反应详情

10.5 ml (203.0 mmol) of bromine are added dropwise at 0° C. to 23.9 g (184.5 mmol) of 3-chloro-2-hydroxypyridine in 240 ml of dimethylformamide, and the mixture is stirred at room temperature for 2 hours. 200 ml of water are subsequently added, and 30 g of sodium sulfite in 100 ml of water are added dropwise. After 15 minutes, the mixture is extracted three times with 200 ml of dichloromethane in each case, the combined organic phases are dried over sodium sulfate and filtered, and the filtrate is evaporated to dryness, giving 36.58 g of 5-bromo-3-chloro-2-hydroxypyridine. ##STR13## m.p.: 168° C. (decomp.)

1. waitAfter 15 minutes
2. extractionthe mixture is extracted three times with 200 ml of dichloromethane in each case
3. dry with materialthe combined organic phases are dried over sodium sulfate
4. filtrationfiltered
5. customthe filtrate is evaporated to dryness