Reactions of trifluoromethyl radicals with organic halides. Part 7.—Chloro- and fluorochloro-ethanes

Abstract

The reactions of CF3 radicals with the compounds C2H5Cl, CH2ClCH2Cl, CH3CHCl2, CH3CCl3, CHCl2CHCl2, CF3CH2Cl, CF3CHCl2, CF3CCl3, CF2ClCFCl2 and CH3CF2Cl were studied. Arrhenius parameters were measured for abstraction of H by CF3, where the molecule contained abstractable H, and for abstraction of Cl by CF3 from most of the multi-chlorinated molecules. Reactions of some of the chloroethanes were complicated by αβ-elimination of HCl, photosensitized by the hexafluoroacetone which was used as a source of CF3 radicals. However, it is believed that reliable rate constants for abstraction were measured. The variations in activation energies for H and halogen abstraction are discussed in terms of polar effects and enthalpy changes. There are substantial variations in A factors for both H and halogen abstraction by CF3 and there is a correlation between variations in A and E both for hydrogen abstraction and halogen abstraction.