Reaktion #530779

Reaktionsgleichung

1-phenyl-3-methyl-pyrazol-5-one

p-toluenesulphonic acid

acetic anhydride

→

1-phenyl-3-methyl-4-acetyl-pyrazol-5-one

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturare heated to the boil
2. 2
   Temperaturunder reflux for 6 hours
3. 3
   workup.DISTILLATIONThe solvent is then distilled off under a water-pump vacuum
4. 4
   workup.DISSOLUTIONthe residue is dissolved hot in 2 l of 5% strength sodium hydroxide solution
5. 5
   Sonstigeis acidified with hydrochloric acid at room temperature
6. 6
   Filtrationthe crystalline precipitate is filtered off
7. 7
   Waschenwashed with water
8. 8
   Sonstigedried in vacuo at 40° C

Vorschrift

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.

Quelle