Imidazolium and pyridine bifunctionalized hypercrosslinked polymers as efficient and recyclable catalysts for CO2 cycloaddition

Converting CO2 into precious chemicals is considered to be a fundamental and effective tool for controlling the abundant CO2 emitted. One of the most compelling methods for CO2 conversion is the synthesis of cyclic carbonates by cycloaddition of CO2 with epoxides. However, the development of materials with specific functionalities for CO2 capture and conversion is still considered to be a significant challenge. Herein, a novel imidazolium salts and pyridine skeleton bifunctionalized hypercrosslinked polymers were prepared by FeCl3-catalyted Friedel-Crafts alkylation reaction. Various analytical techniques were used to investigate the properties of the catalysts. The bifunctionalized heterogeneous catalysts exhibited outstanding catalytic performances for CO2 cycloaddition under mild conditions with an excellent yield of up to 99 %. Besides, the catalyst could bear various epoxides and no significant loss of activity after 6 cycles. The properties of metal-free, solvent-free, cocatalyst-free, easy-to-prepare, mild conditions, facility separation and recyclability make the bifunctionalized hypercrosslinked polymers useful for CO2 cycloaddition. A novel imidazolium and pyridine bifunctionalized HCPs-NHC were prepared by Friedel-Crafts alkylation reaction, and the HCPs-NHC were considered as efficient catalyzes toward CO2 conversion associated with the properties of metal-free, solvent-free, cocatalyst-free, easy preparation, inexpensive, mild conditions, recovery and recyclability. [Display omitted] •A novel imidazolium and pyridine skeleton bifunctionalized hypercrosslinked polymers was prepared by Friedel-Crafts reaction.•The catalysts exhibited outstanding catalytic performances for CO2 cycloaddition under mild conditions with excellent yield.•The HCPs-NHC has the advantages of metal-free, solvent-free, cocatalyst-free, easy preparation, recovery and recyclability.•This work affords an approach for converting CO2 into cyclic carbonates to help address the increasing greenhouse gases.