RADIATION-INDUCED OXIDATION OF 2-PROPANOL BY DIALKYL PEROXIDE

Solutions of di-t-butyl peroxide in 2-propanol have been subjected to 60Co γ irradiation. Under alkaline conditions di-z-butyl peroxide was reduced to Z-butyl alcohol and the solvent oxidized to acetone according to the stoichiometry (t-BuO)2 + Me2CHOH → 2t-BuOH + Me2CO. Yields were independent of alkali concentration when the latter exceeded about 2 X 10-2 M, but were first order in peroxide concentration. The magnitudes of the yields indicate a chain reaction. It is proposed that the chain is initiated by radiolytic intermediates that undergo hydrogen abstraction reactions with the solvent to produce dimethylhydroxymethyl radicals (I). The latter ionize, and the resulting radical anions (II) undergo a redox reaction with di-t-butyl peroxide, decomposing it to t-butoxide and a free radical (Z-butoxy) that can regenerate I from the solvent. The chain reaction exhibits a dose-rate dependence that is consistent with termination being second order in chain carrier. Retardation and inhibition were observed in the presence of compounds that may be expected to undergo nondissociative electron transfer with II (nitrobenzene, benzophenone, oxygen, sulfur hexafluoride, perfluorocyclobutane) but were not observed in the presence of neutral free radical scavengers (1-hexene, benzene) or compounds that may be expected to dissociate on electron capture (methyl bromide, bromobenzene, carbon tetrachloride, nitrous oxide). © 1968, American Chemical Society. All rights reserved.