Photochlorination studies. Part 10.—Excited chloroalkyl radicals in photochlorination of chloroethylenes

Abstract

The effect of added chemically inactive gases, helium, argon, carbon dioxide and sulphur hexafluoride, on (i) the rate of photochlorination of vinylidene chloride and cis-1,2-dichloroethylene, (ii) the rate of geometrical isomerization of cis-1,2-dichloroethylene, has been studied. The effects have been interpreted in terms of the deactivation of vibrationally excited chloroalkyl radicals for which a mean lifetime of the order of 10^–7 sec is estimated. Relative efficiencies of deactivation by inert gases and by chlorine and olefin molecules have been estimated. Some data relating to the geometrical isomerization of cis- and trans-1,2-dichloroethylene given in part 5 have been corrected and amplified.