[CH3:1][N:2]1[C:6]([NH:7][NH2:8])=[C:5]([N+:9]([O-])=O)[C:4]([CH3:12])=[N:3]1.[ClH:13].O>C(O)C.[Pd]>[ClH:13].[ClH:13].[NH2:9][C:5]1[C:4]([CH3:12])=[N:3][N:2]([CH3:1])[C:6]=1[NH:7][NH2:8]A suspension of 8.6 g (0.05 mol) of 1,3-dimethyl-5-hydrazino-4-nitropyrazole and 1.5 g of 5% by weight palladium-on-charcoal containing 50% water in 200 cm3 of ethanol was placed in a hydrogenator. After stirring under a hydrogen pressure of 10 bar, at a temperature of 75° C. for 3 hours, the reaction medium was poured into a solution of 60 cm3 of ethanol and 20 cm3 of 12 N hydrochloric acid cooled to 0° C. The solution was clarified by filtration on a sinter funnel and then evaporated to dryness under reduced pressure. The brown solid obtained was taken up, at reflux, in 50 cm3 of 5 N hydrochloric ethanol and 14 cm3 of water and was then cooled to room temperature. The white precipitate obtained was filtered off on a sinter funnel and then dried under vacuum at room temperature. 9.5 g of 4-amino-1,3-dimethyl-5-hydrazinopyrazole dihydrochloride were obtained in the form of white crystals, the melting point of which was from 202 to 204° C. The elemental analysis calculated for C5H11N5.2HCl was:
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