反应详情

To a solution of 3-amino-4-benzoyl-5--nitrobenzoic acid (100 g) in a mixture of conc. sulfuric acid (875 ml) and water (280 ml) is dropwise added a solution of sodium nitrite (45.0 g) in water (280 ml), while stirring at -5° C to 0° C. After additional stirring at -5° C to 0° C for about 15 minutes, the resulting diazoniumsolution is heated on a steam bath for 2-3 hours until the nitrogen evolution has ceased. After cooling, the resulting precipitate is collected by filtration and washed with water. After drying and recrystallization twice from aqueous ethanol, 4-benzoyl-3-hydroxy-5-nitrobenzoic acid is obtained as a monohydrate with a melting point of 264° -266° C.

1. stirringAfter additional stirring at -5° C to 0° C for about 15 minutes
2. temperaturethe resulting diazoniumsolution is heated on a steam bath for 2-3 hours until the nitrogen evolution
3. temperatureAfter cooling
4. filtrationthe resulting precipitate is collected by filtration
5. washwashed with water
6. customAfter drying
7. customrecrystallization twice from aqueous ethanol