Bifunctional catalysts for the CO2 fixation: Structural optimization to maximize the synergetic effect

Research output: Contribution to journalArticle

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 languageEnglish
Pages (from-to)814-823
Number of pages10
JournalYuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry
Volume74
Issue number8
Publication statusPublished - 2016

Keywords

  • Bifunctional catalyst
  • Carbon dioxide
  • Cooperative effect
  • Cyclic carbonate
  • Epoxide
  • Porphyrin
  • Synergetic effect
  • Turnover frequency
  • Turnover number

ASJC Scopus subject areas

  • Organic Chemistry

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