Hydrochloric Acid → 5-amino-4-aminomethyl-1-(2-hydroxyethyl)-1H-pyrazole dihydrochloride

Under a nitrogen atmosphere, 10% palladium on active carbon (125 g) and methanol (3.75 L) were placed in a 5.0 L of three-necked flask. To the mixture was added 5-amino-4-cyano-1-(2-hydroxyethyl)-1H-pyrazole (250 g). The mixture was stirred at room temperature for 1 hour under a hydrogen atmosphere. To the reaction mixture was added 4N hydrogen chloride solution in methanol (1.65 L), and the mixture was stirred at room temperature for 1.5 hours under a hydrogen atmosphere. To the reaction mixture was added water (1.2 L). The catalyst was filtered off and washed with 50% aqueous methanol, and the filtrate was evaporated in vacuo. The residue was triturated with isopropanol/ethyl acetate (1:1). The precipitate was collected by filtration on a glass filter, washed with ethyl acetate and dried in vacuo to give 5-amino-4-aminomethyl-1-(2-hydroxyethyl)-1H-pyrazole dihydrochloride (358 g) as a white solid.