An Efficient Catalyst System at Mild Reaction Conditions Containing Rare Earth Metal Complexes

An efficient rare earth metal complex-catalyzed cycloaddition reaction of CO2 with propylene oxide using Hdpza (di(2-pyrazyl)amine) as a N-donor ligand has been accomplished in good to excellent yields with high selectivity. The effects of different rare earth metal salts, ligands and reaction conditions were examined. Catalytic reaction tests demonstrated that the incorporation of ErCl3 and Hdpza can significantly enhance the catalytic reactivity of the TBAB (nBu(4)NBr, tetra-n-butyl ammonium bromide) towards cycloaddition reaction of CO2 and propylene oxide that produce cyclic carbonates under mild conditions without any co-solvent.