Acetic Acid → 4-Nitroindazole

Participants

Reaction Conditions

Reaction Steps

Alternatively, to a 4-necked 5-L jacketed round bottom flask fitted with a mechanical stirrer and a thermocouple was charged the nitroaniline (100 g, 1.0 equiv.) and acetic acid (2000 mL). The solution was cooled to 14° C. A chilled to about 1° C. (ice-water bath) solution of sodium nitrite (100 g, 2.2 equiv.) in water (250 mL) was added quickly in one portion. The internal temperature rose from 14° C. to 27.6° C. over 5 min., stayed at this temperature for 5 min. before gradually cooling to 15° C. The mixture was stirred for 24 h after which it was concentrated in vacuo to an approximate volume of 500 mL. The residue was re-slurried in water (1800 mL) at ambient temperature for 21 hours. The orange solid was filtered, washed with water (3×250 mL), and dried in a vacuum oven at 70° C. to afford 97.0 g of the title compound as a bright orange solid.

Provenance & Evidence