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 CO₂‐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.