Selective Depolymerisation of γ-Oxidised Lignin via NHC Catalysed Redox Esterification

Abstract

The development of new catalytic methods for the processing of lignocellulose-derived renewable feedstocks continues to gain momentum, despite the considerable challenges associated with the use of complex biopolymers such as lignin. Here, we report a new two-step depolymerisation method for lignin involving primary alcohol oxidation followed by a NHC-mediated redox esterification-depolymerisation step. The process takes advantage of the inherent structure of the β-aryl ether units present in the specific type of lignin that was used (butanosolv) and delivers 4 novel aromatic monomers which retain the C3 side chain present in the lignin subunits. The utility of the major product is assessed suggesting that rapid access to a wide range of interesting chemical could be achieved from this renewable building block.