Sulfuric Acid → 4-Bromo-2-fluorobenzaldehyde

To a stirred mixture of glacial acetic acid (88 ml.), acetic anhydride (90 g.) and 4-bromo-2-fluorotoluene (10 g.) at -10° was added concentrated sulphuric acid (12 ml.) over 20 minutes, keeping the temperature around 0°. Solid chromium trioxide (14.7 g.) was added over 40 minutes keeping the temperature below 5°. The mixture was stirred for 15 minutes. The mixture was poured onto ice (300 g.) and stirred. The mixture was extracted with ether (2×300 ml.). The organic extracts were washed with 2% sodium carbonate solution (2×100 ml.). After evaporation the crude diacetate was treated with a mixture of water (30 ml.), ethanol (30 ml.) and conc sulphuric acid (3 ml.) and the mixture refluxed for 1 hour. After cooling the product was extracted into ether, dried and evaporated. Recrystallisation from hexane yielded the title product. Nuclear magnetic resonance (NMR) was as follows. 7.6, 3H, M; 10.0, 1H, s.

1. customthe temperature around 0°
2. customthe temperature below 5°
3. additionThe mixture was poured onto ice (300 g.)
4. stirringstirred
5. extractionThe mixture was extracted with ether (2×300 ml.)
6. washThe organic extracts were washed with 2% sodium carbonate solution (2×100 ml.)
7. customAfter evaporation the crude diacetate
8. additionwas treated with a mixture of water (30 ml.), ethanol (30 ml.) and conc sulphuric acid (3 ml.)
9. temperaturethe mixture refluxed for 1 hour
10. temperatureAfter cooling the product
11. extractionwas extracted into ether
12. customdried
13. customevaporated
14. customRecrystallisation from hexane

ORD record

ord-944c01d7acd2437980f2c4253b7f2934

Source dataset

uspto-grants-1996_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05502073