Waste plastic upcycling via homogeneous catalytic hydrogenation/dehydrogenation/transfer hydrogenation

Abstract Driven by the compelling environmental and economic advantages of chemical upcycling of waste plastics, there is a growing push to develop highly efficient catalytic systems. These systems promise access to a wide spectrum of valuable chemical feedstocks, moving beyond the simple monomers obtained via traditional plastic recycling. This review specifically examines transition‐metal‐catalyzed hydrogenation, dehydrogenation, and transfer hydrogenation of depolymerized monomers derived from polyesters, polycarbonates, polyamides, and polyethylene. A key insight is the profound influence of ligands: multidentate coordination by phosphines, amines, pyridines, and carbenes provides distinct electronic and steric effects, which are instrumental in achieving the desired product formation.