Reaktion #86711

Reaktionsgleichung

3,5-difluoro-2-(trifluoromethyl)aniline

HBr

NaNO2

→

1-bromo-3,5-difluoro-2-(trifluoromethyl)benzene

Ausbeute 68.0%

Lösungsmittel

H2O

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturdropwise maintaining −5° C
2. 2
   workup.STIRRINGThe resulting mixture was stirred at −5° C. for 1 h
3. 3
   Temperaturto slowly warm to ambient temperature
4. 4
   workup.WAITAfter 4 hours
5. 5
   Extraktionthe resulting solution was extracted with hexanes (3×75 mL)
6. 6
   TrocknenThe combined organics were dried over Na2SO4
7. 7
   Filtrationfiltered
8. 8
   Einengenconcentrated under reduced pressure
9. 9
   SonstigeThe resulting residue was chromatographed over silica gel (40 g Redisep column, pure hexanes)

Vorschrift

A suspension of 3,5-difluoro-2-(trifluoromethyl)aniline (24, 1.0 g, 5.07 mmol) in a 48% aqueous HBr (8 mL) and H2O (8 mL) was stirred at −5° C. for 5 min. To the suspension, NaNO2 (350 mg, 5.07 mmol) was added in a 10 mL aqueous solution dropwise maintaining −5° C. The resulting mixture was stirred at −5° C. for 1 h then CuBr (1.09 g, 7.63 mmol) was added portion-wise and the resulting suspension was allowed to slowly warm to ambient temperature. After 4 hours, the resulting solution was extracted with hexanes (3×75 mL). The combined organics were dried over Na2SO4, filtered, and concentrated under reduced pressure. The resulting residue was chromatographed over silica gel (40 g Redisep column, pure hexanes) to afford 1-bromo-3,5-difluoro-2-(trifluoromethyl)benzene (25) as a light yellow liquid (1.01 g, 68%). 1H NMR (300 MHz, CDCl3) δ 7.34-7.28 (m, 1H), 6.99-6.85 (m, 1H).

Quelle