Efficient synthesis of cyclic carbonates from CO 2 under ambient conditions over Zn(betaine) 2 Br 2 : experimental and theoretical studies.

It is very interesting to synthesize high value-added chemicals from CO 2 under mild conditions with low energy consumption. Here, we report that a novel catalyst, Zn(betaine) 2 Br 2 , can efficiently promote the cycloaddition of CO 2 with epoxides to synthesize cyclic carbonates under ambient conditions (30 °C, 1 atm). DFT calculations provide important insights into the mechanism, particularly the unusual synergistic catalytic action of Zn 2+ , Br - and NR 4+ , which is the critical factor for the outstanding performance of Zn(betaine) 2 Br 2 . The unique features of the catalyst are that it is cheap, green and very easy to prepare.