United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-98/124 September 1998
EPA Project Summary
Substitution Reactions for the
Detoxification of Hazardous
Chemicals
Fred K. Kawahara
Recent literature on substituting
chemical reagents that will convert toxic
halogenes to their nontoxic hydrocar-
bons was surveyed. Within this cat-
egory of chemical substitution, three
types of reactions are discussed: su-
peroxide ion radical reactions, polyeth-
ylene glycol (PEG) transformations of
PCBs, and catalytic hydrogen transfer
reactions.
This Project Summary was developed
by EPA's National Risk Management
Research Laboratory, Cincinnati, OH,
to announce key findings of the re-
search project that is fully documented
in a separate report of the same title
(see Project Report ordering informa-
tion at back).
Background
Chemical substitution is one of several
techniques available to treat hazardous
chemicals that can threaten the environ-
ment. In the report, briefly summarized
here, chemical treatment is substituting
hydrogens for halogens so as to convert
the halogenated organics to hydrocarbons
or to mineralize the organic to carbon
dioxide, water, or other components).
Three types of reactions applicable to
the conversion of hazardous chlorohy-
drocarbons to their respective nontoxic
hydrocarbons are discussed:
• superoxide ion radical reactions,
• dehalogenation of polyhaloaromatics
and polyhaloalkanes with PEGs; and
• catalytic hydrogen transfer reactions.
Some fundamental aspects of these re-
actions are reported.
With O2 representing molecular oxygen,
a one-electron reduction in its valence
yields the ion radical O2 —. Studies are
cited that demonstrate reactions caused
by this superoxide ion radical, e.g., PCS
oxygenation.
Use of PEG, together with a base such
as potassium hydroxide, has been found
to be a promising technique. On reporting
on processes involving PEG'S use, how
PEG functions as the reactive agent to
dechlorinate PCB is developed.
With the catalytic transfer hydrogena-
tion reactions, organic acceptor molecules
are catalytically reduced with hydrogen
donated by another organic molecule. The
literature review of catalytic transfer hy-
drogenation is restricted to certain reac-
tion conditions and solvent effects and to
some details in molecular donor and ac-
ceptor structures. Studies on the effects
of temperature, solvents, solvents in het-
erogeneous systems, homogeneous ca-
talysis, and heterogeneous catalysis on
transfer reductions are included.
The full report is a valuable survey of
recent literature (incorporating almost 100
citations) on this subject; it is not intended
as a manual on technical application.
Printed on Recycled Paper
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The EPA author, Fred K. Kawahara, is with the National Risk Management
Research Laboratory, Cincinnati, OH 45268.
The complete report, entitled "Substitution Reactions for the Detoxification of
Hazardous Chemicals," (Order No. PB98-177876; Cost: $25.50, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-605-6000
The EPA author can be contacted at:
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
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EPA/600/SR-98/124
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