Reaction #2186223

Reaction equation

sodium hydroxide

5-amino-1 -(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulfinyl-1 H-pyrazole-3-carbonitrile

sulfuric acid

→

title compound

Yield 77.0%

5-Amino-1-(2,6-dichloro-4-trifluoromethylphenyl)-1H-pyrazole-3-carboxylic acid

Yield 77.0%

Conditions

Workup

1. 1
   Extractionextracted with ethyl acetate
2. 2
   DryingThe organic phase was dried over magnesium sulfate
3. 3
   Otherevaporated to dryness
4. 4
   Otherpurified by flash chomatography (silica, chloroform/ethanol) with subsequently trituration with tetrachloromethane

Procedure

A stirred mixture of 5-amino-1 -(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulfinyl-1 H-pyrazole-3-carbonitrile (5.00 g, 11.4 mmol) and sulfuric acid (50%, 100 ml) was heated to 135° C. for 3 hours. The cooled mixture was added to ice water and the pH adjusted to 4 by the addition of aqueous sodium hydroxide (6 N, approx. 230 ml), and then extracted with ethyl acetate. The organic phase was dried over magnesium sulfate, evaporated to dryness and purified by flash chomatography (silica, chloroform/ethanol) with subsequently trituration with tetrachloromethane to give the title compound (3.00 g, yield 77%) as off-white crystals, mp 213° C., 1H NMR (DMSO-d6): 5.69 (bs, 2H, NH2), 5.76 (s, 1H, pyrazole-H), and 8.20 (s, 2H, Ar—H).

Source