2-Amino-4-bromo-5-chlorobenzoic acid → 4-Bromo-5-chloro-2-hydrazinylbenzoic acid hydrochloride

Temperature

0 °C

A solution of sodium nitrite (3.03 g, 43.9 mmol) in water (14.8 mL) was added dropwise to a cooled (−10° C., NaCl-ice bath) suspension of 2-amino-4-bromo-5-chlorobenzoic acid (10.0 g, 39.9 mmol) in 37% aqueous HCl (39.9 mL) and water (13.3 mL), at such rate that the temperature did not exceed 0° C. The resulting suspension was stirred at 0° C. for 15 min, then was treated with a solution of tin(II) chloride hydrate (22.7 g, 120 mmol) in 37% aqueous HCl (17 mL). The resulting mixture was warmed to room temperature and stirred for 60 min. The precipitate was collected by filtration, washed with water and air-dried overnight to give 4-bromo-5-chloro-2-hydrazinylbenzoic acid hydrochloride as an off-white solid (12.86 g, 96% yield). Mass spectrum m/z 365, 267 (M+H)+. 1H NMR (400 MHz, DMSO-d6) δ 9.05 (br. s., 1H), 7.95 (s, 1H), 7.55 (s, 1H).

1. temperaturea cooled
2. customdid not exceed 0° C
3. temperatureThe resulting mixture was warmed to room temperature
4. stirringstirred for 60 min
5. filtrationThe precipitate was collected by filtration
6. washwashed with water
7. customair-dried overnight

ORD record

ord-41e8152100e04d69b9a3bcca691a6788

Source dataset

uspto-grants-2016_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09334290B2