Recent advances in oxidative valorization of lignin

Lignin, an aromatic macromolecule synthesized by all higher plants, is one of the most intriguing natural materials for utilization across a wide range of applications. Depolymerization and fragmentation of lignin into small chemicals constituents which can either replace current market products or be used building blocks for new material synthesis is a focus of current lignin valorization strategies. Among the variety of lignin degradation chemistries, catalytic oxidation of lignin presents an energy efficient means of lignin depolymerization and generating selective reaction products. This review provides a summary of the recent advancements in oxidative lignin valorization couched in a discussion on how these chemistries may contribute to the degradation of the lignin macromolecule through three major approaches: 1) inter-unit linkages cleavage; 2) propanyl side chain oxidative modification; and 3) oxidation of the aromatic ring and ring cleavage reactions.