Glycolysis of PET Using 1,3-Dimethylimidazolium-2-Carboxylate as an Organocatalyst

The use of 1,3-dimethylimidazolium-2-carboxylate as an organocatalyst for the glycolysis of waste PET, poly­(ethylene terephthalate), is reported for the first time. Postconsumer PET was completely depolymerized in less than 1 h at 180 °C with up to 60% of bis(2-hydroxyethyl terephthalate) (BHET) recovered by precipitation after cooling the reaction mixture. Under comparable conditions, the basic ionic liquid, 1,3-dimethylimidazolium acetate, was a significantly less effective catalyst suggesting that catalysis occurs through formation of a nucleophilic N-heterocyclic carbene.