The conversion of carbon dioxide (CO2), a notorious green-house gas, to value-added chemicals has received growing interest in the petrochemical industrial recently. Production of cyclic carbonate from CO2 and epoxides is one of the promising ways for effective utilization CO2. Herein, we studied the reaction of CO2 and ethylene oxide over a fine-tuned Lewis acid paddlewheel unit, heterometallic Mo/Rh trifluoroacetate [MoRh(O2CCF3)4], by using density functional theory. The reaction is proposed to proceed two pathways, namely concerted and stepwise. In the concerted pathway, the reaction occurs in the single simultaneous step of the ethylene oxide ring-opening and the CO2 cyclization with the activation barrier of 39.1 kcal/mol. For the stepwise pathway, the reaction starts with the ring-opening of ethylene oxide resulting in an intermediate with the activation energy of 20.8 kcal/mol. Consequently, this intermediate is inserted by CO2 yielding the ethylene carbonate with an activation energy of 23.7 kcal/mol. Based on the energetics of the reactions, it can be concluded that the production of ethylene carbonate from carbon dioxide and ethylene oxide over the Mo/Rh trifluoroacetate catalyst preferably occurs via the stepwise pathway.

Cycloaddition reaction of carbon dioxide and ethylene oxides over heterometallic paddlewheel carboxylates: A mechanistic study

247th National Meeting (2014)

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