From Solvent to Catalyst: In Situ Amino Acid‐Like Species Enable PET Upcycling Without Added Catalysts

Abstract Chemical recycling of polyethylene terephthalate (PET) offers a promising route to value‐added chemical production, yet conventional methods typically demand harsh conditions and dedicated catalysts. Here, we report a bioinspired strategy that exploits the intramolecular acid‐base synergy of amino acids for efficient PET depolymerization. Alanine functions as a bifunctional organocatalyst, enabling complete PET esterolysis by dimethyl carbonate within 3 h at 180 °C to afford dimethyl terephthalate (98%) and ethylene carbonate (80%). Extending this concept, trace water in N‐ methyl ‐2‐pyrrolidone induces in situ generation of 4‐(methylamino)butyric acid, which emulates amino acid bifunctionality and enables catalyst‐free depolymerization under identical conditions. Density functional theory (DFT) calculations reveal an intramolecular dual‐site acid‐base mechanism, where –COO − and –NH 2 ⁺ groups cooperatively activate methanol and PET carbonyls through hydrogen‐bonded cyclic transition states, lowering the barrier by ∼29 kcal mol −1 . The method extends broadly to polyesters and polycarbonate, while establishing a transferable design paradigm that translates catalytic principles from nature into organocatalyst and solvent design, underscoring solvent molecular design as a general lever for sustainable catalysis and plastic upcycling.