Hydrogen-transfer and charge-transfer in photochemical and radiation induced reactions. Progress report, November 1, 1975--October 31, 1976

Technical Report · Fri Oct 01 00:00:00 EDT 1976

DOI:https://doi.org/10.2172/7248980· OSTI ID:7248980

Cohen, S. G.

The relative importance of light absorption, quenching of triplet, and hydrogen transfer repair has been examined in retardation by mercaptans of photoreduction of aromatic ketones by alcohols. In the reduction of benzophenone by 2-propanol, retardation is efficient and, after correction for the first two effects, is due entirely to hydrogen-transfer repair, as indicated by deuterium labeling. In reduction of acetophenone by ..cap alpha..-methylbenzyl alcohol, repair by hydrogen transfer is also operative. In reduction of benzophenone by benzhydrol, retardation is less efficient and is due to quenching, as the ketyl radical does not abstract hydrogen from mercaptan rapidly in competition with coupling. Deuterium isotope effects are discussed in terms of competitive reactions. Photoreduction of benzophenone by 2-butylamine and by triethylamine is retarded by aromatic mercaptans and disulfides. Of the retardation not due to light absorption and triplet quenching by the sulfur compounds, half is due to hydrogen-transfer repair, as indicated by racemization and deuterium labeling. The remainder is attributed to quenching by the sulfur compound of the charge-transfer-complex intermediate. Photoreduction by primary and secondary amines, but not by tertiary amines, is accelerated by aliphatic mercaptans. The acceleration is attributed to catalysis of hydrogen transfer by the mercaptan in the charge-transfer complex. The effect is large in hydrocarbon solvent, less in polar organic solvents and absent in water.

• Research Organization: Brandeis Univ., Waltham, Mass. (USA)
• OSTI ID: 7248980
• Report Number(s): COO-3118-11
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400302 -- Organic Chemistry-- Isotope Effects-- (-1987)
400500 -- Photochemistry
400600* -- Radiation Chemistry
AMINES
BENZOPHENONE
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DEUTERIUM
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
KETONES
KINETICS
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RADIATION CHEMISTRY
RADIATION EFFECTS
REACTION KINETICS
STABLE ISOTOPES
THIOLS