反应详情

温度

-20 °C

2-Amino-3,5-dichloro-6-methylpyridine (3.54 g, 20 mmol) was suspended in aqueous 48% HBr solution at room temperature and the mixture was cooled to −20° C. This suspension was maintained at −20° C. while bromine (2.87 mL, 56 mmol) was added dropwise. The resultant paste was stirred for 30 minutes at this temperature before the dropwise addition of a cooled solution of sodium nitrite (3.59 g, 52 mmol) in water (5 mL). At this point the reaction mixture was allowed to warm to room temperature. After stirring for a further 60 minutes, the mixture was again cooled to −20° C. and treated with a solution of sodium hydroxide (16 g, 0.4 mol) in water (20 mL). This mixture was extracted with ethyl acetate and the organic layer washed with water and then brine solution. The organic solution was dried over MgSO4, filtered and the residue obtained from solvent evaporation was purified using silica gel chromatography [eluent: 10% ethyl acetate in hexane]. 2-Bromo-3,5-dichloro-6-methylpyridine 1-4 (2.14 g, 45%) was obtained as a solid.

1. additionwas added dropwise
2. temperatureto warm to room temperature
3. temperaturethe mixture was again cooled to −20° C.
4. extractionThis mixture was extracted with ethyl acetate
5. washthe organic layer washed with water
6. dry with materialThe organic solution was dried over MgSO4
7. filtrationfiltered
8. customthe residue obtained from solvent evaporation
9. customwas purified