Free Radical Addition to Olefins: Part 12.—Addition of Bromodifluoromethyl Radicals to Fluoroethylenes

Abstract

The kinetics of the photochemical addition of dibromodifluororncthanc to vinyl fluoride, 1,1- difluoroethylene and tetrafluoroethylene has been examined in gas phase experiments. The mech anism involves the addition of CF2Br- radicals to the alkene in a chain reaction. In the accessible range of alkene concentrations the chains are terminated not only by dimerization of the CF2Br- radicals but also by cross-terminations involving CF2Br- radicals and adduct radicals. Relative rate constants and Arrhenius parameters for the addition of CF2Br- radicals to specific sites in the alkenes have been measured from competitive experiments with ethylene. An estimate of the absolute Arrhenius parameters for the addition of CF2Br- radicals to ethylene is also given.