Selective mixed coupling of carboxylic acids via unsymmetrical diacyl peroxides by electrolysis,thermolysis and photolysis

Unsymmetrical diacyl peroxides are prepared in 85–92 % yields. Their square pulse electrolysis affords unsymmetrical dimers in poor yield and selectivity. Whilst thermolysis or photolysis in solution produces high portions of disproportionation products, the photolysis of the neat peroxides at ?78° C yields selectively 50–75 % of the mixed dimers.