Cation-driven poly(ionic liquid)s as highly efficient and selective catalysts for ethyl methyl carbonate synthesis

Ethyl methyl carbonate (EMC) is mainly prepared via the transesterification between ethanol (EtOH) and dimethyl carbonate (DMC) using alkaline catalysts. However, reported catalysts exhibit deactivation, environmental pollution, and low efficiency. Herein, we prepared a heterogeneous catalyst based on phenolate anion ([PhO] − )-functionalized poly(ionic liquid)s (PILs). Catalytic performance improved via rational PIL framework design with quaternary ammonium cations, which co-tuned polymer swelling and [PhO] − electronegativity. Among the series, [N 3 PIL][PhO], the most active catalyst, featuring high swelling degree and strong [PhO] − electronegativity, was validated by experiments and DFT calculations. Under optimized conditions (DMC/EtOH molar ratio = 3, catalyst dosage = 5 wt%, reaction time = 5 h, temperature = 100°C), EMC yield and selectivity reached 53.57% and 95.75%, respectively. This work offers a viable strategy to overcome conventional catalyst drawbacks and new insights for efficient heterogeneous EMC synthesis catalyst design.