La–Mg mixed oxide as a highly basic water resistant catalyst for utilization of CO<SUB>2</SUB> in the synthesis of quinazoline-2,4(1H,3H)-dione

The synthesis of quinazoline-2,4(1H,3H)-dione was done by direct utilization of CO<SUB>2</SUB> in the cyclization of 2-aminobenzonitrile (2-ABN) using lanthanum magnesia mixed oxide (La–Mg MO) as a strong basic catalyst under mild reaction conditions in water. It gave a conversion of ∼92% with 100% selectivity at 140 °C in 14 h. La–Mg MO was prepared by hydrothermal method using urea as homogeneous precipitating agent. The catalyst was characterized by different analytical techniques like BET, XRD, FT-IR, SEM, and TGA, and the basicity by CO<SUB>2</SUB>-TPD and acidity by NH<SUB>3</SUB> TPD. Various reaction parameters were studied to predict the reaction mechanism and kinetics. The reaction follows the Langmuir–Hinshelwood–Hougen–Watson (LHHW) type kinetics model with an apparent activation energy of 23.3 kcal mol<SUP>−1</SUP>. The catalyst was recycled three times with an insignificant change in activity. The overall process is clean and green

Carbon dioxide mediated novel synthesis of quinazoline-2,4(1H,3H)-dione in water

A novel, efficient, and scalable CO<SUB>2</SUB> mediated synthesis of quinazoline-2,4(1H,3H)-dione was developed by a simple cyclization of 2-aminobenzonitrile with DMF in water as the solvent. This is the first report of its kind. DMF was used as the necessary carbon source in the synthesis of quinazoline-2,4(1H,3H)-dione. This synthetic protocol is very efficient; it gives >99% conversion with excellent selectivity. The product was isolated by filtration because of the highly insoluble nature of quinazoline-2,4(1H,3H)-dione in water. The co-product, dimethyl amine, also has industrial importance, and the CO<SUB>2</SUB> that is used can be recycled. This protocol has wide-spread applications in the syntheses of benzimidazole and benzothiazole

Carbon Dioxide Mediated Novel Synthesis of Quinazoline-2,4(1<i>H</i>,3<i>H</i>)‑dione in Water

A novel, efficient, and scalable CO₂ mediated synthesis of quinazoline-2,4­(1<i>H</i>,3<i>H</i>)-dione was developed by a simple cyclization of 2-aminobenzonitrile with DMF in water as the solvent. This is the first report of its kind. DMF was used as the necessary carbon source in the synthesis of quinazoline-2,4­(1<i>H</i>,3<i>H</i>)-dione. This synthetic protocol is very efficient; it gives >99% conversion with excellent selectivity. The product was isolated by filtration because of the highly insoluble nature of quinazoline-2,4­(1<i>H</i>,3<i>H</i>)-dione in water. The co-product, dimethyl amine, also has industrial importance, and the CO₂ that is used can be recycled. This protocol has wide-spread applications in the syntheses of benzimidazole and benzothiazole