反应详情

126.3 g of 5-hydroxy-1-(2-nitrophenyl)-1H-pyrazole-4-carboxylic acid, ethyl ester is dissolved in 1.6 liter methanol and 1.2 g Pd/C (10%) are added and hydrogenation is performed until H2 -uptake is finished (12 hours). After filtration the solvent is distilled off and the crystalline residue is recrystallized from dimethylformamide/ethanol to yield 78 g of 1-(2-aminophenyl)-5-hydroxy-1H-pyrazole-4-carboxylic acid, ethyl ester as white powder having a melting point of 151°-154° C.

1. custom(12 hours)
2. filtrationAfter filtration the solvent
3. distillationis distilled off
4. customthe crystalline residue is recrystallized from dimethylformamide/ethanol