Electrochemical behaviour of halogenoamides. The role of additional functional groups on the reduction pattern and the nature of the products

Abstract

The electrochemical reduction of halogenoamides (II)–(V) in dimethylformamide solutions containing Et₄NClO₄ as supporting electrolyte, was investigated both at mercury and at vitreous carbon electrodes. Bromoamides (II) and (III) undergo one-electron reduction yielding the debrominated amides CH₃CONHC₆H₁₁(I) and CH₃CONHCHCCl₂(VI) respectively, together with polymeric material. The nature and yield of these products account for a reduction pathway involving both electrochemically generated (e.g.c.; H₂CONHR) and derived (d.c.; HBrCONHR) carbanions. The presence of other functional groups causes a marked alteration of the reaction pathway as shown in the reduction of the amides (IV) and (V), where only products derived from e.g.c. are formed. The formation of amide (VII) together with (VI) from the macroscale electrolysis of bromoacetoxyamide (V) is regarded as an example of electrode-assisted nucleophilic substitution.