbon to carbon



sequentially from left to right  yields






kOH = k(l) = k(la) =  2k F(>CH-) + kg F2(CH3-)F(-CH2-)



      + k| F(>CH-)F(-CH2-) + k|  F(-CH2-)F(CH3-)



           + kg F(-CH2-)





Using the appropriate group rate constants  from Table  1  and the



appropriate substituent factors  from Table  2 yields





kOH = 2(0.144)(1.29)  + 1.83(1.00)2(1.29) +  0.838(1.29)(1.29)



    + 0.838(1.29)(1.00) + 0.144(1.29)






kOH =5.39





kOH(Estimated) = 5.39 x 10~12cm3molecule~1s~1





From Table 3.A., the  experimental value of  k-.. is 5.6  x  10~12
                                            VJtl


cm3molecule""^s~1.





Percent Error = [ (5.39-5.6)/5.6  ](100) = -4
                              -144-

-------
IV.A.2.  BICYCLO[3.3.0]OCTANE
                  CH2-CH-CH2
              H2C
                 \
:CH-
                  CH2-CH-CH2
Since this is a bicyclic compound, equations  20  and  43  are

used; and using the appropriate group rate constants and

substituent factors listed in Tables 1 and 2, respectively,

gives


kOH = Jc(l) = k(lc) =  [ 2kF2(-CH2-)F(>CH-) +  2kfF2(-CH2-)


                      +4k|F(-CH2-)F(>CH-)] F2(5)  F(8)
       2(1.83) (1.29)3 + 2(0.838) (1.29)2
                 + 4(0.838)(1.29)2
            (0.80)2(1.0)
kOH = 10.4
kOH(Estimated) = 10.4 x 10~12cm3molecule~1s~1


kOH(Experimental) = 11.0 x  10~12cm3molecule~1s~1    (Table  3.B.)


Percent Error = f (10.4-11.0) /li.o 1(100) =  -5
IV.A.3.  ISOPROPYLCYCLOPROPANE
                  CH-CH(CH3)2

               CH2	CH2
                              -145-

-------
Since this is a substituted cyclic compound, equations  20,  28,
and 43 are applicable; and using the appropriate group  rate
constants and substituent factors listed in Tables  1  and  2,
respectively, gives
kOH = k(l) = k(la) + k(lc)

k(la) = k.F2(CH3-)F(>CH-) + 2kgF(>CH-)

k(la) = 1.83 (1.00)2(1.29) + 2 (0. 144) (1.29)

k(la) = 2.73

k(lc) = {kF2(-CH2-)F(>CH-) +  2kF(-CH2-)F(>CH-)}F(3)

k(lc) = {1.83  (1.29)3 -I- 2(0.838) (1.29)2}(0. 017)

k(lc) = 0.12

kOH = 2.73 + 0.12 = 2.85

k0n[ Estimated] = 2.85 x 10~12cm3molecule~1s~1

kOK[ Experimental] = 2.84 x 10~12 cm3molecule~1s~1  (Table  3.B.)

                                     (100) = 0
Percent Error =   (2.85 - 2. 84) /2. 84

IV . B .  Haloalkanes

IV . B . 1 .  DIPLUOROMETHANB         CH2 F2

kOH = k(l) = k(la) = k| F2(F-) = 0.838 (0.099)2

                              -146-

-------
kOH = 0.821 x 10~2

kOH( Estimated) = 0.821 x I0~14cm3molecule~1s~1

kOH( Experimental) = 1.09 x 10"14cm3molecule~1s~1   (Table 4)

Percent Error = f (0.821-1.09) /1. 09 ](100) =  -25

IV. B. 2.  1,1-DIFLUOROETHANE              F2CHCH3

kOH = k(l) = k(la) =  kg F2(F-) F(CH3-)  + k  F(-CHF2)
    = 1.83(0.099)2(1.00) + 0.144(0.10)

kOH = 3.23 X 10~2

kOH  (Estimated) = 3.23 x 10~14cm3molecule"1s~1

kOH( Experimental) = 3.4 x 10"14cm3molecule~1s~1   (Table 4)

Percent Error = [ (3.23-3.4) /3. 4 ](100) =  -5

IV. C.  Car bony 1 Compounds

IV. C.I.  BUTMIAL             CH3CH2CH2CHO
kOH - k(l) = k(la) = kF(-CH2-)  + kF(CH3-)  F[-CH2CH(0)]
      + k|F(-CH2-)F[-CH(0)] + kg F[(0)]  F(-CH2-)
kOH = 0.144(1.29) + 0.838(1.00)(4.4)
      + 0.838(1.29)(0.76) +  1.83(8.8)(1.29)

kOH =25.5

kOH(Estimated) = 25.5 x  10~12cm3molecule"1s"1
                              -147-

-------
kOH( Experimental) = 23.5 x 10~12cm3molecule~1s~1   (Table 5. A.)


Percent Error = [ (25.5-23.5) /23. 5] (100) - +9


IV. C. 2.  TRICHLOROACETALDEHYDE              C13CCHO


kOH - k(l) = k(la) = kg F[(0)] F(C13C-)


kOH - 1.83 (8.8) (0.09)


kOH = 1.45


kOH( Estimated) =  1.45 x 10"12cm3molecule~1s~1


kOH( Experimental) = 1.73 x 10~12cm3molecule~1s~1   (Table 5. A.)


Percent Error - [ (1.45-1.73) /1. 73 ](100) = -16
IV. C. 3.  2-PENTANONE                   0
                                    CH3CCH2CH2CH3
kOH = k(l) = k(la) = k,F[-C(0)-] + k|F(-CH2-)
       kF(CH3-) F[-CH2C(0)-] 4- k,F(-CH2-)


kOH = 0.144(0.76) + 0.838(1.29) (0.76)
      + 0.838(1.00) (4.4) + 0.144(1.29)
kOH = 4.81


kOH( Estimated) = 4.81 x  10"12cm3molecule~1s~1


kOH( Experimental) = 4.9  x  10"12cm3molecule~1s1   (Table 5.B.)


Percent Error = [ (4.81-4.9) /4.9J (100) =  -2

                             -148-

-------
IV. C. 4 .  CYCLOBUTANONB           CH2	CH
                                 CH2 - C=:0




kOH = k(lc) - {kF[-CH2C(0)-][F(2nd-CH2C(0)-)]


              + 2kF(-CH2-)  P[-C(0)-]>F(4)




kOH - {0.838(4.4) (1.0) +  2(0.838) (1.29) (0.76)}(0. 22)




kOH =1.17




kOH[ Estimated] =  1.17  x 10~12cm3molecule~1s""1




kOH[ Experimental] =  0.87  x 10~12cm3molecule"1s~1  (Table 5.C.)




Percent Error -   [(1.17 - 0.87) /O. 87] (100)  = +34

                                      0 0
                                      It II
IV.C.5.  METHYL GLYOXAL            CH3C-C-H
kOH = k(l) = k(la)  =  kF[-C(0)-]  + k?F(0)F[-C(0) -]




kOH =  (0.144) (0.76) + 1.83(8.8) (0.76)




kOH =12.3




kOH (Estimated)  =  12.3 x 10"12cm3molecule""1s""1




kOH (Experimental)  =  17.2 x 10"12cm3molecule~1s~1  (Table 5.D.)




Percent  Error  -  [ (12.3-17.2) /17. 2] (100)  = -28
                              -149-

-------
                                              0
IV. C. 6.  ACBTYL CHLORIDE                   CH3C-C1

kOH = k(l) = k(la) = k,F[-C(0)Cl] =  0.144(0.50)

kOH = 0.0720

k0H  (Estimated) = 0.0720 x 10~12cm3molecule~1s~1

kOH  (Experimental) = 0.068 x  10~12cm3molecule~"1s~1  (Table 5.E.)

Percent Error = [  (0.0720-0.068) / 0.068]  (100)  =  +6
                                              0
                                              il
IV. C. 7.  a-PROPYL ACETATE                  CH3C-OCH2CH2CH3
kOH = k(l) = k(la) = kpF[-C(0)OR] + k|F[-OC(0)R]F(-CH2-)
                 + kgF(-CH2-)F(CH3-) + kF(-CH2-)

kOH = 0.144(0) + 0.838(1.5) (1.29) + 0. 838 (1. 29) (1. 00)
               + 0.144(1.29)

kOH = 2.89

kOH (Estimated) = 2.89 x  10~12cm3molecule"1s~1

kOH (Experimental) = 3.4  x  10~12cm3molecule~1s~1  (Table 5.F.)

