Green chemistry strategies for CO2 valorization: Impact of substituents, solvents and catalysts on the cycloaddition of CO2 with epoxides forming cyclic carbonates.

A theoretical study of the reaction forming a cyclic carbonate from the cycloaddition of CO2 with a typical substituted epoxide, was carried out using first principles methodologies. As epoxide, we considered trans 1-(4-methoxyphenyl)-2-methoxy epoxyethane, exhibiting an optimal reactivity for cycloaddition with CO2. We found that this reaction exhibits a high energy barrier in the gas phase, thus requiring an activation method. We also investigated the role of various substituted epoxides (mono- and disubstituted) and solvent types, including nonpolar, polar protic, and polar aprotic solvents. Our findings revealed a preference for polar protic solvents, particularly water. Besides, we used catalysts, including Lewis bases and Lewis acids, to selectively favor one reaction pathway over the other. In sum, this study provides deep insights into the factors influencing the reactivity of this cycloaddition and identifies the most suitable solvents and catalysts to promote the reaction, with potential implications for the development of more efficient CO2 valorization processes.