CO2 to carbonates
The conversion of carbon dioxide into valuable chemicals is attracting the attention of several research groups worldwide. The most investigated transformations are: carbon dioxide hydrogenation, carboxylation of epoxides, caboxylation of amines and alcohols, reduction reactions under electrochemical or photochemical conditions.
Of great industrial interest is the use of carbon dioxide to produce organic carbonates either cyclic or linear, such as ethylene carbonate (EC), propylene carbonate (PC), glycerol carbonate (GC) or dimethyl carbonate (DMC), diethyl carbonate (DEC), diallylcarbonate-DAC.
In this lecture the use of molecular, heterogenized, heterogeneous and organic catalysts for the synthesis of dialkyl carbonates (DMC, DEC, DAC) will be discussed and the role of water elimination for equilibrium displacement and catalyst protection will be highlighted.
In particular, the reaction mechanism will be demonstrated for two options.
The synthesis of cyclic carbonates via the oxidative carboxylation of olefins will be also discussed and the role of oxygen pressure on the yield of carbonate demonstrated.
The carboxylation of glycerol using either CO2 or urea will be presented and further reactions of GC briefly elucidated.