Sulfuric Acid → 5-Amino-1-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)pyrazole
Reaction equation
[NH2:1][C:2]1[N:6]([C:7]2[C:12]([F:13])=[C:11]([F:14])[C:10]([C:15]([F:18])([F:17])[F:16])=[C:9]([F:19])[C:8]=2[F:20])[N:5]=[CH:4][C:3]=1C(OCC)=O.S(=O)(=O)(O)O>>[NH2:1][C:2]1[N:6]([C:7]2[C:12]([F:13])=[C:11]([F:14])[C:10]([C:15]([F:18])([F:17])[F:16])=[C:9]([F:19])[C:8]=2[F:20])[N:5]=[CH:4][CH:3]=1Participants
3
Conditions
- Temperature
- 120 °C
Procedure
100 g (0.270 mol) of 5-amino-4-ethoxycarbonyl-1-(2,3,5,6-tetrafluoro-4-trifluoromethyl-phenyl)-pyrazole are suspended in 250 ml of 50 percent strength aqueous sulphuric acid and the suspension is warmed to 120° C. in the course of 2 hours; the more highly volatile constituents are thereby distilled off over a bridge. The mixture is kept at 115° C.-120° C. for a further 3 hours and is cooled and diluted with 400 ml of water, the pH is brought to 2 with dilute aqueous sodium hydroxide solution and the precipitate formed is filtered off with suction. It is washed neutral with water and dried in vacuo. 77.3 g (96% of theory) of 5-amino-1-(2,3,5,6-tetrafluoro-4-trifluoromethyl-phenyl)-pyrazole of melting point 103° C.-104° C. are obtained.