Metal- and solvent-free synthesis of cyclic carbonates from epoxides and CO2 in the presence of graphite oxide and ionic liquid under mild conditions: A kinetic study

The cycloaddition reaction of carbon dioxide (CO2) with styrene oxide (SO) to produce styrene cyclic carbonate (SC) catalyzed by various imidazolium-based ionic liquids (ILs) in the presence of graphite oxide (GO) was studied under relatively mild conditions. It was revealed that the inherent Brّnsted acidic groups of the GO and halide anion of ILs exhibited an excellent synergistic effect in promoting the reaction. The presence of oxygen-containing functionalities on GO significantly enhanced the activity of the catalyst system. Furthermore, the decrease of the yield of SC was not noticeable after GO was reused five times, indicating that the catalyst system was highly efficient and stable. Moreover, the kinetics and mechanism of the reaction were also investigated via in situ infrared spectroscopy.