Cu@CuCl-visible light co-catalysed chlorination of C(sp3)–H bonds with MCln solution and photocatalytic serial reactor-based synthesis of benzyl chloride

Abstract

A highly selective, green and sustainable chlorination of aliphatic C–H bonds is reported using MCl_n under the co-catalysis of visible light and nano-Cu@CuCl, which was synthesised via a one-step, hydrothermal strategy using copper(II) sulfate and D-glucose as the reducing agent in a KCl solution. A novel cascade method of producing Cl₂ occurs in situ chlorinating C(sp³)–Hs, achieved through nano-Cu@CuCl catalysis using inorganic chloride MCl_n as a chlorine source under visible light and without the need for a strong oxidant. The reaction was applied to the chlorination of different alkylarene α-Hs and cyclic hydrocarbons C–H_S and was developed for use in a photocatalytic serial reactor system which accomplished the chlorination of toluene α-Hs to give 92% conversion, 90% yield and 98% selectivity. Electron spin resonance (ESR) studies of DMPO-Cl. revealed that the reaction mechanism belonged to a free radical process.