Sulfuric Acid → 5-amino-1-cyclopentyl-3-ethyl-1H-pyrazole-4-carboxamide

Participants

Reaction Steps

To concentrated sulfuric acid (50 ml) cooled in an ice/sodium chloride bath was added in small portions 1-cyclopentyl-3-ethyl-4-cyano-5-amino-1H-pyrazole. The reaction mixture was warmed to room temperature and stirred for 24 hours. The reaction mixture was slowly added to a solution of concentrated ammonium hydroxide (150 ml) in ice-water (500 ml). A yellow precipitate formed which was collected by filtration, washed with water and dried at 90° C. for 60 hours in high vacuum to afford 3.47 g (85%) of 1-cyclopentyl-3-ethyl-5-amino-1H-pyrazole-4-carboxamide, m.p. 167°-168° C.

Provenance & Evidence