Direct Synthesis of Dimethyl Carbonate from Carbon Dioxide and Methanol at Room Temperature Using Imidazolium Hydrogen Carbonate Ionic Liquid as a Recyclable Catalyst and Dehydrant

Graphical We can do both : An imidazolium hydrogen carbonate ionic liquid can serve as both a recyclable catalyst (C) and dehydrant (D) for the direct synthesis of dimethyl carbonate (DMC) from CO 2 and CH 3 OH at room temperature (see scheme). A high conversion of CH 3 OH and excellent selectivity of DMC are obtained. The direct synthesis of dimethyl carbonate (DMC) from CO 2 and CH 3 OH was achieved at room temperature with 74 % CH 3 OH conversion in the presence of an imidazolium hydrogen carbonate ionic liquid ([C n C m Im][HCO 3 ]). Experimental and theoretical results reveal that [C n C m Im][HCO 3 ] can transform quickly into a CO 2 adduct, which serves as an effective catalyst and dehydrant. Its dehydration ability is reversible. The energy barrier of the rate-determining step for the DMC synthesis is only 21.7 kcal mol −1 . The ionic liquid can be reused easily without a significant loss of its catalytic and dehydrating ability.