Electrogenerated luminescence in the Kolbe reactions of pyruvic and phenylglyoxylic acids

Abstract

The Kolbe reaction of pyruvic and phenylglyoxylic acids in acetonitrile takes place with high yields of biacetyl and benzil, respectively. Electroluminescence is produced during the electrolysis. This luminescence can be attributed to phosphorescence following the generation of excited triplets of the α-diketones in the acyl radical recombination. The efficiencies of the triplet production, relative to ground state formation, were evaluated to be of the order of 8 × 10−3 and 10−1 for the recombination leading to benzil and biacetyl, respectively.