Percent Error - [  (2.89-3.4) /3. 4] (100) =  -15

IV. D.  Alcohols and Glycols
                                      OH
                                       I
IV . D . 1 .  2 -PROPANOL                CH3 CHCH3

                              -150-

-------
Using equation 20





kOH = k(l) + k(2) = k(la)  +  k(-OH)






k(la) = 2k)F(>CH-) + k.F2(CH3-)F(-OH)





k(la) = 2(0.144)(1.29)  +  1.83(1.00)2(3.4)





k(la) = 6.59





k(-OH) = 0.036     (Table  1)





kOH = 6.59 + 0.036 =6.63






     (Estimated)  = 6.63  x  10~12cm^molecule~1s~3-





kOH  (Experimental) = 5.21  x  10"12cm3molecule~1s~1  (Table 6.A.)





Percent Error =  f (6.63-5.21)/5.21] (100)  = +27






IV.D.2.  1,2-ETHANEDIOL             HOCH2CH2OH





kOH = k(l) + k(2) = k(la)  +  2k(-OH)





k(la) = 2 k|F(-OH)F(-CH2-) = 2(0.838)(3.4)(1.29)





k(la) a 7.35





k(-OH) = 0.036   (Table  1)






kOH = 7'35 + 2(0.036) = 7.42





k0H  (Estimated)  = 7.42  x  10~12cin3Inoiecu^e-ls-l







                              -151-

-------
kOH (Experimental) =  7.7  x  10-12CB3molecule-ls-l  (Table 6.B.)

Percent Error  [  (7.42  -  7.7J/7.7] (100)  = -4

IV . E .  Ethers (Acyclic  and  Cyclic)

IV. E.I.  2-ETHOXYETHANOL

Using equation 20

kOH = k(l) + k(2) = k(la) + k(-OH)
k(la) = k,F(-CH2-0) + k|F(CH3-)F(-0-)
            + k|F(-CH2-)F(-0-)  +  k|F(-CH2-)F(-OH)

k(la) = 0.144(4.5) + 0.838(1.00) (6.1)
            + 0.838(1.29) (6.1)  +  0.838(1.29) (3.4)

k(la) = 16.03

k(-OH) = 0.036   (Table  1)

kOH = 16.03 + 0.04 = 16.07

     (Estimated)  = 16.1  x  10~12cm3molecule""1s~1

     (Experimental) = 15.4 x  10~12cm3molecule~1s~1   (Table 6.C.)

Percent Error =  [ (16.1-15.4) /is. 4] (100)  = +5
                              -152-

-------
IV. E. 2.  DIBTHOXYMETHANE       CH3CH2OCH2OCH2CH3






kOH = k(la) - 2k,F(-CH2-0-)  +  2kF(CH3-) F(-O-)
kOH = 2(0.144) (4.5) +  2(0.838(1.00) (6.1)  -I- 0. 838 (6. 1) (1. 0)





kOH = 16.6





kOH[ Estimated] =  16.6  x  10~12cm3molecule~1s~1





kOH[ Experimental] = 16.8  x  10~12cm3molecule~1s~1   (Table 6.C.)





                                      (100)  = -1
Percent Error =   (16.6 -  16.8)/16.8
IV.E.3.  1,2-EPOXYBUTANE                CH2CHCH2CH3
kOH = k(l) = k(la)  + k(lc)






Using equation 28  for  the  CH3CH2- group






k(la) = kF(-CH2-)  + kF(CH3-)F(>CH-)






k(la) = 0.144(1.29) +  0.838 (1.00)(1.29)  = 1.27






Using equation 43  for  the  three membered epoxide ring






k(lc) = [ k,F(-0-)F(>CH-) + kgF(-0-)F2(-CH2-)l F(3)







k(lc) =[ 0.838(6.1) (1.29)  +  1.83(6.1) (1.29)2 ](0. 017)







k(lc) = 0.43







                              -153-

-------
    = 1.27 + 0.43 = 1.70

kOH (Estimated) = 1.70 x 10~12cm3molecule"1s~1

k0H (Experimental) = 2.1 x 10~12cm3molecule~1s"1   (Table  6.D.)

Percent Error = [  (1.70-2.1)/2.1 ](100) = -19

IV.E.4.  OXEPANE  (HEXAMETHYLENE OXIDE)

                                                CH2	CH2


Using equation 43                               CH2CHf^

kOH = k(lc) = {2k|F(-CH2-)F(-0-) + 2k|F(-CH2-)F(-CH20-)
                           + 2k|F2(-CH2-)}F(7)

*OH = {2(0.838)(1.29)(6.1) + 2(0.838)(1.29)(4.5)
                           + 2(0.838)(1.29)2}(1.0)

kOH = 25.7

kOH[Estimated] =  25.7 x 10"12cm3molecule"1s~1

fcoH[ExPer^men^al] ~ !5'4 x 10~12cm3molecule"1s~1  [Table 6.D.]

Percent Error = I  (25.7-15.4)/15.4]  (100) = +67

IV.F.  Nitrates
IV.F.I.  3-METHYL-2-PBNTYL NITRATE            ON02
                                           CH3CHCHCH2CH3
                                                CH3

                             -154-

-------
kOH = k(l) = k(la) = kgF(>CH-ON02)  +  kgF(-ON02)F(CH3-)F(>CH-)
           + kgF(CH3-)F(-CH2-)F(>CHON02)
               + k,F(>CH-)  + k|F(CH3-)F(>CH-)  + k,F(-CH2-)

= 0.144(0.30) + 1.83(0.18)(1.00)(1.29)
      + 1.83(1.00) (1.29) (0.30)  +  0.144(1.29)
          + 0.838(1.00)(1.29)  + 0.144(1.29)

kOH = 2.63

kOH (Estimated) =  2.63  x  10~12cm3molecule~1s"1

k0H (Experimental) = 3.02  x 10~12cm3molecule~1s~1  (Table 7.A.)

Percent Error = f  (2.63-3.02)/3.02 1(100)  = -13

IV.G.  Nitriles

IV.G.1.  PROPIONITRILE                   CH3CH2CsN

kOH = k(l) = k(la) = kgF(-CH2CN)  + k|F(CH3-)F(-CN)

kOH = 0.144  (0.5)  + 0.838(1.00)(0.14)

kQH ~ 0.189

kOH (Estimated) =  0.189 x 10~12cm3molecule"1s~1

kOH (Experimental) = 0.194 x  10~12cm3molecule~1s~1
                                          (Table 7.C.)

Percent Error = [  (0.189-0.194)/O.194)] (100)  =  -3
                              -155-

-------
IV.H.  Unsubstituted Alkenes  (Acyclic and Cyclic)

IV.H.I.  l-PBHTENE       CH3CH2CH2CH=CH2

Using equation 20 yields

kOH = k(l) + k(3)

where k(l) represents the rate constant for hydrogen

abstraction from a C-H group and k(3) represents the rate of OH

radical addition to the >C=C< group.  The rate constant k(l) is

given by the equation

k(l) = k(la) + k(l,UNS CH)

Using equation 28 and the appropriate group rate constants and

substituent factors from Tables 1 and 2 yields

k(la) = kF(-CH2-) + ks(CH3-)F(-CH2-)
             + k|F(-CH2-)F(>C=C<)

k(la) = 0.144(1.29) + 0.838(1.00)(1.29) + 0.838(1.29)(1.0)

k(la) = 2.3

k(l,UNS CH) = O    (Table 1)

k(l) = 2.3 + 0 = 2.3

     Using equations 89, 90, and 91 and the appropriate group

rate constant and substituent factors from Tables 9 and 10,

respectively, yields

                = kis[RCH=CH2] [C(CH3CH2CH2-)]

                             -156-

-------
k(3) = 26.3(1.00) = 26.3





kOH = 2.3 + 26.3 = 28.6





    (Estimated) = 28.6 x 10~12cm3molecule"1s~1





kOH (Experimental) = 31.4 x 10~12cm3molecule~1s~1  (Table  13.A.)





Percent Error = [  (28.6-31.4)/31.4 ](100) - -9






IV.H.2.  1,4-PENTADIENE          CH2=CH-CH2-CH=CH2





kOH = k(l) + k(3)





k(l) = k(la) + 2k(l,UNS CH)






k(la) = k|F2(>C=C<) = 0.838(1.0)2 = 0.8





k(l,UNS CH) = 0





k(l) = 0.8 -I- 2(0) = 0.8





Using equations 89, 90, and 91 and the appropriate group  rate



constants and substituent factors from Tables 9 and  10,



respectively, yields






*add,nar = 2kos  [CH2=CH-R]  [C(-CH2-)] = 2(26.3)(1.00)





k(3) = kadd/nar = 52.6





kOH = 0.8 + 52.6 = 53.4





     (Estimated) = 53.4 x 10~12cm3molecule"1s~1






                              -157-

-------
kOH (Experimental) = 53.3 x  10-12cm3molecule-ls-l (Table 13.A.)


