Highly Efficient and Sustainable Chemical Fixation of Carbon Dioxide to Quinazoline-2,4(1H,3H)-diones by Hydroxybenzoic Functionalized Supported Ionic Liquids

Introduction: Cyclization reaction of CO2 and 2-aminobenzonitrile is of significance because of its important application in chemical synthesis. Consequently, the development of eco-friendly and highly efficient catalysts has garnered significant interest. Method: In the current research, supported ionic liquids were synthesized via a sol-gel method. The study involves a systematic study of their characterizations, with the intention of applying them as heterogeneous catalysts for the CO2 cyclization reaction. Results: After anion exchange to enrich active functional anions, the resulting supported ionic liquids behaved as high-efficiency heterogeneous catalysts for additive-free CO2 cyclization at 60 °C and 0.1 MPa CO2. Notably, ILC7H5O3@SiO2 exhibited high catalytic activity for the CO2 cyclization of various substituted 2-aminobenzonitriles. The products are obtained with high purity without the need for additional purification steps. Additionally, ILC7H5O3@SiO2 could serve as a durable and recoverable heterogeneous catalyst for the reaction, exhibiting excellent reusability for up to five consecutive runs without significant loss of catalytic activity, thereby demonstrating its practical and sustainable nature. Discussion: Compared to conventional protocols, this catalyst offers advantages such as high catalytic efficiency, superior yields, inexpensive nature, operational simplicity, reusability, and environmental benignity. Conclusion: This work highlights the significance of nanostructured catalysts in advancing green synthetic strategies, providing novel insights for the development of heterogeneous catalysts that facilitate efficient CO2 utilization.