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.