反应详情

300 g (1.22 mol) of 4-oxo-5-(phenylmethoxy)-4H-pyran-2-carboxylic acid was put into a flask and 5 1 of 33% NH4OH was carefully added with stirring. The reaction mixture was then stirred under reflux. After 3 hours, one additional liter of 33% NH4OH was added slowly. Stirring was continued for further 2 hours under reflux. The reaction solution was then evaporated until the product crystallized. The product was transferred back into the reaction flask and water added until a clear solution was obtained (approximately 5 1, pH 6.38). This solution was stirred vigorously while concentrated hydrochloric acid was added dropwise until a pH of 3 was obtained. The precipitated white product was removed by filtration, thoroughly washed with water and dried. Yield: 273 g (1.12 mol)=91.8%.

1. stirringThe reaction mixture was then stirred
2. temperatureunder reflux
3. stirringStirring
4. waitwas continued for further 2 hours
5. temperatureunder reflux
6. customThe reaction solution was then evaporated until the product
7. customcrystallized
8. additionadded until a clear solution
9. customwas obtained (approximately 5 1, pH 6.38)
10. additionwas added dropwise until a pH of 3
11. customwas obtained
12. customThe precipitated white product was removed by filtration
13. washthoroughly washed with water
14. customdried