反应详情

温度

0 °C

Mix water (60mL), concentrated sulfuric acid (60mL) and 4-fluoro-2-nitro-6-bromoaniline (9.65g, 41mmol). Cool to 0° C. and add solid sodium nitrite (4.25g, 61mmol) in small portions at such a rate as not to exceed 5° C. Stir for 30 minutes and add ferrous sulfate heptahydrate (5.6g, 20.5mmol) and ethanol (18mL). Stir with warming to room temperature over 2 hours. Add water (200mL), separate the organic phase and wash the aqueous phase with methylene chloride (2×). Combine the organic phases, dry (MgSO4) and evaporate the solvent in vacuo. Purify by silica gel chromatography (5% ethyl acetate/hexane) give 3-bromo-5-fluoronitrobenzene (4.5g); bp 65°-70° C.@1.0mm Hg.

1. customto exceed 5° C
2. stirringStir
3. temperaturewith warming to room temperature over 2 hours
4. customAdd water (200mL), separate the organic phase
5. washwash the aqueous phase with methylene chloride (2×)
6. dry with materialCombine the organic phases, dry (MgSO4)
7. customevaporate the solvent in vacuo
8. customPurify by silica gel chromatography (5% ethyl acetate/hexane)