vvEPA
United States
Environmental Protection
Agency
Environmental Research
Laboratory
Athens GA 30613-7799
Research and Development
EPA/600/M-89/009 Aug. 1990
ENVIRONMENTAL
RESEARCH BRIEF
Pathway Analysis of Chemical Hydrolysis for 14 RCRA Chemicals
Heinz P. Kollig, J. Jackson Ellington, Eric J. Weber, and N. Lee Wolfe
The probable pathways of transformation by chemical
hydrolysis in an aqueous environment were postulated for
14 chemicals. Acid, base, and neutral half-lives at pH 7
are given for the chemicals and their products. A
structural formula is provided for each chemical.
Introduction
Assessment of potential risk posed to humans by man-
made chemicals in the environment requires the
prediction of environmental concentrations of those
chemicals under various scenarios. Whether mathematical
models or other assessment techniques are employed,
knowledge of equilibrium and kinetic constants (fate
constants) is required to predict the transport and
transformation of these chemicals.
Under section 301 of the Resource Conservation and
Recovery Act (RCRA), EPA's Office of solid Waste (OSW)
has identified wastes that may pose a substantial hazard
to human health and the environment. RCRA requires that
EPA develop and promulgate criteria for identifying and
listing hazardous wastes, taking into account, among other
factors, persistence and degradability in the environment.
In 1986, OSW proposed additions to the list of chemicals
regulated under the Toxicity Characteristic section of
RCRA. A land disposal decision model developed at the
Environmental Research Laboratory in Athens, Georgia
(ERL-Athens) was applied to determine maximum
permissible leachate concentrations resulting from the
Toxicity Characteristic Leachate procedure for the
additional chemicals. ERL-Athens had provided hydrolysis
rates and sorption data for these chemicals. Response to
the Federal Register proposals for regulated concen-
trations prompted OSW to (1) change some transport
functions in the model and (2) remove from the list 15
chemicals that hydrolyze in order to evaluate these
chemicals in more depth.
OSW requested that ERL-Athens postulate the probable
pathways of transformation in an aqueous environment by
chemical hydrolysis for the 15 chemicals. The' chemicals
were acrylonitrile, carbon tetrachloride, chlordane, 6/s(2-
chloroethyl)ether, chloroform, 1,2-dichloroethane, hepta-
chlor, lindane, methoxychlor, methylene chloride, 1,1,1-
trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-tetrachloro-
ethane, 1,1,2,2-tetrachloroethane, and toxaphene. Toxa-
phene was not addressed in the pathway analysis,
-------
however, because it is a mixture of more than 600
polychlorinated terpenes.
Pathway Analysis
A team of scientists met to discuss the hydrolysis rates
and probable pathways of transformation. The methods
used to arrive at the reaction products were based
primarily on the team's experience with similar
compounds, their knowledge of the hydrolysis theory, and
their understanding of structure activity relationships. The
final stable products were identified as containing either no
hydrolyzable functional group (NHFG) or non-labile
functional group (NLFG). Although the molecule with a
non-labile functional group contains one or more
heteroatoms, they are so unreactive towards hydrolysis
that they will not hydrolyze. (Over the pH range of 5 to 9
and at 15SC, half-lives will be greater than 50 years if they
react at alt.)
Literature searches were conducted afterwards to find
needed fate data for the intermediate products of
hydrolysis. If the literature failed to provide the required
data, they were determined in the laboratory if possible. All
half-lives were calculated at pH 7. The values were arrived
at by adding the acid and/or base portion of the rate
constant at pH 7 to the neutral rate constant and
calculating the half-life according to: t1'2 = (In 2)/rate
constant.
Acrylonitrile (Rgure 1) hydrolyzes through the intermediate
product acrylamide to acrylic acid, a compound that has
no hydrolyzable functional group. Ammonia is formed
along with acrylic acid.
107-13-1
acrytonitrite; Ref. 1
kA - 3.7E2 M-'Y-i
ka - 5.3E3
t"2 - 1.2E3 Y
79-06-1
acrylamkte; Ref. 1
kA - 31.5 M-1Y-1
kM - 1.8E-2Y-1
t"2 - 38 Y
79-10-7
acrylic acid
NHFG
CH2=CHCN
CH2=CHCONHa
CH2=CHCOOH
Figure 1. Acrylonitrile, hydrolysis pathway.