Percent Error = [  (53.4-53.3)/53.3 ](100)  = 0
IV.H.3.  BICYCLO[2.2.1]-2-HEPTENE
*OH = Ml) + *(3)
     = k(lc) + k(l,UNS CH)
k(lc) =
    kF2(>CH-) + 2k|F2(-CH2-)F(>C=C<)
             2 k|F(>CH-)F(-CH2-)
                            F2(5)F(6)
k(lc) =
     0.838(1.29)2 + 2(1.83)(1.29)2(1.0)

          +2(0.838)(1.29)2
                                              (0.80)2(1.0)
k(lc) = (10.3)(0.64) = 6.6
k(l,UNS CH) - 0
= 6.6
                 6.6
kadd,
       nar
                       RCH=CHR
                         cis
                           [C2(cycloalkyl)] =  56.1(1.00)2
k(3) = 56.1
                              -158-

-------
kOH = 6.6 + 56.1 = 62.7

kOH (Estimated) = 62.7 x 10~12cm3molecule~1s~1

kOH (Experimental) = 49.3 x  10~12cm3molecule~1s~1  (Table 13.B.)

Percent Error = [  (62.7-49.3)/49.3 ](100) =  +27

IV.I.  Substituted Alkenes

IV.I.I.  VINYL BROMIDE                      CH2=CHBr

^OH = ^ (1) + M 3)

k(l) = k(l,UNS CH) = 0

k(3) = kadd,nar - kis  [CH2=CH-R][C(Br-)]

k(3) = 26.3(0.26) = 6.84

kOH =  + 6.84 =  6.84

    (Estimated) = 6.84 x 10~12cm3molecule~1s~1

    (Experimental) = 6.81 x  10~12cm3molecule~1s~1  (Table 14)

Percent Error - [  (6.84-6.81)/6.81 1(100) =  0

IV.I.2.  trana-2-BUTENAL  (trans-CROTONALDEHYDE)
                                                 CH3     XH
                                                         N,
                                                         "CHO

kOH = k(l) + k(3)

                              -159-

-------
     ='k(la) + k(l,UNS CH)





k(la) = kg F(>C=C<) + kg F(0) F(>C=C<)





k(la) = 0.144(1.0) + 1.83(8.8) (1.0) =  16.2





k(l,UNS CH) - 0





k(l) = 16.2 + 0 = 16.2
k(3) = kadd/nar =
                         trans



                  63.7(1.00)(0.26)
[C(CH3-)]  [C(-CHO)]
k(3) - 16.6





kOH = 16.2 +16.6 = 32.8






    (Estimated) = 32.8 x 10"12cm3molecule~1s~1





kOH (Experimental) = 36 x  10~12cm3molecule~1s~1  (Table 14)





Percent Error = [  (32.8 - 36)/36 ](100) =  -9






IV.I.3.  cis-3-HEXENE-2,5-DIONB    fcis-1.2-DIACETYLETHYLENE]
                                                V
                                               =9
                                                CH-
 OH = k(l) + k(3)




     = k(la) + k(l,UNS CH)
                              -160-

-------
k(la) = 2kgF[-C(0)-]  = 2(0.144)(0.76) = 0.22


k(l,UNS CH) =  0


k(l) = 0.2 + 0 = 0.2
M3) = kadd/nar  =
kis (RCH=CH-R)
C2[CH3C(0)-]
                            CIS


k(3) = 56.1(0.91)2  = 46.5


kOH = 0.2 +  46.5  =46.7


kOH (Estimated) = 46.7 x 10~12cm3molecule~1s~1


kOjj (Experimental)  = 63.1 x 10~12cm3molecule~1s""1  (Table 14)


Percent Error  = [ (46.7-63.1)/63.1 ](100) =  -26


IV.I.4.  TETRACHLOROETHENE
                                         Cl    /Cl

                                         C1X   SC1


kOH = k(l) +  k(3)


k(i) = o


JV I J J ~" **a/^*^  n Sk 1* "" *rt  L **O **~^**O J- L  V^^J I
  * '    duu f ricirr     \j  ** &    J *   *    J


k(3) = 110(0.2)4  = 0.176


kOH = 0 + 0.176 = 0.176


kOH (Estimated) = 0.176 x 10~12cm3molecule""1s"1


                              -161-

-------
kOH  (Experimental) =  0.167  x  10-12cm3molecule-ls-l  (Table 14)






Percent Error = [  (0.176-0.167) /0. 167 1(100)  = +5






IV. I. 5.  ACRYLONITRILE                 CH2=CH-CsN





kOH = k(l) + k(3)





k(l) - k(l,UNS CH) =  0






k(3) " *add,nar = kis(CH2=CH-R) [C(-CN) ]





k(3) = 26.3(0.15)





k(3) = 3.95






kOH = 0 + 3.95 = 3.95





     (Estimated) = 3.95 x  10~12cm3molecule""1s~1





kOH  (Experimental) =  4.1  x  10"12cm3molecule~1s~1  (Table 14)





Percent error = [  (3.95-4.1) /4.1 ]  (100) =  -4






IV. I. 6.  METHYL KETENE





                                        CHCH=C=O
k(l) = k(la) + k(l, UNS CH)





k(la) = k,F(>C=C<) = 0.144  (1.0) =  o.l







                              -162-

-------
k(l, UNS CH) = 0






k(l) = 0.1 + 0 = 0.1






M3) = *add,nar = 4S(-CH=C<) [C(=0) ]





k(3) = 86.9  (1.0) - 86.9






kOH = 0.1 + 86.9 - 87.0






kOH[Estimated] = 87.0  x  10~12cm3molecule"1s~1






JcOHtExPer^mentalJ = 70 x  10""12cm3molecule~1s~1 [Table 14.B.]





Percent error =  [(87.0-70)/70]  (100)  - +24






IV.J.  Conjugated Diolefins






IV.J.I.  is-l,3-PBNTADIBNB





                                            V/>ij     /"*tJ
                                             v-ii    x  3



                                              HX   NH
kOH -




k(l) = k(la)  +  2  k(l,UNS CH)





k(la) - kgP(>O=C<)   = 0.144(1.00)  =0.1





k(l,UNS CH) = 0





k(l) = 0.1 +  2(0)  = 0.1
                              -163-

-------
Using the appropriate group rate constants  and substituent
factors from Tables 11 and 10, respectively,  yields
                = k(CH2=CH-CH=C-R)  [C(CH3-)]
         = 105(1.00) = 105
kOH - 0.1 + 105 = 105

    (Estimated) = 105 x 10~12cm3molecule~1s~1

kOH (Experimental) = 101 x 10"12cm3molecule"1s""1  (Table 15)

Percent error - [  (105-101) /101 ](100) = +4

IV . J . 2 .  1,3 -CYCLOHEXADIENE
                             H
kOH = k(l) + k(3)

     = k(lc) + 2k(l,UNS CH)
k(lc) = [ 2k|F(-CH2-)F(>C=C<)] F(6)

      = [ 2(0.838) (1.29) (1.0)] (1.00)


k(lc) = 2.2

k(l,UNS CH) = 0

k(l) = 2.2 + 2(0) = 2.2

                             -164-

-------
     = kadd,nar = kS[R-CH=CH-CH=CH-R]  [C2(-CH2-]





k(3) = 135(1.00)2  135





kOH - 2.2 + 135 = 137






kOH (Estimated) = 137 x 10~12cm3molecule~1s~1






kOH (Experimental) = 164 x  10~12cm3molecule~1s~1   (Table 15.B.)





Percent Error = [  (137-164)/164 ](100)  =  -16







IV.J.3.  2,5-DIMETHYL-2,4-HEXADIENE      (CH3)2C=CH-CH=C(CH3) 2





kOH - k(l) + k(3)





k(l) = k(la) + 2k(l/UNS CH)






k(la) = 2[2kF(>C=C<)] = 2(2)(0.144)(1.0)





k(la)  - 0.6





k(l,UNS CH) = 0





k(l) = 0.6 + 2(0) = 0.6






k(3) " kadd,nar = Jcg[RRC=CH-CH=CRR]  [C4(CH3-)]





k(3) = 230(1.OO)4 = 230





kOH = 0.6-1- 230 = 231





k0H  (Estimated) = 231 x I0~12cm3molecule~1s~1






                              -165-

-------
kOH (Experimental) = 210 x 10-12cm3molecule-ls-l   (Table 15. A.)





