Single-Site Bifunctional Catalysts for COX (X = O or S)/Epoxides Copolymerization: Combining High Activity, Selectivity, and Durability

  • Ren W
  • Liu Y
  • Xin A
 et al. 
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Abstract

Unprecedented activity (TOF > 270?000 h?1), high polymer selectivity (>99%), and excellent durability (TON > 600?000) were observed in the copolymerization of carbonyl sulfide (COS) and epoxides mediated by the single-site bifunctional chromium catalyst containing a Lewis acidic metal center and a sterically hindered organic base in a molecule, selectively producing the corresponding poly(thiocarbonate)s with completely alternating structure, high molecular weight, and narrow monodispersity. No oxygen?sulfur exchange reaction occurred even at an elevated temperature of 80 °C. Nevertheless, this catalyst was not efficient for CO2/epoxides copolymerization. The presence of CO2 completely inhibits the reactivity of COS. Contrarily, the corresponding Co(III) complex with the same ligand showed very low activity for COS/epoxides copolymerization but excellent activity (TOF > 13?000 h?1) for CO2/epoxides copolymerization at both ambient and high temperatures, affording the polycarbonates with >99% carbonate linkages and high molecular weight up to 467.0 kg/mol.
Unprecedented activity (TOF > 270?000 h?1), high polymer selectivity (>99%), and excellent durability (TON > 600?000) were observed in the copolymerization of carbonyl sulfide (COS) and epoxides mediated by the single-site bifunctional chromium catalyst containing a Lewis acidic metal center and a sterically hindered organic base in a molecule, selectively producing the corresponding poly(thiocarbonate)s with completely alternating structure, high molecular weight, and narrow monodispersity. No oxygen?sulfur exchange reaction occurred even at an elevated temperature of 80 °C. Nevertheless, this catalyst was not efficient for CO2/epoxides copolymerization. The presence of CO2 completely inhibits the reactivity of COS. Contrarily, the corresponding Co(III) complex with the same ligand showed very low activity for COS/epoxides copolymerization but excellent activity (TOF > 13?000 h?1) for CO2/epoxides copolymerization at both ambient and high temperatures, affording the polycarbonates with >99% carbonate linkages and high molecular weight up to 467.0 kg/mol.

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Authors

  • Wei Min Ren

  • Ye Liu

  • An Xiang Xin

  • Song Fu

  • Xiao Bing Lu

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