Carbon tetrachloride (Figure 2) hydrolyzes to inorganic
products, carbon dioxide and hydrogen chloride, with no
detectable intermediates.
Chlordane (Figure 3) hydrolyzes to the final stable product,
2,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-4,7-
methano-1H-indene. Hydrogen chloride is formed in the
process. No other products have been observed. (Only the
c/s-isomer, CAS #5103-74-2, undergoes hydrolysis due to
the 1 -exo, 2-exo orientation of the chlorine.)
56-23-5
carbon tetrachloride; Ref. 3
kN = 1.7E-2Y-1
t1'2 = 41 Y
ecu
124-38-9
carbon dioxide
C02
NHFG
7647-01-0
hydrogen chloride
4HCI
NHFG
Figure 2. Carbon tetrachloride, hydrolysis pathway.
57-74-9
chlordane; Ref. 4
kB = 38 M-'Y-1
ti« = 1.8E5Y
5103-65-1
2,4,5,6,7,8,8-heptachloro-3a,4,7,7a-
tetrahydro-4,7-methano-iH-indene
NLFG
Figure 3. Chlordane, hydrolysis pathway.
bis(2-Chloroethyl)ether (Figure 4) hydrolyzes through the
intermediate product, 2-(2-chloroethoxy)ethanol, to the final
stable products, 6/s(2-hydroxyethyl)ether and para-
dioxane. The 2-(2-chloroethoxy)ethanol will build to a
significant steady state concentration. Hydrogen chloride is
formed in the process.
Chloroform (Figure 5) hydrolyzes to inorganic products,
carbon dioxide and hydrogen chloride.
-------
111-44-4
CICH2CH2OCH2CH2CI
b/s(2-chloroethyl)ether; Ref 2
kN = 0.23 Y-1
ti/2 = 3.0 Y
628-89-7
CICH2CH2OCH2CH2OH
2-(2-chloroethoxy)ethanol; Ref. 2
kN = 0.28 Y-1
ti/2 = 2.5 Y
0
123-91-1
p-dioxane; Ref. 11
NHFG
111-46-6
HOCH2CH2OCH2CH2OH
fa/s(2-hydroxyethyl)ether; Ref. 11
NHFG
75-01-4
vinylchloride; Ref. 6
CH2 = CHCI
kB<3.5M-iY-i
kN<7.0E-2Y-i
t1/2>10 Y
74-86-2
acetylene
CH^CH
NHFG
107-06-2 CICH2CH2CI
1,2-dichloroethane; Ref. 3
kB =5.5E-6 M-1Y-1
kN = 9.6E-3 Y-1
tl/2 =
107-07-3
2-chloroethanol; Ref. 2
CICH2-CH2OH
kN = 3.9E-2 Y-i
75-07-0
acetaldehyde
CH3-CHO
NHFG
107-21-1
ethylene glycol
HOCH2-CH2OH
NHFG
Figure 6. 1,2-Dichloroethane, hydrolysis pathway.
Figure 4. ft/s(2-Chloroethyl)ether, hydrolysis pathway.
67-66-3
chloroform; Ref. 5
kB = 2.1E3 M-1Y-1
kN = 2.3E-5 Y-1
ti/2 = 3.QE3 Y
CHCI3
124-38-9
carbon dioxide
C02
NHFG
7647-01-0
hydrogen chloride
3HCI
NHFG
76-44-8
heptachlor; Ref. 9
kN = 56Y-1
t1'2 = 1.2E-2Y
24009-05-0
1 -hydroxychlordene
NLFG
Cl
Figure 7. Heptachlor, hydrolysis pathway.
Figure 5. Chloroform, hydrolysis pathway.
1,2-Dichloroethane (Figure 6) hydrolyzes to the fairly
stable product vinyl chloride and to the final stable product
ethylene glycol through the intermediate product 2-
chloroethanol. Vinyl chloride may further hydrolyze to
acetylene at alkaline pHs or to acetaldehyde at near
neutral pH. Ethylene glycol is the main product at near
neutral pH, and the reaction shifts to give vinyl chloride as
the pH increases. Hydrogen chloride is formed in the
process.
