Selective Cleavage of Cβ−O−4 Bond for Lignin Depolymerization via Paired‐Electrolysis in an Undivided Cell

Abstract

AbstractThe cleavage of C−O bonds is one of the most promising strategies for lignin‐to‐chemicals conversion, which has attracted considerable attention in recent years. However, current catalytic system capable of selectively breaking C−O bonds in lignin often requires a precious metal catalyst and/or harsh conditions such as high‐pressure H2 and elevated temperatures. Herein, we report a novel protocol of paired electrolysis to effectively cleave the Cβ−O−4 bond of lignin model compounds and real lignin at room temperature and ambient pressure. For the first time, “cathodic hydrogenolysis of Cβ−O−4 linkage” and “anodic C−H/N−H cross‐coupling reaction” are paired in an undivided cell, thus the cleavage of C−O bonds and the synthesis of valuable triarylamine derivatives could be simultaneously achieved in an energy‐effective manner. This protocol features mild reaction conditions, high atom economy, remarkable yield with excellent chemoselectivity, and feasibility for large‐scale synthesis. Mechanistic studies indicate that indirect H* (chemical absorbed hydrogen) reduction instead of direct electron transfer might be the pathway for the cathodic hydrogenolysis of Cβ−O−4 linkage.