Dongsheng Bai

Carbon Dioxide Fixation by Cycloaddition with Epoxides, Catalyzed by Biomimetic Metalloporphyrins

Several biomimetic metalloporphyrin complexes (M(TPP)XY; in which TPP=meso‐porphyrin; M=MgII, AlIII, SnII, or SnIV; X=OAc, F, Cl, Br, I, OTf, or none; and Y=Cl, Br, I, OTf, or none) were prepared, characterized, and used effectively in the “green” synthesis of cyclic carbonates from epoxides and CO2. The catalytic systems of Mg(TPP)/tetrabutylammonium iodide and Al(TPP)Cl/phenyltrimethyl ammonium tribromide can initiate the cycloaddition of epoxides and CO2 at room temperature to generating cyclic carbonates in excellent yield. Chlorophyll A is shown to induce enantioselectivity of racemic propylene oxide. All reactions displayed excellent selectivity to cyclic carbonate without polycarbonate and other by‐products. Chloropropylene carbonate is shown to be obtained under CO2 bubbling conditions catalyzed by Al(TPP)Cl/phenyltrimethylammonium tribromide. The catalytic order of activity for biomimetic metalloporphyrins is AlIII>MgII>SnIV>SnII. These phenomena are explained with respect to the Lewis acidity of metal center in metalloporphyrins.

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

Abstract New catalysts of water soluble bifunctional metalloporphyrins M(TTMAPP)I 4 (X) (M = Co, Fe, Mn, and Cr; X = OAc, CF 3 COO, CCl 3 COO, OTs, Cl, Br, and I) were synthesized and used to catalyze the synthesis of cyclic carbonate through the coupling reaction of terminal epoxides and CO 2 . 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 CO 2 at 353 K under 667 kPa of CO 2 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.

Aerobic oxidative carboxylation of olefins with metalloporphyrin catalysts

Dioxo(tetraphenylporphyrinato)ruthenium(VI) and quaternary onium salt were successfully developed as catalysts to initiate a three component reaction of olefin, O2, and CO2 at ambient temperature under low pressure. The reaction can be carried out under solvent-free or solvent conditions. Styrene carbonate was obtained in 76% yield with 100% selectivity using 4 mol% of catalyst under optimized conditions.