Heptachlor (Figure 7) hydrolyzes to 1-hydroxychlordene,
which has an estimated half-life of longer than 8 million
years at pH 7. Hydrogen chloride is formed in the process.
Lindane (Figure 8) hydrolyzes through the intermediate
product, 1,3,4,5,6-pentachlorocyclohexene, to the final
stable products, 1,2,3-trichlorobenzene and 1,2,4-trichloro-
benzene. Hydrogen chloride is formed in the process.
Methoxychlor (Figure 9) hydrolyzes to the final stable
product, 2,2-bis(p-methoxyphenyl)-1,1 -dichloroethylene
under alkaline conditions, and to the final stable product
anisil through the intermediate product anisoin under
acidic or near neutral conditions. Hydrogen chloride is
formed in the process. Anisoin oxidizes to anisil. A rate of
oxidation was not available.
Methylene chloride (Figure 10) hydrolyzes with no
detectable intermediates to the final stable products,
formaldehyde and hydrogen chloride.
-------
58-89-9
lindano; Ref. 4 ci
ka « 1.74E6M-1Y-1
kN-1.05Y-i cl
It/2 = 0.5 Y
ci
O
ci
I
ci
319-94-8
1,3,4,5,6-pentachlorocyclohexene; Ref. 2
kB - 6.5E5 M-»Y-1
kN - 0.26 Y-i
lira . 2.1 Y
CJ
ci
i
ci
CJ
I
CI
87-61-6
1,2,3-trtohtorobenzene
120-82-1
1,2,4-trichlorobenzene
ci
i
Llndane, hydrolysis pathway.
1,1,1-Trichloroethane (Figure 11) hydrolyzes to the two
final stable products, acetic acid and 1,1-dichloroethene.
Hydrogen chloride is formed in the process. The ratio of
acetic acid to 1,1-dichloroethene is dependent on pH and
temperature. Production of 1,1-dichloroethene increases
directly with pH and temperature.
1,1,2-Trichloroethane (Figure 12) hydrolyzes to the final
stable product hydroxyacetaldehyde through the
intermediate product chloroacetaldehyde and to the final
stable product 1,1-dichloroethene. Hydrogen chloride is
formed the process.
1,1,1,2-Tetrachloroethane (Figure 13) hydrolyzes to the
final product, 1,1,2-trichloroethylene. Hydrogen chloride is
formed in the process.
1,1,2,2-Tetrachloroethane (Figure 14) hydrolyzes to the
final product, 1,1,2-trichloroethylene. Hydrogen chloride is
formed in the process.
72-43-5
meUioxychtor; Ref. 7
ks - 1.2E4 M-1Y-1
(CN » 0.69 Y-'
ti/2 . 1.0 Y
CH3O -'
-CH -
CGI,
-OCH3
2132-70-9
2,2-bis(p-melhoxyphenyl)-
1,1-dicriloroethylene; Ref. 7
119-52-8
anisoin; Ref. 7
CH3-0-
CH3-0-
- O - CH3
- O - CH3
1226-42-2
anisil; Ref. 7
NLFG
CH3-0-
- O - CH3
NHFG
Figure 9. Methoxychlor, hydrolysis pathway.
-------
75-09-2
methylene chloride; Ref. 8
kN = 1.01E-3Y-1
ti/2 = 686 Y
50-00-0
formaldehyde
CH2 = O
NHFG
CH2CI2
7647-01 -0
hydrogen chloride
2HCI
NHFG
630-20-6
1,1,1,2-tetrachloroethane; Ref. 3
kB = 1.1E4M-1Y-1
kN = 1.4E-2Y-1
ti/2 = 47 Y
79-01-6
1,1,2-trichloroethylene; Ref. 3
NLFG
CCI3CH2CI
CCI2 = CHCI
Figure 10. Methylene chloride, hydrolysis pathway.
