Accelerated Epoxy Deconstruction via Combined Catalytic Dehydrogenation with Base-Mediated Cleavage

Abstract Cured epoxy resins and their corresponding glass- and carbon-fiber-reinforced composites are widely used because of their high mechanical strength, chemical resistance, and long-term stability. However, their highly cross-linked structures render them inherently resistant to recycling, with landfilling and incineration remaining the predominant fate for end-of-life products. Existing chemical strategies for epoxy deconstruction are often limited by harsh conditions and poor selectivity. Conversely, strategies employing Ru-, Rh-, and Ni-based catalysts have been reported, offering comparatively mild reaction conditions and improved selectivity at the expense of reaction time, altogether highlighting the need for more efficient approaches. Recent mechanistic studies suggest that catalytic turnover becomes increasingly challenging when a single catalyst is required to mediate both the alcohol oxidation and α-C(sp3)–O(aryl) bond activation steps within cross-linked epoxy networks. Herein, we report an epoxy deconstruction strategy in which the catalyst is responsible for alcohol dehydrogenation, while subsequent α-C(sp3)–O(aryl) bond cleavage proceeds independently under aqueous basic conditions. By eliminating the dependence of C–O bond activation, the methodology enables efficient deconstruction of commercial epoxy resins for the recovery of bisphenol A (BPA) with improved reaction rates. Systematic optimization using Design-of-Experiments afforded up to 69% BPA recovery from a commercial epoxy sample, Airstone 760E/766H in 15 min. The method achieves a maximum turnover number (TON) of 81 and turnover frequency (TOF) of 974 h–1, exceeding the previously demonstrated values for Ru-, Rh-, and Ni-based catalytic systems (TONs of 54, 43, and 3.3, respectively; TOFs of 0.6, 1.8, and 0.1 h–1, respectively). The process was also successfully translated to gram-scale experiments, using 2-methyltetrahydrofuran as a solvent that can be sourced from renewable feedstocks. Overall, these findings demonstrate that decoupling alcohol dehydrogenation from bond cleavage provides an effective design principle for epoxy deconstruction, leading to a promising strategy for BPA recovery from epoxy thermosets.