Percent Error - [  (231-210) /210 ](100) = +10






IV. J. 4.  4-METHYL-l,3-PENTADIENB              CH2=CH-CH=C(CH3) 2





kOH = k(l) + k(3)





     = k(la) + 2k(l,UNS CH)
k(la) = 2kF(>C=C<) = 2(0.144) (1.0) - 0.288






k(la) = 0.3






k(l,UNS CH) - 0






k(l) = 0.3 + 2(0) = 0.3






*(3) = *add,nar = k[CH2=CH-CH=CRR]  [C2(CH3-)] =  135(1. 00) 2





k(3) = 135






kOH = 0.3 + 135






kOH  (Estimated) = 135 x 10"12cm3molecule~1s"1






kOH  (Experimental) = 131 x 10~12cm3molecule~1s~1  (Table  15. A.)






Percent Error = [  (135-131) /131 ]  (100)  +3







IV. K.  Alkvnes






IV. K.I.  1-BUTYNB                     CH3CH2CsCH







                              -166-

-------
           + k(3)





       k(la) + k(l,UNS CH)






k(la) = kgF(-CH2-) + ksF(CH3-)F(-CsC-)





k(la) - 0.144(1.29) + 0.838(1.00) (1.0)





k(la) - 1.02





k(l/UNS CH) = 0





k(l) = 1.02 + 0 =  1.02





Using the appropriate group rate  constants and  substituent



factors from Tables 12 and 9, respectively, yields
k<3) - kadd,nar = *U(R-C*CH)  [C(CH3-)] =  6.4(1.00)





k(3) = 6.40





kOH = 1.02 + 6.40 = 7.42





kOH (Estimated) = 7.42 x  10"12cm3molecule~1s~1





k0H (Experimental) = 8.0  x  10~12cm3molecule~1s~1   (Table  16. A.)





Percent Error - [  (7.42-8.0) /8.0 ]  (100) =   -7
IV.L.  Allenes





IV.L.I.  1,2-PENTADIBNB                   CH2=C=CH-CH2CH3




                              -167-

-------
kOH = k(l) + k(3)





k(l) = k(la) + k(l,UNS CH)





k(la) = kF(-CH2-) + k,F(>C=C<)F(CH3-)





k(la) = 0.144(1.29) + 0.838(1.0) (1.00)





k(la) = 1.0





k(l,UNS CH) = 0





k(l) = 1.0 + 2(0) = 1.0





k(3) = kadd,nar = ku[RCH=C=CH2][C(CH3CH2-)]





Using the appropriate group rate constants  and substituent



factors from Tables 12 and 9, respectively, yields





k(3) = 31(1.00)





k(3) = 31.0





kOH = 1.0 + 31.0 = 32.0





kOH  (Estimated) = 32.0 x  10~12cm3molecule~1s~1





kOH  (Experimental) = 35.5 x 10~12cm3molecule~1s~1  (Table  16.B.)





Percent Error - f  (32.0-35.5)/35.5 ](100) = -10






IV.M.  Thiols. Sulfides.  and Disulfides





IV.M.I.  2-METHYL-l-PROPANETHIOL              (CH3)2CHCH2SH




                             -168-

-------
From equation 20

kOH = k(l) + k(4)
     - k(la) - 2kF(>CH-) + kF2 (CH3-)F(-CH2-)

              + kgF(>CH-)F(-SH)


k(l) = 2(0.144) (1.29) +  1.83(1.00)2(1.29)  +  0. 838 (1. 29) (9 . 0)


k(l) - 12.5


k(5) = k(-SH) = 31  (Table 1)


kOH = 12.5 + 31 = 43.5


kOH (Estimated) = 43.5 x 10~12cm3molecule~1s"1


kOH (Experimental)  = 45  x 10~12cm3molecule~1s~1  (Table 18. A.)


Percent Error - [  (43.5 - 45) /45 ] (100)  = -3
IV.M.2.  TETRAHYDROTHIOPHENE
                                                 CH2	CH2
                                                 ,2    ,2
                                                 CH2    CH2
Calculation of kQH  in the  absence  of  02            >>s
    = Ml) + M4)

     - k(lc) -   [2kgF2(-CH2-)  -I-  2kgF(-CH2-)F(-S-)3F(5)


k(l) = [2(0.838)(1.29)2  +  2(0.838)(1.29)(9.0)](0.80)


k(l) - 17.8



                              -169-

-------
k(5) - k(-S-) = 0   (Table 1)

kOH = 17.8 + 0  17.8

kOH (Estimated) - 17.8 x 10~12cm3molecule~1s~1

kOH (Experimental) = 19.7 x 10~  cm3molecule~1s~1
                                   (Table  18. B. 2.)

Percent Error - [  (17. 8-19. 7) /19. 7 ](100) - -10

IV. M. 3.  DIMETHYL DISULFIDE                 CH3-S-S-CH3

kOH = k(l) + k(4)

k(l) = k(la) - 2k,F(-S-S-) = 2 (0.144) (9.0)

k(l) = 2.59

k(5) = k(-S-S-) - 200  (Table 1)

kOH = 2.6 + 200 = 203

kOH (Estimated) - 203 x 10~12cm3molecule~1s"1

k0u (Experimental) = 211 x 10~12cm3molecule~1s~1  (Table  18. C.)

Percent Error =( (203-211) /2li ](100) = -4

IV. H.   Compounds Containing Nitrogen Functional Groups

IV . N . 1 .  DIMETHYLHYDROXYETHYLAMINE           ( CH3 ) 2NCH2 CH2OH
                              -170-

-------
     = k(la) = 2kF(>N-) + kF(>N-)F(-CH2-)



                      + kjF(-CH2-)F(-OH)





k(l) = 2(0.144)(10) + 0.838(10)(1.29)  + 0.838(1.29)(3.4)





k(l) = 17.4





k(2) = k(-OH) = 0.036 (Table  1)





k(4) = k(>N-) = 60  (Table 1)





kOH = 17.4 + 0.04 + 60 = 77.4





kOH (Estimated) = 77.4 x 10~2cm3molecule"1s"1





kOH (Experimental) = 90 x 10~12cm3molecule~1s~1 (Table 19.A.)





Percent Error = [  (77.4-90)/90 ](100)  =  -14






IV.N.2.  DIMETHYL-N-NITROSAMINE         (CH3)2N-NO





kOH = k(l) + k(5)





k(l) = k(la) = 2kF(>N-NO)   2(0.144)(10)





k(l) = 2.88





k(4) = k(>M-NO) = 0   (Table 1)





kOH = 2.88 + 0 - 2.88





kOH (Estimated) = 2.88 x 10~12cm3molecule~1s~1
                              -171-

-------
    (Experimental) =  2.53 x  10-12  Cm3molecule~1s~1
                                         (Table 19. c.)

Percent Error = [  (2.88-2.53) /2. 53  ] (100)  - +14

IV. N. 3.  METHYL HYDRAZINB                 CH3NHNH2

koH = k(l) + k(5)

k(l) = k(la) = kgF(>NH) - 0.144(10)  = 1.44

k(4) = k(CH3NH-)  + k(-NH2)

k(4) =60+20  (Table 1)

k(4) = 80

JCQH = 1.4 + 80 -  81.4

kOH (Estimated) = 81.4 x 10-12cm3molecule-1s-1

koH (Experimental) -  65 x 10"12  ^molecule'^-s'1 (Table 19. E.)

Percent Error - f  (81. 4-65) /65 ](100)  - +25

IV. N . 4 .  DIBTHYL-N-HYDROXYLAMINE             ( CH3CH2 ) 2N-OH
     = k(la) - 2[ kpF(-CH2-)  + kgF(CH3-)F(>NOH)

k(l) = 2[0. 144(1. 29) +  0.838(1.00) (10) ]  - 17.14
                              -172-

-------
k(2) = 0.036   (Table 1)





k(4) = k(>H-) - 60   (Table 1)





    a 17.14 + 0.04 + 60 = 77.2






    (Estimated) = 77.2 x 10"12 cm3molecule"1s"1






kOH (Experimental) * 101 x 10~12 cm3molecule~1s~1 (Table 19.B.)





