Sulfuric Acid → 4-Bromo-2-fluorobenzaldehyde

Participants

Reaction Steps

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.

Provenance & Evidence