Insight into catalytic contribution of non-halogen cation and anion for CO2 conversion into cyclic carbonate

Non-halogen ionic liquids are considered efficient catalyst for CO 2 conversion into cyclic carbonates. In this work, six carboxylic acid ionic liquids with different types and sizes of cations are designed and synthesized to systematically investigate the catalytic contribution of the non-halogen cation and anion for CO 2 conversion into cyclic carbonate. The result shows that the anion could improve the catalytic activity by improve the basicity of ionic liquids, and the cation that has a weak interaction with anion is more conducive for the reactivity. Further, the reaction mechanism is deeply studied by using the optimized [P 4444 ][IsoNic]: two reaction intermediates are captured by In-situ infrared, combined with DFT calculation, the anion directly inducing ring-opening mechanism is proposed. This work provides an in-depth understanding of catalytic contribution of non-halogen ionic liquids used in cycloaddition reaction.