反应详情

Methyl 4-amino-3,5-dichlorobenzoate (32 g.) dissolved in 48% hydrobromic acid (100 ml.) was cooled to 0° and sodium nitrite (10.5 g.) was added. The solution was added slowly to a mixture of 48% hydrobromic acid (80 ml.) and cuprous bromide (35 g.) and the mixture heated at reflux for 2 hours. After cooling, the mixture was extracted with ethyl acetate and the organic extracts washed with brine, dried (anhydrous magnesium sulphate) and evaporated to give a dark solid. Crystallisation from ethyl acetate gave methyl 4-bromo-3,5-dichlorobenzoate (20 g.). Nuclear Magnetic Resonance Spectrum (NMR) was as follows: 1H: 4.0,3H,s; 7.9,2H,s.

1. temperaturewas cooled to 0°
2. temperaturethe mixture heated
3. temperatureat reflux for 2 hours
4. temperatureAfter cooling
5. extractionthe mixture was extracted with ethyl acetate
6. washthe organic extracts washed with brine
7. dry with materialdried (anhydrous magnesium sulphate)
8. customevaporated
9. customto give a dark solid
10. customCrystallisation from ethyl acetate