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

Participants

Reaction Conditions

Reaction Steps

A stirred mixture of 18.6 grams (0.500 mole) of ethyl 5-amino-1-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)pyrazole-4-ylcarboxylate, 23 mL of water, and 23 mL of sulfuric acid was heated at 130° C. for six hours. After the reaction mixture was cooled, 75 mL of crushed ice was added. A solid had formed and was collected by filtration; the filtrate was saved. This solid was washed with water and diethyl ether, allowed to dry, and set aside for further purification. To the filtrate was added an aqueous sodium hydroxide solution until a pH of 9.0 was obtained. A solid formed and was collected by filtration. This solid was washed with water and dried to yield 3.8 grams of 5-amino-1-(2,3,5,6-tetrafluoro-4-trifluoromethylphenyl)pyrazole, m.p. 102.5°-104.5° C. The nmr spectrum was consistent with the proposed structure.

Provenance & Evidence