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

• Published in: ChemCatChem Vol. 4; no. 11; pp. 1752 - 1758
• Main Authors: Bai, Dongsheng, Duan, Shuhui, Hai, Long, Jing, Huanwang
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.11.2012; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: carbon dioxide fixation; cycloaddition; homogeneous catalysis; main group elements; porphyrinoids
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201200204

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. A healthy fixation: Several main group metalloporphyrin complexes are prepared and used in CO2 fixation in a “green” synthesis of cyclic carbonates from epoxides and CO2. The catalytic activity order of biomimetic metalloporphyrinoids was AlIII>MgII>SnIV>SnII, which is attributable to the Lewis acidity of the metal center.