Hydrochloric Acid → 2-Fluoro-4-chloro-5-hydroxyphenylhydrazine hydrochloride

Temperature

0 °C

First, 32.3 g of 5-amino-2-chloro-4-fluorophenol was mixed with 150 ml of concentrated hydrochloric acid, and the mixture was stirred at 50° C. for 30 minutes, to which a solution of 15 g of sodium nitrite dissolved in 40 ml of water was added dropwise at 0° C. over 10 minutes. After stirring at 0° C. for 1 hour, the mixture was cooled to −50° C. Then, a solution of 132 g of tin (11) chloride dissolved in 132 g of concentrated sulfuric acid was rapidly added dropwise at −50° C., and the mixture was gradually warmed to room temperature and stirred for 1 hour. The solids formed were collected by filtration and dried at 80° C. under reduced pressure to give 75 g of the crude 2-fluoro-4-chloro-5-hydroxyphenylhydrazine hydrochloride crystals.

1. additionwas added dropwise at 0° C. over 10 minutes
2. temperaturethe mixture was cooled to −50° C
3. additionwas rapidly added dropwise at −50° C.
4. temperaturethe mixture was gradually warmed to room temperature
5. stirringstirred for 1 hour
6. customThe solids formed
7. filtrationwere collected by filtration
8. customdried at 80° C. under reduced pressure

ORD record

ord-b3d797874be2464c96341c05c5fda4e3

Source dataset

uspto-grants-2005_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06869913B1