Electrochemical reduction of N-(2,2,2-trichloroethyl)acetamides

Abstract

The electrochemical reduction, at a mercury cathode, of dimethylformamide solutions, containing Et₄NClO₄ as supporting electrolyte, of N-(2,2,2-trichoroethyl)acetamides (1a–f), with or without added water as proton source, has been investigated. In all cases, the nature and yield of the products from macroscale electrolyses as well as voltammetric data point to the formation of an intermediate carbanion, which undergoes β-elimination, or α-elimination, or acid–base reaction depending on the nature of the substituent on the carbon α to nitrogen and the medium. The formation of (2a) from the electrolysis of (1a–b) in the presence of H₂O has been ascribed to nucleophilic substitution of the first-formed dehalogenated product by dimethylamine. The latter arises from decomposition of the solvent promoted by ions released in the follow-up reactions of the carbanion.