THERMALLY AND PHOTOCHEMICALLY INITIATED RADICAL CHAIN DECOMPOSITION OF KETONE-FREE METHYL(TRIFLUOROMETHYL)DIOXIRANE

Ketone-free solutions of methyl(trifluoromethyl)dioxirane (1) were obtained for the first time in several inert solvents, which enabled the study of the thermal and photochemical decompositions of dioxirane 1 in gas, solution, and matrix phases. Vacuum flash pyrolysis of dioxirane 1 afforded exclusively methyl trifluoroacetate (3a). Both gas- and liquid-phase photolyses and thermal liquid-phase decomposition of dioxirane 1 involve a radical chain process, initiated by attack of CH3 and CF3 radicals on dioxirane 1 to give alpha-alkoxy-substituted alkoxy radicals as intermediates; the latter are responsible for the production of esters 3a-d. Matrix-phase photolysis of dioxirane 1 led to methyl trifluoroacetate (3a) and 1,1,1-trifluoroethane as main products, while gas-phase pyrolysis gave exclusively the ester 3a.