Stannous Chloride → (3,4-difluorophenyl)hydrazine

Temperature

10 °C

A stirred mixture of 3,4-difluoroaniline (12.9 g, 0.1 mol) in concentrated hydrochloric acid (60 mL) was chilled to 10° C. with an ice/methanol bath. A solution of sodium nitrite (6.9 g, 0.1 mol) in water (30 mL) was added at a rate which maintained the temperature of the reaction mixture below 10° C. After stirring for 2 hours, the reaction mixture was cooled to 0° C. and a solution of tin(II) chloride. (56.88 g, 0.3 mol) in concentrated hydrochloric acid (50 mL) was added dropwise with vigorous stirring. Additional concentrated hydrochloric acid (150 mL) was added to the reaction mixture and stirring was continued for 2 hours. The reaction mixture was filtered to collect the precipitated hydrochloride salt of the title compound. This precipitate was dissolved in water (75 mL) and the resulting solution was basified with 50% aqueous sodium hydroxide and extracted with ethyl acetate. The organic extracts were dried (Na2SO4) and filtered. The filtrate was concentrated in vacuo to provide the title intermediate as a brown oil (8.11 g, 57.4%).

1. temperaturemaintained the temperature of the reaction mixture below 10° C
2. temperaturethe reaction mixture was cooled to 0° C.
3. stirringstirring
4. waitwas continued for 2 hours
5. filtrationThe reaction mixture was filtered
6. customto collect the precipitated hydrochloride salt of the title compound
7. dissolutionThis precipitate was dissolved in water (75 mL)
8. extractionextracted with ethyl acetate
9. dry with materialThe organic extracts were dried (Na2SO4)
10. filtrationfiltered
11. concentrationThe filtrate was concentrated in vacuo

ORD record

ord-4b6061e83df44b2bb55ff9734dda8405

Source dataset

uspto-grants-2006_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07001895B2