反应详情

To concentrated HBr (48%, 28.6 mL) was added 5-methyl-3-nitro-pyridin-2-ylamine (5 g, 32.6 mmol) in portions at 0° C. temperature with stirring. The mixture was stirred until the internal temperature reached to −10° C., then bromine was added drop wise. A solution of NaNO2 (7.6 g, 110.84 mmol) in water (11 mL) was added slowly to maintain the reaction mixture temperature below 0° C. The dark mixture (gas evolution was observed) was stirred for 1 h at 0° C. then was carefully treated (slow addition) with a solution of NaOH (12 g, 300 mmol) in water (17 mL) while maintaining the internal temperature below 20° C. The mixture was stirred for an additional 1 h, then was filtered, dried under vacuum for 6 h and purified by recrystalization using 95% EtOH to get pure 2-bromo-5-methyl-3-nitro-pyridine (1.96 g) as yellow solid in 28% first crop yield. ESMS m/z (relative intensity): 217 (M+H)+ (100).

1. stirringThe mixture was stirred until the internal temperature
2. customreached to −10° C.
3. temperatureto maintain the reaction mixture temperature below 0° C
4. stirringThe dark mixture (gas evolution was observed) was stirred for 1 h at 0° C.
5. additionthen was carefully treated
6. temperaturewhile maintaining the internal temperature below 20° C
7. stirringThe mixture was stirred for an additional 1 h
8. filtrationwas filtered
9. customdried under vacuum for 6 h
10. custompurified by recrystalization