ONE-ELECTRON REDUCTION OF METHYL(TRIFLUOROMETHYL)DIOXIRANE BY IODIDE-ION - EVIDENCE FOR AN ELECTRON-TRANSFER CHAIN-REACTION MEDIATED BY THE SUPEROXIDE ION

One-electron-transfer processes, triggered by I- in catalytic amounts, convert methyl(trifluoromethyl)dioxirane (1) into 1,1,1-trifluoropropanone (trifluoroacetone) and dioxygen. It is proposed that the initially formed bis(oxy)methylene radical anion 1' performs nucleophilic attack at the dioxirane 1, yielding a dimeric radical anion 2'; the latter then fragments into trifluoroacetone and superoxide ion (O2.-). The intermediacy of superoxide ion (the propagator of the electron-transfer chain reaction) is demonstrated by its trapping with either benzoyl chloride or chlorotrimethylsilane. Also, potassium superoxide in catalytic amounts induces the fast and complete conversion of 1 into trifluoroacetone with evolution of dioxygen. The redox reaction between dioxirane 1 and iodide ion in acidic medium yields substantial amounts of hydrogen peroxide, which was detected by the catalase probe.