Hydrochloric Acid → 1-[4-(aminosulfonyl)phenyl]-5-(4-chlorophenyl)-1H-pyrazole-3-carboxylic acid

Participants

Reaction Steps

Methyl 1-(4-aminosulfonylphenyl)-5-(4-chlorophenyl)-1H-pyrazole-3-carboxylate from Step 2 (1.0 g, 2.66 mmol) was added to tetrahydrofuran (20 mL). Aqueous sodium hydroxide (2.5 N, 2.7 mL) and water (2.5 mL) were added, and the suspension was heated to reflux and held for 16 hours. The solids dissolved during this time. The reaction was cooled to room temperature, and hydrochloric acid solution (1 N, 11 mL) was added. The aqueous suspension was extracted with methylene chloride (2×20 mL). The combined organic solution was dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo to an oil. Trituration with 30 mL of dichloromethane yielded, upon filtration and drying, 1-(4-aminosulfonylphenyl)-5-(4-chlorophenyl)-1H-pyrazole-3-carboxylic acid (0.90 g (94%)) as a white solid: mp 126-128° C.

Provenance & Evidence