LAUSR

Abstract The efficient capture and conversion of carbon dioxide (CO2) has attracted considerable attention for synthesizing valuable chemicals. In this work, we reported an effective method for the synthesis of various carbamates from amines, alcohol, and CO2 in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Two pathways were proposed for this reaction process. One pathway was that the protic ionic liquids (ILs), [DBUH][RO], could activate CO2 to produce [DBUH][ROCO2] at mild conditions. The nucleophilic nitrogen atom of amines attacked the carbon atom of [ROCO2]− to form the [NHCO2]−. Another way of the reaction was that the mixture of DBU/amines directly transformed into ILs by exposing to CO2, which was followed by the reaction with electrophile of CH2Br2 to generate the isocyanate at 333.2 K. Moreover, DBU could be easily recovered and reused. This protocol provides a feasible methodology for the production of carbamates and extends the chemical utilization of CO2.