Decomposition of diacyl peroxides. Part 9. Mechanism of the carboxy-inversion process in the thermal decomposition of benzoyl cyclohexanecarbonyl peroxide and related diacyl peroxides

Abstract

Mechanisms of the carboxy-inversion process in the thermal decomposition of benzoyl cyclohexanecarbonyl peroxide and related diacyl peroxides have been investigated in detail by elabolate ¹⁸O-tracer experiments which involve measurements of ¹⁸O-scrambling of benzoyl cyclohexyl carbonate resulting from the initial carboxy-inversion process under the reaction conditions. A detailed analysis of the ¹⁸O-tracer experimental results reveals that the carboxy-inversion process of Case I and II peroxides involves three kinds of ion pairs. The extents of the contribution of these ion pairs in the carboxy-inversion process of benzoyl cyclohexanecarbonyl, peroxide and m-chlorobenzoyl cyclohexanecarbonyl peroxide have been determined. Details of the mechanisms of the thermal decomposition of diacyl peroxides have been discussed based on the ¹⁸O-tracer, kinetic, product-distribution and CIDNP experimental results and solvent effects on the decomposition.