Effect of Copper(II) Chloride on the Reaction of 2-Thenoyloxy Radical with lodobenzene

Abstract

The decomposition of 2-thenoyl peroxide in iodobenzene was carried out at 80C. In the presence of copper(II)chloride, iodopheny12-thenoates were produced. The isomer distribution and the partial rate factors suggested that the 2-thenoyloxylation reaction would proceed through the addition of a 2-thenoyloxy radical to an aromatic nucleus to give a cyclohexadienyl radical, fo11owed by rapid oxidation by copper(II)chloride. On the other hand, in the absence of copper(II)chloride the substitution of iodine by 2-thenoyloxy group took place to give phenyl 2-thenoate, which was not detected in the presence of copper(II)chloride. This substitution reaction is best explained on the assumption that the 2-thenoylexy group in the cyclohexadienyl radicals rearranges through an intramolecular migration of the carbonyl group to the carbon bearing an unpaired electron, and that phenyl 2-thenoate arises from a rearranged cyclohexadienyl radical with elimination of the iodine atom.