Reaktion #55558

Reaktionsgleichung

Jones reagent

1-(m-trifluoromethylphenyl)pyrazole-4-carboxaldehyde

Jones reagent

sulfuric acid

Jones reagent

acetone

→

1-(m-trifluoromethylphenyl)pyrazole-4-carboxylic acid

Ausbeute 89.0%

Lösungsmittel

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeErlenmeyer flask, fitted with a thermometer and a magnetic stirrer
2. 2
   workup.ADDITIONcontaining a solution of 8.3 g
3. 3
   workup.DISSOLUTIONby dissolving 26.7 g
4. 4
   Temperaturis cooled by an ice water bath
5. 5
   Temperaturunder cooling, for 15 minutes
6. 6
   Sonstigeafter which time it is quenched with a large volume of water
7. 7
   workup.WAITto stand at room temperature for about 3 hours
8. 8
   SonstigeThe resultant precipitated solids
9. 9
   Filtrationare then filtered
10. 10
    Waschenwashed successively with water and petroleum ether
11. 11
    SonstigeThe solvent is then removed under vacuum

Vorschrift

Into a 500 ml. Erlenmeyer flask, fitted with a thermometer and a magnetic stirrer, containing a solution of 8.3 g. (0.0346 M.) of 1-(m-trifluoromethylphenyl)pyrazole-4-carboxaldehyde in 300 ml. of acetone is slowly added 20.0 ml. of Jones reagent (prepared by dissolving 26.7 g. of chromium trioxide in 23.0 ml. of concentrated sulfuric acid and then diluting to 100 ml. with water), the addition of the Jones reagent being effected while the solution is cooled by an ice water bath. Upon completion of the addition of the Jones reagent, the reaction mixture is stirred, under cooling, for 15 minutes and then for an additional 20 minutes at room temperature, after which time it is quenched with a large volume of water and allowed to stand at room temperature for about 3 hours. The resultant precipitated solids are then filtered and washed successively with water and petroleum ether. The solvent is then removed under vacuum to yield 1-(m-trifluoromethylphenyl)pyrazole-4-carboxylic acid, m.p. 145°-148° C. (Yield: 89%).

Quelle