反应详情

In the course of from 30 to 45 minutes, at 20°, with stirring, 43.9 g of bromine are added dropwise to a solution of 45.9 g of 2-hydroxy-5-methoxy-benzoic acid methyl ester in 125 ml of heptane. The reaction mixture is then stirred for a further 3 to 4 hours, then diluted with 110 ml of water and stirred for a further one hour and then 295 ml of heptane and 46 ml of tert-butyl methyl ether are added thereto. The mixture is then heated to from 50° to 55° and the aqueous phase is separated off. The organic phase is extracted twice with 114 ml of water each time and cooled to -20°. The crystals which precipitate are filtered off and dried under a high vacuum. 3-Bromo-2-hydroxy-5-methoxy-benzoic acid methyl ester is thus obtained; yield 82.5% of the theoretical yield.

1. stirringThe reaction mixture is then stirred for a further 3 to 4 hours
2. stirringstirred for a further one hour
3. temperatureThe mixture is then heated to from 50° to 55°
4. customthe aqueous phase is separated off
5. extractionThe organic phase is extracted twice with 114 ml of water each time
6. temperaturecooled to -20°
7. filtrationThe crystals which precipitate are filtered off
8. customdried under a high vacuum