Hydrogen Peroxide → 5-Bromo-2,4-dimethylphenol

Temperature

-70 °C

In a glovebox, 1,5-dibromo-2,4-dimethylbenzene (10.000 g, 37.9 mmol) is dissolved in dry THF (140 mL) in a one-neck round bottomed flask with a thermometer well. The flask is capped with a septum, and removed from the glovebox. Nitrogen purge is provided via a needle through the septum, and the solution is cooled to −70° C. using a dry ice/acetone bath. Butyllithium (BuLi) (1.6M in hexanes, 26 mL, 42 mmol) is added slowly, maintaining the temperature below −65° C. After stirring for 80 minutes at −70° C., trimethylborate (B(OMe)3) (4.2 mL, 37.9 mmol) is added slowly, maintaining the temperature below −62° C., and then the reaction is allowed to slowly warm to room temperature overnight. Solvents are removed on a rotovap, leaving a very pale yellow oily solid, which is dissolved in tetrahydrofuran (THF) (100 mL) and treated with hydrogen peroxide (H2O2) (30% aq, 13 mL) and sodium hydroxide (NaOH) (1M, 25 mL) for two hours. The reaction is then quenched with ammonium chloride (NH4Cl) (aq) and extracted into ether (2×100 mL). The organic fractions are combined, dried over sodium sulfate, filtered and dried in vacuo. Yield=6.60 g (86.7%) of pale yellow waxy solid.

1. customThe flask is capped with a septum
2. customremoved from the glovebox
3. customNitrogen purge
4. customis provided via a needle through the septum
5. temperaturemaintaining the temperature below −65° C
6. temperaturemaintaining the temperature below −62° C.
7. temperatureto slowly warm to room temperature overnight
8. customSolvents are removed on a rotovap
9. customleaving a very pale yellow oily solid, which
10. customThe reaction is then quenched with ammonium chloride (NH4Cl) (aq)
11. extractionextracted into ether (2×100 mL)
12. dry with materialdried over sodium sulfate
13. filtrationfiltered
14. customdried in vacuo

ORD record

ord-344c162ce35341f1a59f59845eb7adf0

Source dataset

uspto-grants-2013_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08592615B2