反应详情

温度

-5 °C

An aqueous solution of sodium nitrite (3.64 g, dissolved in 4 mL of water, 52 mmol) was added drop wise to the concentrated hydrochloric acid (15 mL), cooled to −10° C. to −5° C. 3-Amino-4-bromo-2,6-dichloro-benzoic acid (5 g, 17 mmol, Step c) was added to the above solution portion-wise while maintaining the temperature at about −5° C. The reaction mixture was stirred at the same temperature for about 2 hours. Hypophosphorous acid (9 mL, 170 mmol) was added very slowly over a period of 1 hour at the same temperature. The reaction mixture was stirred at the same temperature for about 3 hours and kept in refrigerator overnight. A precipitate was observed at this stage. The reaction mixture was allowed to warm to room temperature and kept for another 2 hours at the same temperature. The reaction mixture was filtered, the residue was washed with cold water and dried to yield 4-bromo-2,6-dichloro-benzoic acid as a yellowish solid (2 g, 42%).

1. temperaturecooled to −10° C. to −5° C
2. stirringThe reaction mixture was stirred at the same temperature for about 3 hours
3. customkept in refrigerator overnight
4. temperatureto warm to room temperature
5. waitkept for another 2 hours at the same temperature
6. filtrationThe reaction mixture was filtered
7. washthe residue was washed with cold water
8. customdried