Depolymerization of Waste Plastics to Monomers and Chemicals Using a Hydrosilylation Strategy Facilitated by Brookhart’s Iridium(III) Catalyst

Abstract

Plastic waste management is a major concern. While the societal demand for sustainability is growing, landfilling and incineration of waste plastics remain the norm and methods able to efficiently recycle these materials are desirable. Herein, we report the depolymerization, under mild conditions, of oxygenated plastics in the presence of hydrosilanes with the cationic pincer complex [Ir(POCOP)H(THF)][B(C6F5)4] (POCOP = 1,3-(tBu2PO)2C6H3)) as catalyst. The iridium catalyst, with a low loading (0.3–1 mol %), proves selective toward the formation of silyl ethers or the corresponding alkanes depending only on the reaction temperature. It is noteworthy that the depolymerization of real household waste plastics such as PET (from plastic bottles) and polylactic acid (PLA) from 3D printer filaments is not altered by the presence of dye or other plastic’s additives.