Highly Active and Readily Accessible Proline-Based Dizinc Catalyst for CO₂ /Epoxide Copolymerization

Area of Science:

• Catalysis
• Polymer Chemistry
• Materials Science

Background:

• Developing sustainable CO2-based materials is crucial.
• Efficient catalysts for CO2 and epoxide copolymerization are needed.
• Catalysts should offer high activity, low CO2 pressure tolerance, and polymer control.

Purpose of the Study:

• To report a novel chiral zinc catalyst for polycarbonate synthesis.
• To evaluate catalyst performance in terms of activity, selectivity, and stereocontrol.
• To gain mechanistic insights into the copolymerization process.

Main Methods:

• Isolation of a chiral zinc catalyst from commercial sources.
• Alternating copolymerization of CO2 and cyclohexene oxide.
• Characterization of polymer tacticity and catalyst structure/spectroscopy.

Main Results:

• The chiral zinc catalyst was isolated in 97% yield.
• Selective polycarbonate production from cyclohexene oxide under 1 bar CO2 at >50°C.
• High turnover numbers (TONs) of 1684 and turnover frequencies (TOFs) up to 149 h⁻¹ at 80°C.
• Production of isotactic-enriched polycarbonate (Pm = 65%).

Conclusions:

• The novel chiral zinc catalyst is highly effective for CO2-based polycarbonate synthesis.
• The catalyst operates efficiently under mild conditions with low CO2 pressure.
• Structural and spectroscopic studies provided insight into the active dinuclear species and reaction mechanism.