Novel succinimide-based ionic liquids as efficient and sustainable media for methanolysis of polycarbonate to recover bisphenol A (BPA) under mild conditions

In this paper, several succinimide-based ionic liquids (SIILs) were developed and structurally characterized. They were used as multifunctional and sustainable media for selective conversion of polycarbonate (PC) into bisphenol A (BPA) via methanolysis method. The catalytic behaviors of SIILs to the reaction, including the effects of SIIL structures, effects of reaction parameters, catalyst reusability, and interaction between SIIL and CH 3 OH were studied in detail. The [HDBU][Suc] comprising a 1,8-diazabicyclo[5.4.0]undec-7-ene cation and a succinimide anion exhibited superior performance compared to previous catalysts, and it afforded a complete depolymerization of PC with 96% BPA yield under mild conditions of 70 °C for 2 h in the absence of organic solvents and metal ions . The [HDBU][Suc] was easy to recycle and showed satisfactory reusability. Finally, a plausible mechanism for [HDBU][Suc]-catalyzed methanolysis of PC was presented in depth.