Reactions of trifluoromethyl radicals with organic halides. Part 5.—Fluoromethanes and fluoroethanes

Abstract

Hexafluoroacetone has been photolyzed in the presence of CH4, CH3F, CH2F2, CF3CH3, CF2HCF2H and CF3CF2H. Arrhenius parameters are obtained for the abstraction of H by CF3 radicals using the combination of CF3 radicals as a reference reaction. Results were checked by photolysis of hexafluoroacetone in the presence of CD4 plus each of the fluoroethanes and CH4 in turn and using the reaction, CF3+CD4→CF3D+CD3, as a reference. The activation energies obtained are compared with those for related series involving abstraction of H by CF3 and CH3 radicals and by bromine atoms. The secondary products of the system CF3+CH2F2 have been measured. For the combination and cross-combination reactions of CF3 and CHF2 radicals, we obtain ϕ= 2.4 independent of temperature in the range 291–363°C. It is concluded that the second of the reactions [graphic omitted] occurs to a negligible extent.