71-55-6
1,1,1-trichloroethane; Ref. 3
kN = 0.65 Y-1
t1/2 = 1.1 Y
64-19-7
acetic acid
CH3-COOH
NHFG
CCI3CH3
75-35-4
1,1-dichloroethene
CCI2 = CH2
NLFG
Figure 11. 1,1,1-Trichloroethane, hydrolysis pathway.
Figure 13. 1,1,1,2-Tetrachloroethane, hydrolysis path-
way.
79-34-5
1,1,2,2-tetrachloroethane; Ref. 3
kB = 1.7E7 M-IY-I
kN = 5.1E-3Y-1
ti/2 = o.41 Y
79-01-6
1,1,2-trichloroethylene; Ref. 3
NLFG
CI2CHCHCI2
CCI2 = CHCI
Figure 14. 1,1,2,2-Tetrachloroethane, hydrolysis path-
way.
CI2CHCH2CI
79-00-5
1,1,2-trichloroethane; Ref. 3
kB = 5.0E4 M-1Y-1
kN = 2.7E-5 Y-1
ti« = 1.4E2 Y
107-20-0
chloroacetaldehyde; Ref. 10
CICH2CHO
kB = 2.6E4 M-IY-I
kN = 7E-3 Y-i
ti/2 = 72 Y
141-46-8
hydroxyacetaldehyde
OHCH2CHO
NHFG
Figure 12. 1,1,2-Trichloroethane, hydrolysis pathway.
75-35-4
1,1 -dichloroethene
CCI2 = CH2
NLFG
References
1. Ellington, J. J., F. E. Stancil, and W. D. Payne.
1986. Measurement of hydrolysis rate constants for
evaluation of hazardous waste land disposal.
Volume I. U.S. Environmental Protection Agency,
Athens, GA. EPA/600/3-86/043.
2. Ellington, J. J., F. E. Stancil, W. D. Payne, and C.
D. Trusty. 1988. Measurement of hydrolysis rate
constants for evaluation of hazardous waste land
disposal. Volume III. Data on 70 chemicals. U.S.
Environmental Protection Agency, Athens, GA.
EPA/600/3-88/028.
3. Jeffers, P. M., L. Ward, L. Woytowitch. and N. L.
Wolfe. 1989. Homogeneous hydrolysis rate
constants for selected chlorinated methanes,
ethanes, ethenes and propanes. Environ. Sci.
Technol. 23(8):965-969.
4. Ellington, J. J., F. E. Stancil, W. D. Payne, and C.
D. Trusty. 1987. Measurement of hydrolysis rate
constants for evaluation of hazardous waste land
disposal. Volume II. Data on 54 chemicals. U.S.
Environmental Protection Agency, Athens, GA.
EPA/600/3-87/019.
-------
5. Fells, I. and E. A. Moelwyn-Hughes. 1959. The kinetics
of the hydrolysis of the chlorinated methanes. J.
Chem. Soc., Part 1. No. 72:398-409.
6. Hill, J., H. P. Kollig, D. F. Paris, N. L Wolfe, R. G.
Zepp. 1976. Dynamic behavior of vinyl chloride in
aquatic ecosystems. U.S. Environmental Protection
Agency, Athens, GA. EPA/600/3-76/001.
7. Wolfe, N. L, R. G. Zepp, D. F. Paris, G. L. Baughman,
R. C. Hollis. 1977. Methoxychlor and DDT degradation
in water; Rates and products. Environ. Sci. Technol.,
11:1077-1081.
8. Fells, I. and E. A. Moelwyn-Hughes. 1958. The kinetics
of the hydrolysis of methylene dichloride. J. Chem.
Soc., Part 2, No. 268:1326-1333.
9. Chapman, R. A. and C. M. Cole. 1982. Observations
on the influence of water and soil pH on the
persistence of insecticides. J. Environ. Sci. Health
B17(5):487-504.
10. Osterman-Golkar, S. 1984. Reaction kinetics in water
of chloroethylene oxide, chloroacetaldehyde, and
chloroacetone. Hereditas, 101:65-68.
11. Payne, W. D. and T. W. Collette. 1989. Identification of
bis(2-chloroethyl)ether hydrolysis products by direct
aqueous injection GC/FT-IR. HRC 12:693-696.
-------
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/600/M-89/009
------- |