Bifunctional Metalloporphyrins-Catalyzed Coupling Reaction of Epoxides and CO2 to Cyclic Carbonates

New catalysts of water soluble bifunctional metalloporphyrins M(TTMAPP)I-4(X) (M = Co, Fe, Mn, and Cr; X = OAc, CF3COO, CCI3COO, OTs, Cl, Br, and I) were synthesized and used-to catalyze the synthesis of cyclic carbonate through the coupling reaction of terminal epoxides and CO2. The effects of reaction temperature, various metals as the Lewis acidic center, counterions, and recycling of the catalysts were studied. 5,10,15,20-Tetra-(p-N,N,N-trimethylphenyl ammonium iodide)porphyrinium cobalt(III) acetate [Co(III)(TTMAPP)I-4(OAc)] was efficient in the coupling reaction of various terminal epoxides and CO2 at 353 K under 667 kPa of CO2 pressure without solvent and molar ratio of epoxide:catalyst = 1000. It gave a propylene carbonate yield of 95.4% within 5 h. At 298 K in the presence of 1 ml methanol with the molar ratio of epoxide:catalyst = 2000, it gave a propylene carbonate yield of 19.4% within 24 h. The catalyst could be recovered with diethyl ether and reused five times without significant loss of catalytic activity.