A solid Zn complex catalyst for efficient transformation of CO2 to cyclic carbonates at mild conditions

A solid Zn Complex (Zn(HBA)2) with o-Hydroxybenzyl-Amine, which can be easily prepared by a one-step synthesis method, was exploited for the CO2 transformation to cyclic carbonates. The results demonstrated that Zn(HBA)2 is a high-efficiency catalyst in the coupling reaction between CO2 and epoxides under solvent-free conditions. Under mild conditions (80 °C, atmospheric CO2), epoxides with different substituents have been successfully transformed into the relevant cyclic carbonates with high yields and selectivity (>99%). The turnover frequency (TOF) was reached to 21,667 h−1 for the coupling of CO2 and epichlorohydrin (ECH) into chloropropene carbonate (CPC) under 120 °C and a 1.8 MPa of CO2 pressure within 3 h. This catalyst is capable of recovering and reusing by simple filtration. The catalytic mechanism of Zn(HBA)2 for the cycloaddition reaction was proposed.