Hydrochloric Acid → Pyrazole-1-carboxamidine monohydrochloride

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Reaction Steps

In a 500 ml four-necked flask fitted with gas inlet tube and gas outlet tube, internal thermometer and reflux condenser with in each case two safety wash bottles connected upstream and downstream, 34.1 g (0.5 mol.) of pyrazole and 21.0 g (0.5 mol.) of cyanamide are dissolved in 330 ml of dimethoxyethane. At 80° C., dry hydrogen chloride gas is introduced into the reaction solution at a rate of about 15 l/h for about 50 minutes. The solution is then allowed to cool and the precipitated solid is removed by filtration. The product obtained is dried under reduced pressure (100 mbar, 80° C.) to give 1H-pyrazole-1-carboxamidine hydrochloride in the form of a colorless, finely crystalline solid. Yield: 70.6 g (96%), melting point: 160 to 168° C. (literature: 165 to 166° C.) 13C-NMR (DMSO-d6) δ 152.3, 146.0, 131.5, 111.9.

Provenance & Evidence