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0 °C

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:

1. filtrationThe solution was clarified by filtration on a sinter funnel
2. customevaporated to dryness under reduced pressure
3. customThe brown solid obtained
4. customThe white precipitate obtained
5. filtrationwas filtered off on a sinter funnel
6. customdried under vacuum at room temperature