Trifluoroacetic acid → 1,2-Difluoro-5-methyl-3-nitrobenzene
Reaction equation
[F:1][C:2]1[CH:3]=[C:4]([CH3:9])[CH:5]=[CH:6][C:7]=1[F:8].[N+:10]([O-])([O-:12])=[O:11].[NH4+].FC(F)(F)C(O)=O.[OH-].[Na+]>>[F:1][C:2]1[CH:3]=[C:4]([CH3:9])[CH:5]=[C:6]([N+:10]([O-:12])=[O:11])[C:7]=1[F:8]Participants
5
Procedure
3,4-Difluorotoluene (9.00 g, 70.3 mmol), ammonium nitrate (6.75 g, 84.3 mmol) and trifluoroacetic acid (25 ml) were stirred at ambient temperature for 18 h. The resulting solution was made basic to pH>10 with 5 N sodium hydroxide and, after cooling to ambient temperature, extracted with diethyl ether (3×40 ml). The combined organic layers were washed with brine (40 ml) and dried over anhydrous sodium sulfate. The filtrate was concentrated in vacuo. The crude product was purified by silica gel column chromatography, eluting with hexanes/ethyl acetate (9:1), to afford 3,4-difluoro-5-nitrotoluene (4.63 g, 40%) as a light yellow oil. 1H-NMR δ (400 MHz, CDCl3) 7.94 (1H, dd, J=9.9, 7.3 Hz), 7.17 (1H, dd, J=10.3, 7.6 Hz), 2.61 (3H, s).