Imidazolinium Salts for the Carbonates Production from CO₂ and Epoxides

Novel imidazolinium based materials were prepared by modification of MCM-41 and characterized by elemental analysis, nitrogen sorption, thermogravimetric analysis, UV-Vis, and X-ray diffraction. The materials differed in the alkyl, or halide used (MeI, EtBr, PrI, BuBr, BuCl, and BnBr). The characterization methods confirmed the successful formation of desired materials containing iodide and bromide. In this research, the materials were examined as catalysts for the cycloaddition of carbon dioxide to styrene oxide to produce styrene carbonate. The influence of anion type and the length of the alkyl chain in the salt was discussed. The results show imidazolinium materials as efficient heterogeneous catalysts for the model reaction. Styrene carbonate was prepared with high selectivities in all cases. The highest conversion of styrene oxide (95%) was achieved using a material containing iodomethane (MCM-Im-MeI) under the following conditions: 1.2 MPa, 120 degrees C, solvent free. The catalysts were successfully reused without a significant decrease of their activity.