Upcycling of Polystyrene to 1,2‐Disubstituted Oxygenated Aromatics Through Backbone Rearrangement and Oxidation Reactions

Abstract

Abstract Upcycling polystyrene (PS) into economically‐viable, industrially‐relevant single‐, and multi‐substituted oxygenated aromatic compounds is an attractive option to address the current unsustainable end‐of‐life of this high‐volume waste plastic. However, 1,2‐disubstituted oxygenated aromatics (e.g., phthalic anhydride), possessing a multi‐billion dollar annual market, have thus far been inaccessible from PS. This is due to unsurmountable steric constraints conferred by the polymer backbone hindering ortho‐functionalization of its pendant phenyl groups. Herein, to overcome this challenge, we report a strategy to convert PS directly into 1,2‐disubstituted aromatics, first by PS backbone rearrangement into polyindanes, followed by organocatalyzed aerobic oxidations. Our approach is applicable to mixed real‐life PS waste on multi‐gram scales, allowing convenient access to ortho ‐substituted aromatics used as catalysts, dyes, and drug precursors with different structural complexities previously inaccessible from PS. Furthermore, this versatile strategy was also applicable on PS‐like polymers such as poly(4‐methylstyrene), producing trimellitic, terephthalic, and isophthalic acids. This approach significantly expands the range of high‐value substituted aromatic products accessible from PS, further enhancing its utility as a feedstock in a circular economy.