Advancing Ruthenium Catalyzed C–O Bond Disconnection in Thermoset Epoxy Resins

Cross-linked epoxy resins and their fibre-reinforced composites are extensively employed for diverse applications, yet their robust network structures make recycling particularly challenging.¹ Current chemical recycling methods often require severe reaction conditions or suffer from limited efficiency, motivating the development of alternative deconstruction strategies.² Herein, we describe an approach that separates alcohol dehydrogenation from C(sp³)–O bond cleavage during epoxy resin depolymerisation. In contrast to previously reported systems that depend on a single catalyst to promote both transformations, Ru–MACHO employed for the acceptorless alcohol dehydrogenation step, while C–O bond cleavage was achieved independently under basic conditions. Mechanistic investigations indicate that metal–phenoxide species may hinder the performance of conventional Ru–TRIPHOS-based systems,³ and that bypassing this pathway leads to improved reaction efficiency. Optimization through a design-of-experiments (DoE) strategy enabled the recovery of up to 69% bisphenol A from a commercial epoxy resin sample within 90 min using 2-methyltetrahydrofuran as a greener solvent.