Carbon-Carbon Bond Cleavage for Lignin and Plastics Deconstruction

The cleavage of C-O bonds has enabled significant progress in both lignin valorization and recycling of polyester plastics. However, for the more recalcitrant fraction(s) of these feedstocks - namely, C-C linkages found in lignin and polymer backbones - the selective cleavage of C-C bonds remains a critical challenge. Selective cleavage of these bonds is essential to enhance both the carbon efficiency and economic viability of biorefining and plastics deconstruction to value-added products. This review provides an overview of the available methodologies for C-C bond cleavage useful for lignin and plastics deconstruction, with particular focus on accessible reaction mechanisms. Methods for C-C bond cleavage from other areas of chemistry are considered alongside approaches specifically applied to lignin and plastics. We provide perspective on promising C-C bond cleavage methods, substrate classes, engineering considerations, and guidelines for reporting C-C bond cleavage yields.