Catalytic Strategies for the Cycloaddition of Pure, Diluted, and Waste CO2 to Epoxides under Ambient Conditions

Cyclic organic carbonates represent a relevant class of chemicals that can be prepared from CO2 by cycloaddition to epoxides. The application of efficient catalysts is crucial in allowing the cycloaddition reaction to proceed under very mild conditions of temperature, pressure, and CO2 concentration, thus resulting in a sustainable and carbon-balanced approach to CO2 conversion. This is particularly the case if impure waste CO2 could be employed as a feedstock. In this Review, we have critically analyzed the burgeoning literature on the cycloaddition of CO2 to epoxides with the aim to provide state-of-the-art knowledge on the catalysts that can convert CO2 to carbonates under ambient conditions. These have been systematically organized in families of compounds and critically scrutinized in terms of catalytic activity, availability and mechanistic features. Finally, we provide an overview on the catalytic systems able to function using diluted and impure CO2 as a feedstock.