Efficient Transformation of CO₂ into Quinazoline-2,4(1<i>H</i>,3<i>H</i>)-diones by Bifunctional Phthalimide-Based Ionic Liquids under Mild Conditions

Carbon dioxide (CO2) capture and utilization have garnered significant attention in recent years. Carboxylative coupling of CO2 with 2-aminobenzonitriles is an important pathway to accomplish CO2 utilization. However, the catalytic activity is limited under mild conditions, especially under normal pressure. Some innovative phthalimide-based ionic liquids are developed in this work for the efficient transformation of CO2 into quinazoline-2,4(1H,3H)-diones. Under atmospheric pressure and 70 °C, the product yield reaches 99.7% within 8 h in the presence of [Pth][DBUH], which is superior to most of the previously reported catalysts. The superior catalytic performance is greatly related to the cooperation of the cation and the anion, which is confirmed by experimental measurements and theoretical calculations. The strong basicity and effective CO2 absorption capacity result in the superior activity of [Pth][DBUH].