Hydrochloric Acid → 1-(4-Chlorophenyl)-1H-pyrazol-5-amine

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Reaction Steps

21.5 g (0.12 mol) of 4-chlorophenylhydrazine hydrochloride was suspended in 150 mL of methanol, 5 mL of concentrated hydrochloric acid was added, and the mixture was heated at reflux, which gave a clear, yellow-brown solution. To this solution was added dropwise 11.5 g (0.12 mol) of dimethylaminoacrylonitrile over a period of 30 minutes. After 1.5 h at reflux, most of the solvent was removed under vacuum. The remaining residue was taken up in 40 mL of dimethylformamide, and 9 mL of concentrated ammonia solution was added at room temperature. The resulting white precipitate was filtered off and discarded. The clear filtrate was used in Step 10.2 without further purification.

Provenance & Evidence