反应详情

A solution of bromine (1.6 g) in dry carbon disulphide (10 cm3) was added over 5 minutes to a solution of 2,6-difluorophenol (1.3 g) in dry carbon disulphide (10 cm3). To the stirred reaction mixture was added 5 drops of 48% hydrogen bromide solution. The mixture was heated for 2 hours at the reflux temperature, then allowed to stand at the ambient temperature (ca 22° C.) for 16 hours. After a further period of heating (4 hours) the mixture was allowed to stand for 24 hours before being poured onto water (20 cm3). To the mixture was added saturated sodium metabisulphite solution (30 cm3). The layers were separated, and the organic phase was washed with saturated sodium hydrogen carbonate solution (20 cm3) and water (20 cm3). The organic layer was dried over anhydrous sodium sulphate then evaporated under reduced pressure to given an oil which solidified. The crude product was distilled in a Kugelrohr apparatus at an oven temperature of 100° C. under reduced pressure (ca. 20 mmHg). The distillate crystallised to give 4-bromo-2,6-difluorophenol as a white solid (0.48 g).

1. customTo the stirred reaction mixture
2. temperatureThe mixture was heated for 2 hours at the reflux temperature
3. temperatureAfter a further period of heating (4 hours) the mixture
4. waitto stand for 24 hours
5. additionbefore being poured onto water (20 cm3)
6. customThe layers were separated
7. washthe organic phase was washed with saturated sodium hydrogen carbonate solution (20 cm3) and water (20 cm3)
8. dry with materialThe organic layer was dried over anhydrous sodium sulphate
9. customthen evaporated under reduced pressure
10. distillationThe crude product was distilled in a Kugelrohr apparatus at an oven temperature of 100° C. under reduced pressure (ca. 20 mmHg)
11. customThe distillate crystallised