HCID 178499180, compound → HCID 178499176, compound

Participants

Reaction Conditions

Reaction Steps

A 20 L reaction vessel equipped with a digital thermometer and stirrer was charged with palladium on carbon (10% wet paste, 0.170 Kg, 0.14 wt) under nitrogen. In a separate vessel, a slurry of 4-nitro-1H-pyrazole-3-carboxylic acid methyl ester (1.210 Kg, 7.07 mol, 1 wt) in ethanol (12.10 L, 10 vol) was warmed to 30 to 35° C. to effect dissolution and the solution added to the catalyst under nitrogen. Following a nitrogen-hydrogen purge sequence an atmosphere of hydrogen was introduced and the reaction mixture maintained at 28 to 30° C. until reaction completion (5 to 10 hours) was noted by 1H NMR analysis (d6-DMSO). Following a purge cycle, the reaction mixture under nitrogen was filtered and the liquors concentrated under reduced pressure to give 4-amino-1H-pyrazole-3-carboxylic acid methyl ester (0.987 Kg, 98.9% th).

Provenance & Evidence