Catalytic Cleavage of Lignin C–C Bonds and Subsequent Amination: A Valorization Roadmap

ABSTRACT Lignin is the most abundant source of renewable aromatic compounds in natural biomass, yet its efficient depolymerization into aromatic chemicals is severely hampered by the high bond dissociation energy (BDE) of inter‐monomeric linkages, especially the inert C–C bonds. Additionally, integrating the cleaved products from lignin with downstream amination to produce aromatic amines holds great promise for further expanding product applications and enhancing the sustainability and economic feasibility of biomass refinery. Generally, most existing studies focus either on the design of catalytic systems for bond cleavage in lignin to endow green chemical manufacturing or on the amination of aromatic chemicals (phenols, aromatic alcohols, aromatic aldehydes, and aromatic acids, etc.) to synthesize higher‐value‐added products, including several comprehensive review articles. Nevertheless, there remains a critical gap between the challenges in lignin refining and the demands of product amination that needs to be bridged. In this review, by systematically integrating the complete reaction pathway from C–C bond cleavage in lignin to subsequent amination of its product, we aim to elucidate the key mechanisms and pathway design strategies for both processes. Our goal is to provide theoretical guidance for the design of multifunctional catalytic systems that couple bond cleavage and amination. Finally, future research prospects for the complete conversion of lignin into nitrogen‐containing chemicals are outlined, with the purpose of offering a theoretical basis and technical insights for developing novel catalytic systems that combine atom economy, green chemistry, and industrial scalability.