Electrolysis for the benign conversion of renewable feedstocks

Abstract

A large variety of C,C-bond forming reactions and functional group interconversions can be achieved by electron transfer. For the conversion of renewable feedstocks, electrolysis has been applied to coupling of radicals generated by anodic decarboxylation of fatty acids and carboxylic acids of carbohydrates. Furthermore, a derivative of L-gulonic acid is converted nearly quantitatively into L-xylonolacton. Trimethyl aconitate from trimethyl citronate is dimerized stereoselectively at the cathode in 72 % yield to a cyclic hexamethyl ester by an inter- and intramolecular Michael addition. Two acetoxy groups are added anodically to methyl conjuenate (obtained from methyl linoleate) to form methyl (E)-9,12-diacetoxy-10-octenoate and methyl (E)-10,13-diacetoxy-11-octenoate in 85 % yield. The primary hydroxy groups in mono- and disaccharides can be oxidized to carboxylic acid groups in good yield and high selectivity by anodic oxidation with 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) as mediator. The results demonstrate that electrolysis is in good accordance with many of the 12 principles of green chemistry.