Graphene oxide grafted hydroxyl-functionalized ionic liquid: A highly efficient catalyst for cycloaddition of CO2 with epoxides

A grafted 1-(2-hydroxyl-ethyl)-imidazolium-based ionic liquid (GO-HEIMBr) was developed via immobilizing 2-bromoethanol onto an imidazole-modified graphene oxide, which was prepared in a one-pot process. The physicochemical properties of GO-HEIMBr were characterized by atomic force microscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis, Fourier transform infrared spectroscopy, and elemental analysis. In the solvent-free cycloaddition reactions of CO2 with epoxides to cyclic carbonates, GO-HEIMBr exhibited excellent catalytic activities. A maximum yield of the target cyclic carbonate arrived at 99% using 0.35 mol% catalysts at 140 °C in 4 h. In addition, the catalyst could be easily recovered and reused for seven times without significant loss of activity. A possible catalytic mechanism was proposed for the cycloaddition over GO-HEIMBr.