反应详情

Butyllithium (2.5M in hexane; 180 ml) was added dropwise with stirring to a cooled solution of 4-chloro-3-fluorobenzoic acid (37.5 g) in tetrahydrofuran at -40° C. for 3 hours. A solution of dimethyldisulphide (60.5 g) in tetrahydrofuran was added and the mixture was stirred 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 solution (2M). The aqueous layer was acidified to pill and extracted with ether, washed with water, dried (sodium sulphate) and filtered. The flitrate 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 8) as a yellow solid m.p. 149.5°-150.5° C.

1. customthe layers were separated
2. extractionThe aqueous layer was extracted with ether
3. extractionthe combined organic layers were extracted with aqueous sodium hydroxide solution (2M)
4. extractionextracted with ether
5. washwashed with water
6. dry with materialdried (sodium sulphate)
7. filtrationfiltered
8. customThe flitrate was evaporated to dryness
9. customthe residue was triturated with n-hexane
10. filtrationfiltered