Sulfuric Acid → 5-Amino-1-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)pyrazole

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence