Mercaptans and Disulfides as Inhibitors of Non-chain Photochemical and Radiation-induced Reactions
The photochemical conversion of benzophenone and 2propanol to benzpinacol and acetone is retarded and inhibited by certain mercaptans and disulfides present in low concentration. The retarded reactions start at time zero and proceed at essentially constant rate with zero-order kinetics. Inhibition does not lead to consumption of the inhibitor, initially present mercaptan or disulfide being converted to an equilibrium mixture of the two. Inhibited reactions carried out in optically active 2-octanol in place of 2- propanol lead to racemization; irradiation of active 2octanol with benzophenone or disulfide separately does not lead to racemization. Inhibition results from repeated reaction of the sulfur compounds in their two valence states with the normal free radical intermediates, the sulfur compounds being converted to their alternate, still reactive, valence states, the radicals being converted to the starting matertals. The Co⁹⁰ gamma ray-induced conversion of benzophenone to benzpinacoi in 2-propanol is also inhibited by mercaptan and disulfide, presumably by a similar mechanism. These reactions provide a chemical mechanism by which one molecule may dissipate the energy introduced by, and the chemical consequences of, the absorption of many quanta of radiation. (auth)
- Research Organization:
- Brandeis Univ., Waltham, Mass.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-006146
- OSTI ID:
- 4736989
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 20 Vol. 84; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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