Percent Error = [  (77.2 - 101)/101 ]  (100)  =  -24






IV.O.  Compounds Containing Phosphorus  Functional Groups





IV.0.1.  TRIETHYL PHOSPHATE                (CH3CH2O)3P=O





kOH = k(l) + k(6)





k(l) = k(la) = 3[k,F(-CH2-0-) + k,F(CH3-)F(O-P<) ]





k(l) a 3[0.144(4.5) -I- 0.838(1.00) (20)]





k(l) = 52.2





k(6) = k[P(0)] -  0   (Table 1)






koH = 52.2 + 0 =  52.2





kOH (Estimated) = 52.2 x 10"12cm3molecule~1s~1





kOH (Experimental) = 55.3 x 10"12cm3molecule~1s"1 (Table 20.A.)





Percent Error = [  (52.2-55.3J/55.3 1(100)  = -6









                              -173-

-------
IV.0.2  O,O-DIMBTHYL CHLOROPHO8PHOROTHIOATB



                                                        S
                                                        II
                                                 (CH30)2P-C1



kOH = k(l) + k(6)



k(l) = k(la) = 2[kpF(-0-P<)] =  2(0.144)(20)



k(l) - 5.76



k(6) - k[P(S)] + k[P-Cl]



k(6) =55+0  (Table  1)



k(6) =55



kOH = 5.8 + 55 = 60.8



)CQH (Estimated) = 60.8 x  10~12cm3molecule~1s~1



JCQJI (Experimental) = 59.0 x  10"12cm3molecule~1s~1  (Table 20.B.)



Percent Error = [ (60.8-59.0)/59.0 1(100)  =  +3



IV.0.3  0,O,H-TRIMBTHYL PH08PHOROAMIDOTHIOATE
                                                        S

                                                 (CH30)2P-NH-CH3
       k(la) = 2[kg(-0-P<)]  +  kgF(>NH)
                              -174-

-------
k(l) = 2(0.144)(20) + 0.144(10)





k(l) - 7.2





k(4) = k(>NH) = 60  (Table  1)





k(6) - k[P(S)] - 55 (Table  1)





kOH - 7.2 + 60 + 55 - 122





    (Estimated) - 122 x  10~12cm3molecule~1s~1






kOH (Experimental) = 233 x  10"12cm3molecule~1s~1 (Table 20.C.)





Percent Error - [ (122-233)/233 ](100)  = -48






IV.P.  Aromatic Compounds





IV.P.I.  TOLUENE
Using equation 20





k(OH) = k(l) + k(7) = k(l)  + kadd/ar






k(l) = k(la) - k(l,UNS CH)





k(l) = kgF(-C6H5) = 0.144(1.0)  =  0.14





k(l, UNS CH) - 0






                             -175-

-------
k(l) = 0.14 + 0 - 0.14

Using equations 127 and 128 and the appropriate values  of  a+

from Table 22
logic* add,ar * -31 ' 1-35
a+(CH3-) = -0.066 ; a+(CH3-) - -0.311   (Table 22)

From rule 2, page 112   a(CH3-) = a(CH3-) - -0.311

From the molecular  structure shown above and symmetry

                  = aJ(CH3-) -  -0.311
                  =, a+(CH3-) =  -0.066
           a+(CH3-)  - -0.311

Using the most negative value of  
-------
IV.P.2.  trans-1-PHENYL-l-PROPENE
                           H(l)
kOH =
k(3) + k(7) =
                                  H(2)
                                  k(3)
     = k(la) + 2k(l,UNS CH)
k(la) = kpF(>C=C<)  0.144(1.0) = 0.14



k(l,UNS CH) = 0



k(l) = 0.14 -f 2(0) = 0.14



As proposed by Atkinson  (1987) , it is assumed that there  is  no

interaction between the  two carbon-carbon double bond systems

so that the OH radical adds separately to the alkene group and

the benzene ring.  Using equations 90 and 91



     = kadd,nar =
k(3) = kis  [RCH=CHR ]  [C(CH3-)c(c6H5-)]
            1         J
              trans
k(3) = 63.7(1.00) (1.00) = 63.7   (Tables 9 and  10)
From Table 22
ajj(CH2=CH-) =0.02
                              -177-

-------
a+(CH2=CH-) = aJ(CH2=CH-) =0.02



From the molecular structure shown above and symmetry  for the

benzene ring
                              -) =0.02
=  +
        = <7(CH2=CH-)  =0.02



        = 53a+(4)  = a+(CH2=CH-) = 0.02 (most negative)



    *add,ar = -31 - 1.35(0.02)



* add , ar =  1 . 9



kOH = 0.1 + 63.7 4- 1.9 = 65.7



kOH (Estimated) = 65.7 x I0~12cm3molecule~1s~1



k0H (Experimental) = 59 x 10~12cm3molecule~1s~1   [Table  23. C.]



Percent Error = [ (65.7-59)/59 ]  (100) = +11



IV . P . 3 .  4 -CHLOROBBNZOTRIFLUORIDB

                                  Cl

                           H(3) i
                                o
                                  r"
                                  CF3

kOH = *(l) + k(?) = k(1) + k'add,ar


                             -178-

-------
k(l) = k(l,UNS CH) = 0

a+(Cl-) - 0.399               a+(CF3-) = 0.52

a+(Cl-) = aJ(Cl-) = 0.114     a+(CF3-) - aJ(CF3-) =  0.612

From the above molecular structure and symmetry

                                      )  = 0.612 + 0.399 = 1.011
                           )  + a+(CF3-) = 0.114 + 0.52 = 0.634
                                                 (most  negative)

I9l0kadd,ar = -31 - 1-35(0.634)

kadd,ar = -285

kOH =  +0.285 = 0.285

kOH (Estimated) = 0.285 x  10~12cm3molecule"1s~1

kOH (Experimental)  =  0.24  x  10~12cm3molecule~1s~1  (Table 23. E.)

Percent Error = [  (0.285-0.24) /0. 24 ](100)  +19

IV. P. 4.   1,2,4-TRICHLOROBENZENE
                                   Cl
 OH = k(l) + k(7) = k(l) + k'add/ar
                              -179-

-------
k(l) = k(l,UNS CH) = 0

aJ(Cl-) = 0.399; aJ(Cl-)  a+(Cl-) =  0.114

From the molecular structure

        = 2a+(Cl-) + aJ(Cl-)  =2(0.114)  + 0.399 = 0.627

        = aJ(Cl-)  -I- a+(Cl-)  + aJ(Cl-) = 2(0.114)  + 0.399

        = 0.627  (most negative)

CT+(3) = a+(Cl-)  -I- 2ffJ(Cl-)  = 0.114  + 2(0.399) = 0.912

Iog10 *-add/ar = 0.31  -  1.35  (0.627)

k'add,ar = -291

kOH =  + 0-291 = 0.291

kOH (Estimated) = 0.291 x 10~12cm3molecule~1s"1

kOH (Experimental) = 0.532 x  10~12cm3molecule~1s~1
                                               (Table  23.D.)

Percent Error - [  (0.291-0.532)/0.532  ](100) =  -45
                             -180-

-------
IV.P.5.  o-CRESOL



                                    OH
                                    H(2)





kOH = k(l) + k(2) + k(7)  =  k(l)  + k(2)  + k'add/ar





k(l) = k(la) + k(l,UNS  CH)





k(la) - kF(C6H5-) =  0.144(1.0)  = 0.144





k(l,UNS CH) = 0





k(l) = 0.14 + 0 = 0.14





k(2) = k(-OH) = 0.036





        = 0.121                     a+(CH3-)  = -0.066





        = -0.92                     a+(CH3-)  = -0.311





        = a'I'(-OH) = -0.92         ffj"(CH3-)  = a+(CH3-) = -0.311
 ^         ft                        ^J          ^J      '




From the molecular structure shown above





                      r+f-
         = a+(CH3-)  + a(~OH) = -0.311 + 0.121 = -0.190




Va+(2)  = a+(CH3-)  + <7p(-OH) = -0.066 - 0.92 = -0.986





a+(3)  - aJ(-OH)  + a+(CH3-) =  ^a+(D =  -0.190
                              -181-

-------
                                         = -0.986
                                           (most  negative)
l9lokadd,ar = *31 " i-35^0

kadd,ar = 43.8

kOH = 0.14 + 0.04 + 43.8 = 44.0

KQH (Estimated) = 44.0 x 10""12cm3molecule~1s"1

kOH (Experimental) = 42 x 10-12cm3molecule-1s~1  (Table 23. G.)

