Cathodic behaviour of weak acids in acetonitrile: New decarboxylation route of diarylacetic acids cyclically conjugated

The reduction of weak acids in organic media was investigated. For diarylacetic acids cyclically conjugated, the reduction was found to consume less than one electron per molecule and gives side-products with almost no hydrogen evolution. In particular, the unexpected cathodic decarboxylation of fluorene-9-carboxylic and 4-(4H-cyclopenta[2,1-b;3,4-b′])dithiophene carboxylic acids was related. A mechanism is proposed to explain this original decarboxylation route.