Scalable Electrochemical Dehalogenative Carboxylation without a Sacrificial Metal Anode

A scalable electrochemical procedure for the synthesis of carboxylic acids from organic halides has been developed using a spinning cylinder electrode electrochemical reactor. The electrochemical process is based on the reductive dehalogenation of the starting material followed by trapping of the resulting carbanion with CO2. The protocol is compatible both with organic chlorides and bromides and uses inexpensive graphite and stainless steel as electrode materials. As sacrificial metal anodes are avoided, the method can be readily scaled up in flow mode. The procedure is compatible with a wide range of substrates (24 examples), including aryl and alkyl halides as well as heterocyclic compounds. Multigram scale preparations in flow mode have been demonstrated by processing 600 mL of reaction mixture in an electrolyte recirculation setup.