Percent Error =  [(44.0-42) /42] (100) = +5

IV. P. 6.  ANILINE
                                   H(3)

kOH = k(l) + k(5) + k(7) = k(l) + k(5)

k(l) = k(l,UNS CH) - 0

k(5) = k(-NH2) - 20  (Table 1)

           -0.16
                                   (Table 22)
                      -1.3
                             -182-

-------
From the above molecular structure and symmetry





                              = -1.3





                     aJ(-NH2) = -0.16





        = a +  (-NH2)  = -1.3      (most negative)





I9l0kadd,ar " -31 ~ l-35(-1.3)
kOH = 0 + 20 + 116 = 136





k0jj (Estimated) = 136 x 10~12 cm3molecule"1s~1





kOH (Experimental) = 111 x 10~12cm3molecule~1s~1   (Table 23.1.)





Percent Error = [  (136-111) /111 ](100) = +23






IV . P . 7 .  HEXAFLUOROBENZENE
kOH = k(l) + k(7) = k(l) -f kadd/ar





k(l) = k(l,UNS CH) = 0





      = 0.352; ^J(F-) = ffJ(F-) =  -0.073






                              -183-

-------
From symmetry and the above molecular  structure
For a completely substituted benzene,  all  the  positions are
considered.  Therefore, for    a+(l)  we have
                           Position No.
           (1)      (2)      (3)      (4)      (5)      (6)

E+'
                    o        m        p   '     m        o
Using rule 5, p. 113, the ipso position  is the (1)  position so
that a+(l) = a+(F-).  Therefore

        = *i(F-) + ffJ(F-) + ^J(F-)  + ^(F-)  + ffJ(F-) + aJ(F-)

        - 3aJ(F-)  + 2aJ(F-)  + aJ(F-)

        = 3(0.352)  + 2(-0.073)  + (-0.073)  =  0.837

Furthermore,

             a+(2)  = \^a"l"(3)  = 5^cr"l"(4)  = Y^a+(5) = T^a+(6)  = 0.837

Since this is the  only value,  it  is the  most  negative value;

Iogi0kadd,ar = -31 " 1-35(0.837)

^ add,ar = u'15^
kOH = 0 +  0.151 =  0.151

kOH (Estimated) =  0.151 x 10~12cm3molecule~1s~1

                              -184-

-------
kOH (Experimental) = 0.172 x  10-l2cm3molecule-ls-l
                                          (Table  23. D.)
Percent Error - [  (0.151-0.172) /0. 172 ](100)   -12
IV.P.8.  2,3-DIHYDROBENZOFURAN
                                   H(4)
OH
             k(7)
                         + k'add/ar
     = k(lc) + k(l,UNS CH)
For the five-membered heterocyclic  ring
k(lc) = [kF(-CH2-0-)F(C6H5-) + kF(-CH2-)F(-0-)]F(5)
k(lc) =  [0.838(4.5)(1.0)  +  0.838(1.29)(6.1)](0.80)
k(lc) = 8.3
k(l,UNS CH) = 0
k(l) = 8.3 + 0 = 8.3
ffm(~CH2") = -0.064
                                   a+(-0-) = 0.047
ff(-CH2-) = aJ(-CH2-) = -0.295
                                    a+(-O-)  = a+(-0-)  = -0.778
        = aJ(-CH2-)
                          -O-)  = -0.295 + 0.047 = -0.248
                              -185-

-------
             (-CH2-)  + ff(-O-)  = -0.064 - 0.778 = -0.842

$>+(3)  = a^(-O-)  + cr(-CH2-)  = J>+(1) = -0.248
                                          = -0.842
                                             (most negative)

                -31 - 1.35(-0.842)


kadd,ar = 28.0


kOH =8. 3+ 28.0=  36. 3


    (Estimated) = 36.3 x  10-12cm3molecule~"1s-1


kOH (Experimental)  =  36.6 x  10~12cm3molecule-1s-1 (Table 23. J.)


Percent Error = [  (36.3-36.6) /36. 6  1(100)  =  -1



IV . P . 9 .  3 -CHLOROBIPHENYL
                                  Ring A      Ring B


kOH = k(l) + k'addfar(Ring A)  + k-add,ar(Ring  B)


k(l) = 2k(l,UNS CH) =2(0) =0  for both rings
                              -186-

-------
For Ring A
 +-
a(-C6H4Cl) = 0.25
a+(-C6H4Cl)
                          =0.02
From Symmetry
          J>+(5)  = aJ(-C6H4Cl) = 0.02
$>+(2) o a+(4)  = a+(-C6H4Cl) = 0.25
J)a+(3) = a+(-C6H4Cl)  =
                                    0.02    (most negative)
Iog10k'add/ar (Ring A)  = 0.31 - 1.35(0.02)
kadd,ar (Rin? A)  " i-
For Ring B
                            H(2)
                                   Cl
                                        ") =  0.399
                             -187-

-------
a+(C6H5-) = aJ(C6H5-) =  -0.179      aJ(Cl-)  = a+(Cl-)  = 0.114


                   )  + a(Cl-)  = -0.179 + 0.114 = -0.065

            J(Cl-)  + ffJ(C6H5-)  = J>+(1) = -0.065



                             )  = '109 + 0.399 = 0.508
J>+(4) =  a+(C6H5-)  + aJ(Cl-)  = ^a+(l) = -0.065
                        *                  (most negative)
                   B)  - 0.31 - 1.35(-0.065)


kadd,ar(Rin
-------
k(l) = 0.1 + 2(0) = 0.1

Using equation 138 for OH radical addition  to  the aromatic ring

lo
-------
IV . P . 1 1 .  1,4 -DICHLORONAPHTHALENE
 OH
kOH
             K(8)
           -I- k
               add,PAH
k(l) = k(l, UNS CH) = 0
IP = 8.13 eV for naphthalene  [Weast  (1976  - 1977)]
       Cl
            H(l)
            H(2)
       Cl
                         From Table  22
                              -) = ap-(Cl-)  = 0.114
                              -) = 0.399
                                    -) = 0.513
                             =  0.513  (most negative)
    k'add,PAH = 10-H " 1.08(8.13) - 1.35(0.513)
k'add,PAH
          = 4-37
kOH = 0 + 4.37 = 4.37
kOH [Estimated] = 4.37 x  10~l2cm3molecule~ls~l
k0H [Experimental] = 5.8 x  10""l2cm3molecule~ls~l  (Table 24)

Percent Error = [  (4.37-5.8)/5.8] (100) -  -25

V.  Tropospheric Half-Life
     The half-life in the troposphere, t(i/2)E'  *-s 9iven bV
equation 7 which  is

                              -190-

-------
             t(l/2)E  " 0.693/kOH(OH)                    (141)
where k0n is the instantaneous rate constant for the reaction
of an organic chemical with hydroxyl radicals in the units
cm3molecule"1s~1 and (OH) is the hydroxyl radical concentration
in the units molecules (or radicals) cm"3.  Equation 141
represents an instantaneous half-life.  However, in the
troposphere, (OH) represents an average concentration which is
a function of a number of variables such as season, time-of-
day, temperature, altitude, and geographical location.  To use
equation 141, an average OH concentration (OH) over these
variables is needed.
     Based on the modeling work of Crutzen  (1982), Atkinson
(1986) recommended that the seasonally and diurnally averaged
hydroxyl radical concentrations at 298 K should be:
       5  x 105  molecules  cm"3  in the northern hemisphere;
       6  x 10^  molecules  cm"3  in the southern hemisphere.
     Prinn et al.  (1987) made a recent estimate of the average
global OH concentration using the latest kinetic data on the
disappearance of methylchloroform [CH3CC13].  These researchers
used 7 years of analytical data on the concentration of
methylchloroform in the troposphere  (approximately 60,000
measurements).  Because the reaction of hydroxyl radicals is
known to be a major loss for atmospheric methylchloroform,
these scientists were able to deduce the concentration of OH
radicals by combining measured trends in the methylchloroform
                             -191-

-------
levels in the troposphere with the industrial emissions of that
chemical.  Based on the data of Prinn et al. (1987), Atkinson
[in Arey et al. (1989) and Atkinson et al.  (1990)]  estimated
that the diurnally and annually averaged 12-h daylight hydroxyl
radical concentration is

         (OH) = 1.5 x 106 molecules(radicals)cm"3          (142)

