Radical-cations as intermediates in the oxidation of alkenes by metal ions

Abstract

The formation of hydroxy acetates in the reaction of some alkenes with lead(IV), cobalt(III), and manganese(III) in acetic acid is demonstrated to involve the intermediacy of alkene radical-cations. A study employing a range of aryl-substituted alkenes has shown that there is an inverse relationship between the yield of hydroxy acetate and the ionisation potential of the organic substrate. The electron deficiency in the radica-cations derived from these alkenes appears to be localised on the double bond: no evidence could be obtained for reaction at the aromatic ring. The introduction of a chlorine atom into this ring had the effect of repressing electron-transfer in cobalt(III) and manganese(III) oxidations but not in those involving lead(IV).