Reaktion #40715

Reaktionsgleichung

POCl3

N,N-dimethylformamide

2-fluorophenylacetic acid

N,N-dimethylformamide

hydrazine hydrate

→

4-(2-fluorophenyl)-1H-pyrazole

Lösungsmittel

ethanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigewere at 0-5° C.
2. 2
   workup.ADDITIONwas added dropwise
3. 3
   SonstigeThe mixture was subsequently quenched with ice-water
4. 4
   workup.ADDITIONby adding NaOH
5. 5
   FiltrationThe resulting solid was filtered off
6. 6
   Extraktionthe solution was extracted with dichloromethane
7. 7
   Sonstigethe organic phase was dried
8. 8
   Einengenconcentrated
9. 9
   SonstigeThe oil obtained in this way
10. 10
    Temperaturthe reaction mixture was heated at 55° C. for 3 hours
11. 11
    Sonstigethe solvent was evaporated
12. 12
    Sonstigedried

Vorschrift

11.08 ml of N,N-dimethylformamide was slowly added dropwise to 11.03 ml of POCl3 were at 0-5° C. while stirring and, after about 5 minutes a solution of 2-fluorophenylacetic acid (6 g, 38.9 mmol) in 20 ml of N,N-dimethylformamide was added dropwise. The mixture was then heated at 70° C. for about 17 hours. The mixture was subsequently quenched with ice-water and the mixture was made alkaline by adding NaOH. The resulting solid was filtered off, the solution was extracted with dichloromethane, and the organic phase was dried and concentrated. The oil obtained in this way was directly dissolved in 50 ml of ethanol. 7.3 ml of hydrazine hydrate were added, and the reaction mixture was heated at 55° C. for 3 hours. After the reaction was complete, the solvent was evaporated and the remaining solid was stirred with water and then dried. 2.65 g of 4-(2-fluorophenyl)-1H-pyrazole were obtained.

Quelle