Electro-organic reactions. Part 12. The anodic oxidation of alicyclic unsaturated carboxylic acids

Abstract

For 1,2,4-trimethylcyclohexene-4-carboxylic acid voltammetric experiments and controlled potential electrolysis are used to show that the carbon–carbon double bond is more readily oxidised than the carboxylate function. Electro-oxidation in aqueous acetonitrile gives high yields of lactones. These products have been characterised and their formation rationalised. Chlorolactonisation may be achieved by anodic oxidation of chloride in the presence of the acid.

1,2-Dimethylcyclopentene-4-carboxylic acid does not lactonise under any of the above conditions. The stereo-chemical reasons for the difference in behaviour of the two acids is discussed.