Hydrogen Bromide → 5-Bromo-2-methylphenol

To a solution of 5-amino-2-methylphenol (10 g, 81.2 mmol) in hydrobromic acid (40 mL, 48% solution) and water (50 mL) at 0° C. was added a solution of sodium nitrite (5.6 g, 81.2 mmol) in water (15 mL) and the mixture stirred at this temperature for 30 minutes. To this was added copper (I) bromide (11.6 g, 81.2 mmol) in hydrobromic acid (15 mL, 48% solution) and the reaction was subsequently heated at reflux for 2 hours. Upon cooling to room temperature the resulting mixture was extracted with ethyl acetate (2×200 mL) and the combined organic extracts were washed with aqueous potassium hydroxide solution (˜1 M, 200 mL), dried (magnesium sulphate) and concentrated under reduced pressure. The crude product was purified by column chromatography [SiO2; light petroleum to 4:1 light petroleum-ethyl acetate] to give the title compound as a colourless oil, which crystallised to give fine colourless needles upon standing overnight (4 g, 26%). Rf=0.26 [4:1 light petroleum-ethyl acetate]. 1H NMR δ 2.21 (3 H, s), 4.89-4.95 (1 H, br, s), 6.96-6.97 (1 H, br, m), 6.99-7.00 (2 H, m).

1. temperaturethe reaction was subsequently heated
2. temperatureat reflux for 2 hours
3. extractionwas extracted with ethyl acetate (2×200 mL)
4. washthe combined organic extracts were washed with aqueous potassium hydroxide solution (˜1 M, 200 mL)
5. dry with materialdried (magnesium sulphate)
6. concentrationconcentrated under reduced pressure
7. customThe crude product was purified by column chromatography [SiO2; light petroleum to 4:1 light petroleum-ethyl acetate]

ORD record

ord-5e54a98d82144ffc983c6b0be72907d7

Source dataset

uspto-grants-2008_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07407649B2