Bifunctional Catalysts Based on m‐Phenylene‐Bridged Porphyrin Dimer and Trimer Platforms: Synthesis of Cyclic Carbonates from Carbon Dioxide and Epoxides. Issue 1 (4th November 2014)

• Record Type: Journal Article
• Authors: Maeda, Chihiro; Taniguchi, Tomoya; Ogawa, Kanae; Ema, Tadashi
• Is Part Of: Angewandte Chemie international edition. Volume 54:Issue 1(2015)
• Page Start: 134
• Page End: 138
• Publication Date: 2014-11-04
• Subjects: carbon dioxide fixation -- cyclic carbonates -- homogeneous catalysis -- porphyrinoids -- zinc; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201409729
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Highly active bifunctional diporphyrin and triporphyrin catalysts were synthesized through Stille coupling reactions. As compared with a porphyrin monomer, both exhibited improved catalytic activities for the reaction of CO2 with epoxides to form cyclic carbonates, because of the multiple catalytic sites which cooperatively activate the epoxide. Catalytic activities were carefully investigated by controlling temperature, reaction time, and catalyst loading, and very high turnover number and turnover frequency were obtained: 220 000 and 46 000 h −1, respectively, for the magnesium catalyst, and 310 000 and 40 000 h −1, respectively, for the zinc catalyst. Results obtained with a zinc/free‐base hybrid diporphyrin catalyst demonstrated that the Br − ions on the adjacent porphyrin moiety also function as nucleophiles. Abstract : Metal matters : Triporphyrin catalysts 1 Mg and 1 Zn efficiently catalyzed the reaction of epoxides and CO2 to form cyclic carbonates. The turnover number and turnover frequency reached 220 000 and 46 000 h −1, respectively, for 1 Mg and 310 000 and 40 000 h −1, respectively, for 1 Zn, thus representing the highest values reported to date for this type of reaction.