Electrolyses of some α-keto-carboxylic acids

Abstract

The Kolbe reaction is largely suppressed when α-oxobutyric and α-oxovaleric acids are electrolysed in methanol with sodium added, by formation of a mixture of three methyl esters: (1) of unsubstituted acid with one carbon atom less than the electrolysed acid, (2) of electrolysed α-keto-acid, (3) of α-hydroxy-acid with the same carbon chain as the electrolysed α-keto-acid. Evidence is provided that α-hydroxy-esters are formed by reduction of α-ketoesters and that the hydrogen comes from the hydroxy-group of methanol. The reduction does not occur when the keto-group is further removed from the ester group or when the methyl group is attached to the carbonyl group of the α-keto-ester.