Conversion of Lignin Models by Photoredox Catalysis.

One prominent goal of 21st century research is to develop a sustainable carbon-neutral biorefinery. Lignin is an important component of lignocellulosic biomass; however, it is currently underutilized owing to its highly cross-linked, complex, and randomly polymerized composition, which poses a significant challenge to its depolymerization and valorization. Chemical catalytic approaches based on transition metals represent the primary research area to drive degradation reactions. Recently, alternative photocatalytic strategies that employ sustainable solar energy to initiate the transformation of lignin have started to emerge. This Concept article examines new developments of photocatalyzed reactions and provides insight into C-O and C-C bond-cleavage reactions of lignin models in both homogeneous and heterogeneous systems.