Merging sustainability with organocatalysis in the formation of organic carbonates by using CO<inf>2</inf> as a feedstock

The use of phenolic compounds as organocatalysts is discussed in the context of the atom-efficient cycloaddition of carbon dioxide to epoxides, forming useful cyclic organic carbonate products. The presence and cooperative nature of adjacent phenolic groups in the catalyst structure results in significantly enhanced catalytic efficiencies, allowing these CO2 fixation reactions to operate efficiently under virtually ambient conditions. The cooperative effect has also been studied by computational methods. Furthermore, when the cycloaddition reactions are carried out on a larger scale and under solvent-free conditions, further enhancements in activity are observed, combined with the advantageous requirement of reduced loadings of the binary organocatalyst system. The reported system is among one of the mildest and most effective metal-free catalysts for this conversion and contributes to a much more sustainable development of organic carbonate production; this feature has not been the main focus of previous contributions in this area. In a fix: A new organocatalytic method for organic carbonate synthesis is reported and allows attractive conditions (25 °C, 10 bar, no solvent) to be used (see picture). Cyclic carbonates produced from CO2 and epoxides are isolated in high yields. The mild nature of this process increases the overall process sustainability for this type of widely studied carbon dioxide fixation process. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.