Chemical fixation of carbon dioxide into cyclic carbonates by multi-hydroxyl carboxylic acid ionic liquids under atmospheric pressure

Transformation CO2 to valuable chemical products is a favorable way for reducing CO2 emissions. However, the developed methodologies usually suffer from harsh reaction conditions. In this work, a series of ionic liquids featuring anions with multiple hydroxyl carboxylic acid moieties (MHCAIL1-5) were facilely synthesized, which exhibiting remarkable catalytic activity in conversion CO2 and various epoxides to cyclic carbonates without metal, co-catalysts, solvents and halogen under atmospheric pressure. The hydroxyl groups and carboxylate anion in ILs serve as hydrogen bond donors and nucleophiles to activate epoxides, ensuring exceptional conversion. Notably, the catalytic performance of MHCAIL-5 resulted in 99 % conversion of epichlorohydrin and 99 % selectivity of chloropropene carbonate at 80 celcius within 3 h at atmospheric pressure. Proposed mechanism has been postulated according to NMR, FT-IR and Mass spectrometry results. Furthermore, due to the high thermodynamic and chemical stability of ionic liquids, this catalytic system demonstrated excellent recyclability.