Mn(I)-Complex Catalyzed Upcycling of Polyethylene Terephthalate to α-Hydroxy Carboxylic Acids.

Abstract

The chemical upcycling of poly(ethylene terephthalate) (PET) waste into value-added products presents a promising strategy to address global plastic pollution. Here, we report a manganese-catalyzed, one-pot approach for tandem PET depolymerization and acceptorless dehydrogenative coupling (ADC) to selectively produce α-hydroxycarboxylic acids (α-HCAs), including glycolic, lactic, and higher-value derivatives, along with terephthalic acid (TPA) and H₂ gas. Employing bench-stable (PNP)Mn(I)-pincer complexes, this cascade process operates under mild conditions (120-140 °C) and accommodates a broad range of primary alcohol coupling partners, enabling the synthesis of valuable biodegradable polymer precursors (glycolic and lactic acid) and higher α-HCAs. Notably, the system exhibits exceptional tolerance to common plastic additives and requires no energy-intensive pretreatment, achieving near-quantitative TPA recovery and significant H₂ evolution. This work demonstrates how base-metal catalysis can bridge plastic waste remediation and sustainable chemical synthesis, offering a practical pathway toward circular polymer economies.