Sulfuric Acid → 4,5-Diamino-1-(2-hydroxyethyl)pyrazole sulfate

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Reaction Steps

A solution of 5-amino-1-(2-hydroxyethyl)-4-nitrosopyrazole (97 g) in a mixed solvent of sulfuric acid (34 ml) and water (2000 ml) was treated with 10% palladium on carbon (10 g) under a hydrogen atmosphere at room temperature for 4 days. After the catalyst was filtered off, the filtrate was concentrated in vacuo. The residue was triturated with methanol and dried in vacuo to give 4,5-diamino-1-(2-hydroxyethyl)pyrazole sulfuric acid salt (90.2 g) as a solid.

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