反应详情

To a stirring solution of diisopropyl ethyl amine (11.1 ml, 81.08 mmol) in THF (50 ml) was added dropwise a solution of BuLi (1.46 M, 43.3 ml, 73.65 mmol) in hexane below −65° C. and the mixture was stirred for 40 minutes. To this solution was added dropwise 2,4-dichloropyridine (10 g, 67.57 mmol) in THF (15 mL) at −78° C. and stirred for 30 minutes. Carbon dioxide generated from freshly crushed dry ice was passed through CaCl2 guard tube and then charged into the reaction mixture for 10 minutes and the reaction mixture was slowly allowed to come to room temperature. The solvent was evaporated under reduced pressure and dissolved in a minimum volume of water. The aqueous layer was washed with water and acidified to pH 4 with conc. HCl. It was then extracted with ethyl acetate, the organic layer was washed with brine and dried over sodium sulfate. The organic solvent was removed under reduced pressure to provide 2,4-dichloronicotinic acid (10.6 g, 82%) as off white solid.

1. stirringstirred for 30 minutes
2. customwas passed through CaCl2 guard tube
3. additioncharged into the reaction mixture for 10 minutes
4. customto come to room temperature
5. customThe solvent was evaporated under reduced pressure
6. dissolutiondissolved in a minimum volume of water
7. washThe aqueous layer was washed with water
8. extractionIt was then extracted with ethyl acetate
9. washthe organic layer was washed with brine
10. dry with materialdried over sodium sulfate
11. customThe organic solvent was removed under reduced pressure