Metal-free imidazolium hydrogen carbonate ionic liquids as bifunctional catalysts for the one-pot synthesis of cyclic carbonates from olefins and CO2

A direct route for the synthesis of cyclic carbonates from olefins and CO2 has been achieved by using imidazolium hydrogen carbonate ionic liquids ([C(n)C(m)Im][HCO3]) as bifunctional catalysts in the absence of a solvent. [C(n)C(m)Im][HCO3] can convert into a carbene-CO2 adduct spontaneously. The HCO3- anion and carbene-CO2 can serve as catalysts for olefin epoxidation and CO2 cycloaddition, respectively, which obviously simplifies the synthesis of cyclic carbonates. The reaction proceeds quite well under mild conditions. This cheap and simple method can be applied to various olefins with good to excellent yields of cyclic carbonates. The catalyst can be easily recycled at least four times without significantly losing its catalytic activity.

在无溶剂的情况下，使用碳酸氢咪唑鎓离子液体（[C(n)C(m)Im][HCO₃]）作为双功能催化剂，实现了从烯烃和二氧化碳直接合成环状碳酸酯的方法。[C(n)C(m)Im][HCO₃]能自发地转化为卡宾 - 二氧化碳加合物。HCO₃⁻阴离子和卡宾 - 二氧化碳可分别作为烯烃环氧化和二氧化碳环加成的催化剂，这明显简化了环状碳酸酯的合成。该反应在温和条件下进行得很好。这种廉价且简单的方法可应用于各种烯烃，环状碳酸酯的产率良好至优异。该催化剂至少可轻松循环使用四次，且不会显著丧失其催化活性。