Theoretical study on the reaction of CO2 and 2-aminobenzonitrile to form quinazoline-2,4(1H,3H)-dione in water without any catalyst

Abstract

Development of efficient and green routes to convert CO₂ into value-added products is of great importance. Recently, we found that quinazoline-2,4(1H,3H)-diones and their derivatives could be synthesized from CO₂ and 2-aminobenzonitriles in water efficiently without a catalyst and excellent yields were obtained, while the reactions did not occur in organic solvents. In this work, using density functional theory (DFT) we conduct the first theoretical work to study the mechanism of the reactions in water. It is revealed that CO₂ reacts via carbonic acid (H₂CO₃) with 2-aminobenzonitrile to form the product. Formation of H₂CO₃ from CO₂ and water is the key for the reactions to proceed smoothly in water without a catalyst because of two reasons. First, H₂CO₃ reacts with 2-aminobenzonitriles more easily than CO₂ itself; second, H₂CO₃ can effectively promote the reaction by the synergistic action of its carbonyl O atom and one of the hydroxyl O atoms.