Isomerization of 1,2-dichloroethylene induced by Chlorodifluoromethyl Radicals: Formation of Metastable Radicals

Abstract

IT has been reported that radicals produced by the decomposition of benzoyl peroxide in the liquid phase cause the rapid isomerization of cis and trans 1,2-dichloroethylene in the liquid phase in the temperature-range 80°–135° C (refs. 1 and 2). It is supposed that the isomerization is brought about by chlorine atoms which react with the olefines to form 1,2,2-trichloroethyl radicals which rapidly decompose to give the original 1,2-dichloroethylene or its isomer. This reaction has recently been shown to intervene in the chlorination of 1,2-dichloroethylene, even at lower temperatures3. The chlorine atoms in the first mentioned isomerization process are supposed to be formed by displacement from the olefine by a free radical derived from benzoyl peroxide. No direct evidence has previously been obtained for such a process.