         Atkinson  [in Arey et al.  (1989)] measured  the diurnal
concentrations of 8 volatile polycyclic aromatic hydrocarbons
(naphthalene, 1- and 2-methylnaphthalene, acenaphthylene,
biphenyl, acenaphthene, fluorene, and phenanthrene) with 12-h
daytime and 12-h nighttime sampling intervals over  a 9-day
period in August 1986 at Glendora, California.  Based on these
ambient concentrations and the known second-order rate
constants for the reaction of these polyaromatic compounds with
hydroxyl radicals, the average ambient hydroxyl radical
concentration was found to be 2.2 x 106 molecules-cm"3 which
agreed reasonably well with the average hydroxyl radical
concentration given in equation 142.
     Using the(OH)radical concentration defined in  142 as the
best seasonal and diurnal value at 298 K in equation 141 yields
   t(1/2)E(s) - 	^613_	
                I fcoH(cm''*mo^ecu^e~ls~1)j  ( OH (molecules cm"3)]

t(l/2)E(d> "
	^	0.693	
 kOH(cm;imolecule";Ls~1)] [ 4.32 x lO^sd"1] [ 1.5 x 105molecules cnT
                              -192-

-------
                	10.7  X  10~12   	                  (143)
                koufcm^moiecuie^s'1)]

Thus, with the value of k0g in cm-^molecule^s'1, either measured
experimentally or estimated by S/R methods at 298 K, the
tropospheric half-life (in a 12-h daylight day) can be estimated
using equation 143.  Since the average temperature in the
troposphere is less than 298 K, the use of k0H at 298 K will
introduce some error in the estimation of t(i/2)E*  Furthermore,
for chemicals in the troposphere with t^^JE ^ 1 daY (ie.,
with t/2/2)E which is short relative to the mixing time in the
troposphere) the use of an average OH concentration will lead to
an additional error.  Hence, t(i/2)E represents an approximate
value, especially when t/T/2\E ^ ! day.
VI.  Screening-Level Test Guideline:  Estimation of KOH and
     t(l/2)E for a Chemical  (S) Produced by Chemical Company X
     via the Estimation Techniques of Atkinson

     In order to illustrate the use of the S/R relationships
developed by Atkinson for estimating kQH and t/i/2\E under
Section 4 of TSCA, the following hypothetical scenario is
postulated.  Chemical Company X manufactures a wide range of
dyes for the textile, carpet, paper, and photographic
industries.  This chemical company is currently manufacturing a
solvent 2,3-difluoro-4-[l-methylpropyl]nitrobenzene (S) for  use
in the manufacture of a number of disperse dyes used in the
textile and carpet industries.
                              -193-

-------
     The manufacturing plant is located at 32.5 N. latitude  in
the northwest corner of Louisiana on Cross Lake, just west of
Shreveport.  The plant manufactures 2 million kg of S per year
which is used as an "on-site" solvent.  This chemical is
manufactured and used continuously throughout the year except
for two weeks at the end of December when the plant is closed
for maintenance and repairs.
     The plant contains primary and secondary treatment
facilities; the solid and solvent wastes are incinerated while
the aqueous wastes are discharged into Cross Lake.  Because the
plant is operated at relatively high temperatures and is not
"completely closed", chemical S vapors escape into the
atmosphere during manufacturing and use of the solvent.
     Since S volatilizes to the troposphere, it is important to
determine the chemical fate of this chemical in this
environmental compartment.6  Thus, screening-level tests in the
hierarchal test scheme developed by Leifer [USEPA (1989a)] will
be used as the first step in determining the chemical fate of S
in the troposphere.  Since the chemical can react with hydroxyl
radicals, the S/R relationships of Atkinson will be used to
estimate )CQJJ and t(i/2)E*
     Chemical S has the following molecular structure
6 It should be noted that S is also discharged into Cross Lake
  so that the environmental fate in aquatic media would also
  be needed.  However,  for the purposes of this report, the
  environmental fate in freshwater media will'not be considered,
                              -194-

-------
                    CH3CHCH2CH3
                                                           (144)
                              H(2)
                        1
                       N02



  Using equation 20,



                        kOH = k(l) + k(7)                  (145)



where:  k(l) represents the rate constant for H-atom  abstraction

from the secondary butyl group and from the aromatic  ring  by  OH

radicals; and k(7) represents the OH- radical addition to the

aromatic ring.

     The rate constant k(l) is given by the relationship



                 k(l) = k(la) + k(l,UNS CH)                (146)



Using equation 28 and the appropriate group rate  constants and

substituent factors  listed in Tables 1 and 2, k(l)  can be

calculated as follows:
k(la) = k,F(>CH-) +

         + k|F(CH3-)F(>CH-) + kF(-CH2-)                   (147)



For the purposes of this calculation,  it  is  assumed  that

F(C6H2F2N02-) = 1.0.



          k(la) = 0.144(1.29) +  1.83(1.00) (1.0) (1.29)

                -I- 0.838(1.00) (1.29) + 0.144(1.29)
                              -195-

-------
                          k(la) - 3.82                     (148)





Since H-atom abstraction from a benzene ring does not occur,



even at elevated temperatures, it is safe to assume that C-H



abstraction from (C6H2F2NO2-) in S at 298 K will also be



negligible.  Hence,





                        k(l,UNS CH)  = 0





                     k(l) = 3.82 + 0 - 3.82





                           k(l) = 3.82                     (149)





     Using equation 18 for the addition of OH radicals to  the



benzene ring, one obtains
                          = kadd,ar





and using equations 127 and 128 yields






                Igi0kadd,ar  = *31 " 1*35





where                kadd,ar  = lol2kadd,ar                <152)





     Using equation 151 and the molecular  structure of S



depicted in 144, k' ,,     can  be calculated as follows:
  c                add , ar


Using the rules on pages 107 and 113 and the appropriate



electrophilic substituent constants a+





 <7m(-CH<) = -0.060   <7+(F-) =  0.352      <7m(N02-)  = 0.674





            -0.280   ^p(F-) =  -0.073     a^(N02-)  = 0.790





                              -196-

-------
obtained from Table 22 gives


        = a+(-CH<) + a+(F-)  +  a(F-)  + a+(N02-)           (153)

        = -0.280 + 0.352 + (-0.073) +  0.674 = 0.673       (154)

        = a+(N02-) + ai(F-)  +  a+(F-)  + a^(-CH<)           (155)

        = 0.790 + 0.352 + (-0.073) +  (-0.060) = 1.01       (156)
Comparing the values of ^a(l) and ^a(2) given in 154 and

156, it is evident that  J^a+(l) represents the most negative

value so that k'  ,     can be calculated using equation 151 as

follows:


                Io9 k'add,ar  = -31  -  1-35(0.673)

                        kadd,ar = -252                  d57)


     Using the results from  149 and 157  in equation 145 gives


                  kOH = 3.82  + 0.252 =4.07


and multiplying this result  by the factor 10~12 yields


        kOH  (Estimated) = 4.07 x 10~12cm3molecule"1s""1    (158)


and substituting the result  of equation  158 in equation 143

yields
                         10.7 x 10~12
           t(l/2)E(d) =  -                      (159)
                         4.07 X 10~12
           t(l/2)E = 2-6 d  ^in 12~n daylight days)        (160)
                              -197-

-------
     For the purposes  of  this  report,  let  us  assume that direct

photoreaction  and  reaction with  ozone  are  negligible for

chemical S  (i.e.,  k^g  = kg-  -  0).   Since kgjj  (Estimated)  is

equal to 4.07  x  10"~12  cm3molecule"1s"1, OH radical  reaction with

S is the dominant  transformation mode  in the  troposphere.

Therefore,  an  upper-tier  test  guideline shall be  used to

determine kOH  .  Consequently, Test Guideline  796.3950 {Leifer

[USEPA  (1989a)}  shall  be  carried out using the relative rate

technique in a Teflon  bag to measure kOH for  S.


VII.  Mathematical Synopsis  of the  Structure/Reactivity
      Relationships of Atkinson

     Atkinson  (1986, 1986a,  1987, 1987b, 1988, 1988a),  based on

a detailed  analysis of the rate  data for the  reaction of

hydroxyl radicals  (OH) with  organic chemicals in  the gas-phase,

postulated  that  the overall  second-order rate constant (k0jj,

cm3molecule~1s~1)  at 298  K is  given by the mathematical

relationship

                            8
                      kOH  * E  *<*)                       (161)
where k(i) represents the second-order rate constant for  pathway
                                                8
(i) in the units cm3molecule~1s~1 at 298 K and  ,  represents
                                               i = 1
the summation over 8 possible reaction pathways.


Pathway 1:  H-atom abstraction from acyclic and cyclic
            saturated and unsaturated C-H groups by OH
            radicals

     The overall rate constant for reaction pathway 1 is given

by the equation

                             -198-

-------
         Jc(l) = k(la) + k(lc) + k(l, UNS CH)               (162)


where k(la) represents the rate constant for H-atom  abstraction

from all acyclic saturated C-H groups by OH radicals at 298 K;

k(lc) represents the rate constant  for H-atom  abstraction from

all cyclic saturated C-H groups by  OH radicals at  298 K;  and

k(l, UNS CH) represents the rate constant  for  H-atom

abstraction from all unsaturated C-H groups  (e.g.,=c-H)  by OH

radicals at 298 K.

