The role of copper(II) salts in the oxidation of aryl-substituted alkenes by peroxydisulphate anion

Abstract

The effect of copper(II) ions on the oxidation, in acetic acid, of aryl-substituted alkenes by peroxydisulphate anion has been investigated. In the presence of the metal ions an electron-transfer process operates akin to that identified in the oxidation of alkenes by other one-electron oxidants. It is suggested that the electron-transfer agent is copper(III) and that the resultant alkene radical-cation is converted into hydroxy acetates in good yield. S₂O₈^2– alone decomposes more slowly to SO₄˙^– which undergoes radical addition to the alkene leading ultimately to diacetates. The presence of sodium acetate in the system reduces considerably the conversion of alkene as a result, it is suggested, of competitive oxidation of the acetate anion.