Hydrochloric Acid → 2-(4-Aminophenyl)-5-methyl-2,4-dihydro-3H-pyrazol-3-one dihydrochloride

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Reaction Steps

Into 310 ml of methanol, 500 mg of 3-methyl-1-(4-nitrophenyl)-2-pyrazolin-5-one was dissolved, 50 mg of 5% Pd/C and 0.6 ml of conc. hydrochloric acid were added to the solution, and the mixture was stirred under hydrogen atmosphere to consume the calculated amount of hydrogen. Then, the catalyst was filtered off and the filtrate was concentrated. The residue was recrystallized from methanol-ethyl ether to give 409 mg of 1-(4-aminophenyl)-3-methyl-2-pyrazolin-5-one dihydrochloride (Compound No. 50) as pale brown crystals.

Provenance & Evidence