反应详情

温度

0 °C

A mixture of 2-bromo-4-fluoro-6-nitrophenylamine (55 g, 234 mmol) in 50% sulphuric acid (500 ml) was cooled to 0° C. then treated dropwise with a solution of sodium nitrite (22.6 g, 328 mmol) in water (100 ml) keeping the internal temperature <5° C. Following the addition of the sodium nitrite the reaction was stirred at <5° C. for 1 h. Ethanol (75 ml) was then added followed by ferrous sulfate heptahydrate (32.5 g, 117 mmol) and the reaction stirred at ambient temperature for 2 h. The reaction was diluted with water (1 l) and extracted with dichloromethane (2×500 ml). The organics were combined, washed with saturated aqueous sodium hydrogencarbonate, water and brine, then dried for 1 h over anhydrous magnesium sulfate containing decolorizing charcoal (5 g). Filtration through glass micro-fibre filter paper (Whatman GF/A) and evaporation to dryness gave an oil which on standing furnished 1-bromo-3-fluoro-5-nitrobenzene as colourless crystals (50 g, 97%): δH (360 MHz, CDCl3) 7.61 (1H, ddd, J 8, 2 and 2), 7.90 (1H, ddd, J 8, 2 and 2), 8.20-8.23 (1H, m).

1. customthe internal temperature <5° C
2. stirringthe reaction stirred at ambient temperature for 2 h
3. extractionextracted with dichloromethane (2×500 ml)
4. washwashed with saturated aqueous sodium hydrogencarbonate, water and brine
5. dry with materialdried for 1 h over anhydrous magnesium sulfate containing decolorizing charcoal (5 g)
6. filtrationFiltration
7. customthrough glass micro-fibre filter paper (Whatman GF/A) and evaporation to dryness
8. customgave an oil which