Dual-ionic imidazolium salts to promote synthesis of cyclic carbonates at atmospheric pressure

Novel dual-ionic imidazolium salts are shown to display excellent catalytic activity for cycloaddition of carbon dioxide and epoxides under room temperature and atmospheric pressure (0.1 MPa) without any solvent and co-catalyst leading to 96.1% product yield. It can be reused five times to keep the product yield over 90%. These intriguing results are attributed to a new reaction mechanism, which is supported by theoretical calculations along with the measurements of C-13 NMR spectrum and Fourier transform infrared spectroscopy (FT-IR). The excellent catalytic activity can be traced to a CO2-philic group along with an electrophilic hydrogen atom. Our work shows that incorporation of CO2-philic group is an feasible pathway to develop the new efficient ionic liquids. (c) 2021 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.

Automated summary

We report a novel dual-ionic imidazolium salt catalyst that exhibits efficient catalytic activity for the cycloaddition of carbon dioxide and epoxides under environmentally friendly conditions, without the need for solvent and co-catalyst, with a yield as high as 96.1%. The catalyst can be reused multiple times with a yield maintained above 90%. Theoretical calculations and experimental measurements support a new reaction mechanism involving a CO2-philic group and an electrophilic hydrogen atom in the catalyst. Our findings suggest that incorporating CO2-philic groups is a feasible approach to develop new efficient ionic liquids.