A protic ionic liquid catalyzes CO₂ conversion at atmospheric pressure and room temperature: Synthesis of quinazoline-2,4(1H,3H)-diones

The chemical fixation of CO₂ under mild reaction conditions is of significance from a sustainable chemistry viewpoint. Herein a CO ₂-reactive protic ionic liquid (PIL), [HDBU⁺][TFE ^-], was designed by neutralization of the superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with a weak proton donor trifluoroethanol (TFE). As a bifunctional catalyst for simultaneously activating CO₂ and the substrate, this PIL displayed excellent performance in catalyzing the reactions of CO₂ with 2-aminobenzonitriles at atmospheric pressure and room temperature, thus producing a series of quinazoline-2,4(1H,3H)-diones in excellent yields. No pressure: The reaction of CO₂ with various 2-aminobenzonitriles was achieved at atmospheric pressure and room temperature by using the bifunctional protic ionic liquid [HDBU⁺][TFE^-], thus producing the title compounds in excellent yields. The ionic liquid serves as both the catalyst and solvent, and activates both CO₂ and the substrates simultaneously. DBU=1,8-diazabicyclo[5.4.0]undec-7-ene, TFE=trifluoroethanol.