反应详情

174 g of 1-phenyl-3-methyl-pyrazol-5-one in 700 ml of acetic anhydride, with the addition of 6 g of p-toluenesulphonic acid, are heated to the boil under reflux for 6 hours. The solvent is then distilled off under a water-pump vacuum, the residue is dissolved hot in 2 l of 5% strength sodium hydroxide solution, the solution is clarified with 8 g of active charcoal, the filtrate is acidified with hydrochloric acid at room temperature and the crystalline precipitate is filtered off, washed with water and dried in vacuo at 40° C. 183 g of 1-phenyl-3-methyl-4-acetyl-pyrazol-5-one are obtained in the form of colourless crystal needles.

1. temperatureare heated to the boil
2. temperatureunder reflux for 6 hours
3. distillationThe solvent is then distilled off under a water-pump vacuum
4. dissolutionthe residue is dissolved hot in 2 l of 5% strength sodium hydroxide solution
5. customis acidified with hydrochloric acid at room temperature
6. filtrationthe crystalline precipitate is filtered off
7. washwashed with water
8. customdried in vacuo at 40° C