反应详情

A mixture of 2-amino-4,6-dimethylpyridine (90 g, 0.736 mol) and sodium chloride (216 g, 3.69 mol) in concentrated hydrochloric acid (720 mL) was cooled to between −15 and −20° C. A solution of sodium nitrite (71.2 g, 1.03 mol) in water (135 mL) was added over 30 min. More sodium chloride (216 g, 3.69 mol) was added and the reaction mixture was allowed to warm to ambient temperature and stirred for 1 h. The reaction mixture was basified with solid bicarbonate (700 g) and extracted with dichloromethane (1 L), filtered and the two phases separated. The organic layer was concentrated in vacuo and the crude purified by flash column chromatography over silica gel (100-200 mesh) with 20% dichloromethane in petroleum ether as eluent to afford 2-chloro-4,6-dimethylpyridine (40 g, 38%) as a solid.

1. temperaturewas cooled to between −15 and −20° C
2. extractionextracted with dichloromethane (1 L)
3. filtrationfiltered
4. customthe two phases separated
5. concentrationThe organic layer was concentrated in vacuo
6. customthe crude purified by flash column chromatography over silica gel (100-200 mesh) with 20% dichloromethane in petroleum ether as eluent