Stannous Chloride → (3-Fluoro-2-methylphenyl)hydrazine

Temperature

0 °C

24 g 3-Fluoro-2-methyl-aniline was added to 120 ml 25% hydrochloric acid and the mixture cooled to 0° C. A solution of 15 g sodium nitrite in 80 ml water was added dropwise to the resulting suspension at such a rate that the temperature did not rise above 8° C. When the addition was complete, the mixture was stirred 1 h at 0° C. Whilst maintaining the mixture at 0° C., a suspension of 195 g tin (II) chloride in 230 ml 25% aqueous hydrochloric acid was added over 30 min. The mixture was stirred a further 20 min, and the precipitate that formed was filtered. The crude hydrochloride salt was partitioned between water and dichloromethane, and the pH raised to pH8 by the addition of sodium hydroxide solution followed by saturated sodium bicarbonate solution. The phases were separated, the aqueous phase extracted twice with dichloromethane and the combined organic phases dried over sodium sulfate and evaporated. The resulting solid residue was recrystallised from hexane to afford the title compound as a light brown solid (9.2 g, 34% yield, mp 69° C.; EI-MS m/e: 140.1 (M+)).

1. customdid not rise above 8° C
2. additionWhen the addition
3. temperatureWhilst maintaining the mixture at 0° C.
4. additionwas added over 30 min
5. stirringThe mixture was stirred a further 20 min
6. customthe precipitate that formed
7. filtrationwas filtered
8. customThe crude hydrochloride salt was partitioned between water and dichloromethane
9. temperaturethe pH raised to pH8 by the addition of sodium hydroxide solution
10. customThe phases were separated
11. extractionthe aqueous phase extracted twice with dichloromethane
12. dry with materialthe combined organic phases dried over sodium sulfate
13. customevaporated
14. customThe resulting solid residue was recrystallised from hexane

ORD record

ord-d963d7e7f285400cb6bdbf4aad248f97

Source dataset

uspto-grants-2005_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06844345B2