Synthesis of cyclic carbonate from carbon dioxide and diols over metal acetates

Different metallic acetates were used as the catalysts to synthesize cyclic carbonates from carbon dioxide and diols in the presence of acetonitrile. In the course of reaction, acetonitrile acted as not only the solvent but also the dehydrating reagent to eliminate the effect of the water produced from the reaction. Thus, the thermodynamic equilibrium was shifted and the yield of cyclic carbonates was improved. Using 1,2-propylene glycol as the reactant to screen the catalysts, it was found that anhydrous zinc acetate possessed the highest catalytic activity. The reaction of carbon dioxide and diols was systemically studied over anhydrous zinc acetate. The results showed that the yields of five-membered cyclic carbonates were obviously higher than that of six-membered cyclic carbonates and the yield of 1,2-propylene carbonate was the highest. Using 1,2-propylene glycol as the reactant and anhydrous zinc acetate as the catalyst, the reaction conditions were optimized as 1,2-propylene glycol 100 mmol, acetonitrile 10 mL, catalyst 2.5 mmol, reaction pressure 10 MPa, reaction temperature 170°C, and reaction time 12 h. Under the optimal conditions, the yield of 1,2-propylene carbonate was 24.2% and the conversion of 1,2-propylene glycol was 38.9%.