Sulfuric Acid → 1-Bromo-4-fluoro-2-methyl-3-nitrobenzene

Temperature

0 °C

A 250 mL single neck flask equipped with magnetic stirrer was charged with 3-fluoro-2-nitrotoluene (4.75 g, 30.6 mmol) and trifluoroacetic acid (20 mL). Sulfuric acid (96%, 10 mL) was added dropwise over 10 minutes at 0° C. followed by N-bromosuccinimide (8.12 g, 45.6 mmol) in portions over 15 min (causing an exotherm of 3° C.). The reaction was stirred at 0° C. for 20 min and then stirred at mom temperature for 3.5 h. After this time, the reaction mixture was poured in to a 1:1 mixture of ice/water (500 mL), diluted with 95:5 hexanes/methylene chloride (250 mL) and the layers were separated. The aqueous layer was extracted with hexanes (100 mL) and the combined organic layers were washed with water (2×100 mL), saturated aqueous sodium bicarbonate (100 mL), brine (100 mL) and dried over sodium sulfate. The drying agent was removed by filtration, and the filtrate was concentrated under reduced pressure. The crude product was suspended in hexanes (40 mL) and heated until dissolved. The solution was evaporated to a volume to 20 mL and allowed to cool to room temperature overnight. The product was filtered and washed with cold hexanes (3×2 mL) to afford (C) (4.29 g, 60%) as a yellow crystalline solid. The filtrate was concentrated to dryness and the residue was dissolved in hot hexanes (5 mL). After cooling to room temperature, stirring for 2 h, and filtering, an additional 1.30 g of C (18%) was isolated.

1. customA 250 mL single neck flask equipped with magnetic stirrer
2. customan exotherm of 3° C.
3. stirringstirred at mom temperature for 3.5 h
4. customthe layers were separated
5. extractionThe aqueous layer was extracted with hexanes (100 mL)
6. washthe combined organic layers were washed with water (2×100 mL), saturated aqueous sodium bicarbonate (100 mL), brine (100 mL)
7. dry with materialdried over sodium sulfate
8. customThe drying agent was removed by filtration
9. concentrationthe filtrate was concentrated under reduced pressure
10. temperatureheated
11. dissolutionuntil dissolved
12. customThe solution was evaporated to a volume to 20 mL
13. temperatureto cool to room temperature overnight
14. filtrationThe product was filtered
15. washwashed with cold hexanes (3×2 mL)

ORD record

ord-0e6b8121abe543d094c0871f496adade

Source dataset

uspto-grants-2013_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08598174B2