反应详情

温度

-40 °C

n-Butylithium (2.5M in hexane, 180 ml) was added dropwise to a stirred, cooled solution of 4-chloro-3-fluorobenzoic acid (37.5 g) in tetrahydrofuran while maintaining the temperature below -40° C. The mixture was stirred at -40° C. for 3 hours. Dimethyl disulphide (60.5 g) in tetrahydrofuran was added dropwise and the mixture was stirred at -40° C. for half an hour and at room temperature overnight. Hydrochloric acid (2M) was added and the layers were separated. The aqueous layer was extracted with ether and the combined organic layers were extracted with aqueous sodium hydroxide (2M). The aqueous extract was acidified to pH1 and extracted with ether. washed with water, dried (Na2SO4) and filtered. The filtrate was evaporated to dryness and the residue was triturated with n-hexane and filtered to give 4-chloro-3-fluoro-2-(methylsulphenyl)benzoic acid (32.84 g) as a white solid m.p. 149.5°-150.50° C.

1. temperaturewhile maintaining the temperature below -40° C
2. stirringthe mixture was stirred at -40° C. for half an hour and at room temperature overnight
3. customthe layers were separated
4. extractionThe aqueous layer was extracted with ether
5. extractionthe combined organic layers were extracted with aqueous sodium hydroxide (2M)
6. extractionThe aqueous extract
7. extractionextracted with ether
8. washwashed with water
9. dry with materialdried (Na2SO4)
10. filtrationfiltered
11. customThe filtrate was evaporated to dryness
12. customthe residue was triturated with n-hexane
13. filtrationfiltered