Polyfluoroalkyl compounds of silicon. Part XII. Reactions of trichlorosilane with 2-chloro- and 2-bromo-1,1-difluoroethylene

Abstract

Photochemical reaction of an excess of trichlorosilane with 2-chloro-1,1-difluoroethylene gives trichloro-(2,2-difluoroethyl)silane as the major product, and smaller amounts of trichloro-(1,1-difluoroethyl)silane and trichloro-(2-chloro-2,2-difluoroethyl)silane, whereas reaction with an excess of olefin present gives mainly trichloro-(2-chloro-2,2-difluoroethyl)silane together with trichloro-(2-chloro-1,1-difluoroethyl)silane. Formation of these products is explained in terms of initial trichlorosilyl radical addition to 2-chloro-1,1-difluoroethylene at the CF₂ group and a competing reduction of the olefin to 1,1-difluoroethylene followed by trichlorosilyl radical addition at the CH₂ group. Photochemical reaction of trichlorosilane with 2-bromo-1,1-difluoroethylene gives the reduced olefin 1,1-difluoroethylene and 2,2-difluoroethyl- and 2-bromo-2,2-difluoroethyl-trichlorosilanes.