The Electroreductive Dehalogenation Reaction of 5-Bromo-2-chlorobenzoic Acid on Dendritic Ag/Cu

Dendritic Ag/Cu electrode was synthesized by galvanic replacement of AgNO3 and Cu, and was investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Cyclic voltammetry and in situ FTIR were combined to study the electroreductive dehalogenation reaction of 5-bromo-2-chlorobenzoic acid (BCBA) on Ag/Cu electrode in NaOH aqueous solution. Ag/Cu electrode exhibited high electrocatalytic activity for the dehalogenation reaction of BCBA. Based on the in situ FTIR data, the electroreductive dehalogenation process of BCBA was represented as a sequence of halide expulsions and hydrogen additions. Because the bond dissociation energy value of C-Br bond was less than that of C-Cl bond, Br-was easier to release from benzene ring. With the C-Br breakage, BCBA received electrons and hydrogen to form intermediate 2-chlorobenzoate. Then C-Cl broke in the same way, and the end product benzoate was obtained.