The greenhouse gas CO₂ can be used as an inexpensive, abundant, and renewable chemical feedstock. The reaction of CO₂ with epoxides (pictured) is particularly interesting in this context. It is an atom-economic reaction and an excellent example of green, sustainable chemistry. The obtained products, cyclic carbonates, have applications, e.g., as intermediates in organic synthesis, green solvents, electrolytes in lithium-ion batteries, polymer building blocks, and additives in cosmetics.

Thomas Werner, Leibniz Institute for Catalysis, Rostock, Germany, and colleagues have used phenol-functionalized phosphonium salts as an organocatalysts for the reaction of CO₂ with epoxides to give cyclic carbonates. The team used (2-hydroxyphenyl)diphenyl(propyl)phosphonium iodide as the catalyst for the solvent-free reaction of different substituted epoxides with CO₂ at room temperature to 80 °C.

Using this approach, various cyclic carbonates were prepared in excellent yields. Both terminal and more challenging internal epoxides were converted. The reaction has a good functional group tolerance and can be performed on a multi‐gram scale.

• Catalytic, kinetic and mechanistic insights into the fixation of CO₂ with epoxides catalyzed by phenol functionalized phosphonium salts,
  Yuya Hu, Zhihong Wei, Anna Frey, Christoph Kubis, Chang-Yue Ren, Anke Spannenberg, Haijun Jiao, Thomas Werner,
  ChemSusChem 2020.
  https://doi.org/10.1002/cssc.202002267