     The rate constant k(la)  is given by the mathematical

relationship
         k(la)  =    kFi(X)  +   kiFj(X)Fj(Y)
                               j(a)                         (163)

                          *?Fm(X)Fm(Y)Fm(Z)
                                                   F(n)     (164)
                      m(a)
k(lc) =  kgFjWFjfY) +     k?Fm(X)Fm(Y)Fm(Z)
                            m(c)
                        k(l,  UNS  CH)  =  0                   (165)


where kS, k., k^ represent  the  group  rate constants for primary

(CH3-) , secondary  (>CH2) , and tertiary  (>CH-)  groups,

respectively, and  the  values  for  these  parameters are  listed in

Table 1 at  298  K;    ,     ,     ,    E  '  E  ' represent
                  i(a)    j(a)    m(a)     j(c)   m(c)
the summation  over  all  primary acyclic,  secondary acyclic,

tertiary  acyclic, secondary and tertiary cyclic groups,

respectively,  in the  molecule; F(X),  F(Y) ,  F(Z)  represent the

substituent  factors for substituents  X,  Y,  and Z and the values

for various  substituents are listed in Table 2 at 298 K; F(n)

                              -199-

-------
represents the ring strain factor for saturated and unsaturated
rings and heterocyclic rings containing n (3,4,5)  atoms at
298 K and the values are listed in Table 2.   For rings with
n(6,7,8, etc.), with essentially no ring strain, F(n)  1.0 at
298 K.
Pathway 2t  H-Atom abstraction from -0-H groups by OH radicals
     The overall rate constant for reaction pathway 2 is given
by the equation

                  k(2) = n(-O-H) k(-OH)                   (166)

where n(-O-H) represents the number of hydroxyl groups (-0-H)
in the molecule; k(-OH) represents the group rate constant for
H-atom abstraction from the hydroxyl group and is equal to
0.036 x 10~12cm3molecule~1s~1 at 298 K (Table 1).

Pathway 3;  OH radical addition to isolated alkene groups
             (>C=C<), nonaromatic conjugated groups
             (>C=C-C=C<), and other unsaturated groups
             (-CSG-, >c=c=c<, >oc=o)
     The overall rate constant for reaction pathway 3 is given
by the equation

     = kadd,nar
                                                          (167)
                     +E
                       m
where k^s, k, kgu represent the group rate constants for OH
radical addition  (add) to isolated (is) carbon-carbon double
bonds, nonaromatic  (nar) conjugated (co) carbon-carbon bond
                             -200-

-------
systems, and other unsaturated  (ou)  carbon-carbon  systems,

respectively,  and the  values  of  these  group  rate constants  are

given  in Tables  9, 11,  and  12, respectively,  at 298  K;  ) /   '
                                                        1   1
2s, represent the summation over all isolated carbon-carbon
m
double bond systems, nonaromatic conjugated  carbon-carbon

double bond systems, and other unsaturated carbon-carbon

groups, respectively,  in the  molecule;  C(X),  C(Y)  represent the

substituent factors  at 298  K  for substituents X and  Y,  Table

10.


Pathway 4;  OH radical interaction with -SH,  -S-,  and -S-S-
            groups

     The overall rate  constant  for reaction  pathway  4 is  given

by the equation


k(4) = n(-SH)k(-SH)  +  n(-S-)k(-S-)  + n(-S-S-)k(-S-S-)     (168)


where  n(-SH) ,  n(-S-) ,  and n(-S-S-)  represent the number of  -SH,

-S-, and -S-S- groups, respectively, in the  molecule; k(-SH) ,

k(-S-) , k(-S-S-) represent the  group rate constants  for OH

radical interaction  with the  -SH, -S-,  and -S-S- groups,

respectively,  and  the  values  of  these group  rate constants  are

listed in  Table  1  at 298 K.

Pathway 5:  OH radical interaction with -NH2, >NH, and >N-
            groups

     The overall rate  constant  for reaction  pathway  5 is  given

by the equation
 k(5)  = n(-NH2)k(-NH2)  + n(>NH)k(>NH)  + n(>N-)k(>N-)        (169)
                              -201-

-------
where n(-NH2), n(>NH), n(>N-) represent the number of -NH2/
>NH, and >N- groups, respectively, in the molecule; k(-NH2),
k(>NH), Jc(>N-) represent the group rate constants for -NH2,
>NH, and >N-, respectively, and the values of these group rate
constants are listed in Table 1 at 298 K.

Pathway 6;  OH radical interaction with phosphorous groups

     The overall rate constant for reaction pathway 6 is given
by the equation
k(6) = n
where n[>P(S)-], n[>P(0)], n[>P(Cl)<] represent the number of
>P(S)-, >P(0)-, and >P(C1)< groups, respectively, in the
molecule; k[>P(S)-], k[>P(O)-], k[>P(Cl)<] represent the group
rate constants for OH radical interaction with the >P(S)-,
>P(0)-, and >P(C1)< groups, respectively, and the values of
these group rate constants are listed in Table 1 at 298 K.

Pathway 7;  OH radical addition to aromatic rings

     The overall rate constant fcadd,ar for reaction pathway 7
is given by the equations

              *(7) = *add,ar                               (171)
                                                           (172)
Io9l0k'add,ar = ^ I  -31 ~ I-35 Min< .
                               ^add,ar
                             -202-

-------
where V represents the summation over all aromatic rings  in


the molecule; ( TVt ) represents the summation of the


electrophilic substituent constants of Brown and Okamoto  (1958)


with respect to a given ring position (i.e., ortho, meta,


para) ; and Min( })   (175)




                       *add,PAH =  10~12k'add,PAH
where ]F, represents the summation of all PAHs,  (IP)i  represents
       i

the ionization potential of the parent PAH  in electron  volts


(eV) obtained from Weast  (1976-1977);  ( Va} )  is derived  for

                                         J
the monocyclic substituted portion of the molecule  to allow for


the effects of substituent groups on the reactivity and


represents the summation of the electrophilic substituent


constants of Brown and Okamoto  (1958) with  respect  to a given


ring position  (i.e.,  ortho, meta, para); and Min  (
                              -203-

-------
represents the summation of the electrophilic substituent
constants with respect to the ring hydrogen position that gives
the most negative summation value (i.e., Min ).  Electrophilic
substituent constants (ffjj and 
-------
VI11.  References
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Atkinson, R.   (1988).
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                             -205-

-------
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Atkinson, R.; Aschmann, S.M.  (1985).
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Atkinson, R.; Aschmann, S.M.  (1987).
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Atkinson, R.; Aschmann, S.M.  (1988).
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                             -206-

-------
Atkinson, R.; Aschmann, S.M.   (1988a).
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                              -207-

-------
Atkinson, R.; Perry, R.A.; Pitts, Jr., J.N.   (1978).
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                             -208-

-------
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Ohta, T.  (1984).
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                             -218-

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Ravishankara, A.R.; Wagner, S.j Fischer, S.; Smith, G.; Schift,
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                             -220-

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Zetzsch, C.  (1980).
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                             -221-

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 REPORT  DOCUMENTATION
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               . J. eeio>nrj Acention NO.
 . Title and subtitle  Determination of Rates  of Reaction  in the Gas-Phase s. Report Date
 in the Troposphere.   Theory and Practice.  3.  Rate of Indirect
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    This report describes the development of structure/ reactivity (S/R) relation-
 ships of Atkinson for the estimation of the 2&d--order rate constant (k0H)  for tha
 reaction of OH radicals  with organic chemicals  in the troposphere.   These  S/R
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 variety of  classes and compares them with the experimental values (% Error).   Of
 the 405 chemicals, 20 had a % error  > +100 and  were omitted in  the analyses.   For
 the 385 remaining chemicals, the average % error  ranged from +21 to -19.   One
 hundred fifty-four chemicals were not used by Atkinson to derive the parameters in
 the S/R relationships and, therefore,  were good candidates to test the validity of
 the S/R relationships.   The average  percent error of the 154 chemicals ranged from
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 the estimation of the half-life of a chemical in  the troposphere from k^o  and the
 average OH  concentration.  This report represents the technical support document
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   o. Identlftera/Ooen-Cfldod Terma

 OH radical reaction rates in the troposphere  (koH), structure/reactivity
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