Abstract
We developed various metalloporphyrins as bifunctional catalysts for the synthesis of cyclic carbonates from epoxides and CO2 under solvent-free conditions. The structures of the bifunctional catalysts were optimized step by step. As a result, a Zn porphyrin bearing eight nucleophiles at the meta positions showed a high turnover number (TON = 240,000) at 120°C at 1.7 MPa CO2 and catalyzed the reaction even at atmospheric CO2 pressure (balloon) at ambient temperature (20°C). Triporphyrin catalysts showed very high catalytic activity: TON = 220,000 and TOF = 46,000 h-1 for the Mg triporphyrin, and TON = 310,000 and TOF = 40,000 h-1 for the Zn triporphyrin. The high catalytic activity of these bifunctional catalysts was due to the cooperative action of Mg2+ or Zn2+ and Br- and a conformational change (induced-fit) of the quaternary ammonium cation.
Original language | English |
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Pages (from-to) | 814-823 |
Number of pages | 10 |
Journal | Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry |
Volume | 74 |
Issue number | 8 |
DOIs | |
Publication status | Published - 2016 |
Keywords
- Bifunctional catalyst
- Carbon dioxide
- Cooperative effect
- Cyclic carbonate
- Epoxide
- Porphyrin
- Synergetic effect
- Turnover frequency
- Turnover number
ASJC Scopus subject areas
- Organic Chemistry