Highly Active and Robust Metalloporphyrin Catalysts for the Synthesis of Cyclic Carbonates from a Broad Range of Epoxides and Carbon Dioxide

Chihiro Maeda, Junta Shimonishi, Ray Miyazaki, Jun Ya Hasegawa, Tadashi Ema

Research output: Contribution to journalArticlepeer-review

115 Citations (Scopus)

Abstract

Bifunctional metalloporphyrins with quaternary ammonium bromides (nucleophiles) at the meta, para, or ortho positions of meso-phenyl groups were synthesized as catalysts for the formation of cyclic carbonates from epoxides and carbon dioxide under solvent-free conditions. The meta-substituted catalysts exhibited high catalytic performance, whereas the para- and ortho-substituted catalysts showed moderate and low activity, respectively. DFT calculations revealed the origin of the advantage of the meta-substituted catalyst, which could use the flexible quaternary ammonium cation at the meta position to stabilize various anionic species generated during catalysis. A zinc(II) porphyrin with eight nucleophiles at the meta positions showed very high catalytic activity (turnover number (TON)=240 000 at 120 °C, turnover frequency (TOF)=31 500h-1 at 170°C) at an initial CO2 pressure of 1.7MPa; catalyzed the reaction even at atmospheric CO2 pressure (balloon) at ambient temperature (20°C); and was applicable to a broad range of substrates, including terminal and internal epoxides. In a fix! Bifunctional metalloporphyrins act as catalysts for the formation of cyclic carbonates from epoxides and CO2 (see scheme). A comparison of the catalytic activities shows the superior performance of meta-substituted catalysts. A robust zinc(II) porphyrin with eight nucleophiles at the meta positions shows the highest catalytic activity and a broad substrate scope, including terminal and internal epoxides.

Original languageEnglish
Pages (from-to)6556-6563
Number of pages8
JournalChemistry - A European Journal
Volume22
Issue number19
DOIs
Publication statusPublished - May 4 2016

Keywords

  • carbon dioxide fixation
  • cyclic carbonates
  • epoxides
  • homogeneous catalysts
  • porphyrinoids

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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