β-Cyclodextrin/Quaternary Ammonium Salt as an Efficient Catalyst System for Chemical Fixation of CO₂.

The environmental friendly biomaterial β-cyclodextrin (β-CD) was used for the synthesis of cyclic carbonates from CO₂ with epoxides in the presence of quaternary ammonium salts as co-catalyst. The factors affecting the activity of this binary catalyst system, such as reaction temperature, time, CO₂ pressure and the mole ratio of reactants, were investigated systematically. The excellent yield of cyclic carbonate (100%) was obtained at 130 °C, 3 MPa after 5 h with the catalyst system of β-CD/tetrabutylammonium bromine (TBABr). The catalyst system of β-CD/TBABr can also be applied to a wide substrates of epoxides with good to excellent yield and high selectivity (>99%). Recyclable ability of β-CD/TBABr can also be detected and there was no significant decline in activity after five recycles. Finally, reaction mechanism was proposed based on the reaction results and literatures.