Hydrogen Bromide → 4-(2-Bromoethyl)-1,2-difluorobenzene

17.59 g (111 mmol) of 2-(3,4-difluorophenyl)ethanol, 16 ml (137 mmol) of hydrogen bromide, 6.8 ml (234 mmol) of conc. sulfuric acid were added in the order, and the mixture was heated under reflux for 3 hrs. The reaction mixture was poured onto an ice-bath, an organic layer and an aqueous layer were separated, the aqueous layer was extracted with ether, the extract combined with the organic layer was washed with a saturated aqueous solution of sodium hydrogen carbonate, and dried over anhydrous magnesium sulfate. The solvent was distilled off, the solution condensed and purified by vacuum distillation to obtain 21.96 g (bp 68-70° C./2-4 Torr.) of oily product. The oily product was purified by column chromatography (elution solvent: hexane:ethyl acetate=3:1), the eluate was further purified by vacuum distillation to obtain 19.79 g of the title compound (81%, bp 73-75° C./4 Torr.) as oily product.

1. temperaturethe mixture was heated
2. temperatureunder reflux for 3 hrs
3. additionThe reaction mixture was poured onto an ice-bath
4. customan organic layer and an aqueous layer were separated
5. extractionthe aqueous layer was extracted with ether
6. washwas washed with a saturated aqueous solution of sodium hydrogen carbonate
7. dry with materialdried over anhydrous magnesium sulfate
8. distillationThe solvent was distilled off
9. customthe solution condensed
10. distillationpurified by vacuum distillation
11. customto obtain 21.96 g (bp 68-70° C./2-4 Torr.) of oily product
12. customThe oily product was purified by column chromatography (elution solvent: hexane:ethyl acetate=3:1)
13. distillationthe eluate was further purified by vacuum distillation

ORD record

ord-ddae51dcc0024154a85edb69abd871f2

Source dataset

uspto-grants-2002_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06500503B2