Nitric Acid → 6-Fluoro-2-methyl-3-nitrobenzoic acid
Reaction equation
[F:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]([CH3:11])[C:3]=1[C:4]([OH:6])=[O:5].OS(O)(=O)=O.[N+:17]([O-])([OH:19])=[O:18]>>[F:1][C:2]1[C:3]([C:4]([OH:6])=[O:5])=[C:7]([CH3:11])[C:8]([N+:17]([O-:19])=[O:18])=[CH:9][CH:10]=1Participants
4
Conditions
- Temperature
- -2.5 °C
Procedure
A solution of 2-fluoro-6-methylbenzoic acid (2 g, 12.98 mmol) in concentrated H2SO4 (15.77 ml, 295.85 mmol) was cooled to −5° C. in an acetone/ice bath in air. A mixture of concentrated nitric acid (1.08 ml, 16.87 mmol) and concentrated H2SO4 (1 ml, 18.76 mmol) was added dropwise to the reaction mixture at −5 to 0° C. over 15 minutes. The pale yellow reaction mixture was stirred at −5 to 0° C. for 30 minutes before being poured onto ice (100 g). The resulting precipitate was filtered and dissolved in EtOAc (50 ml) and the organic phase was washed with deionized water (25 ml) followed by brine (25 ml). The organic phase was dried over MgSO4, filtered and concentrated under reduced pressure to give 2 g (77%) of 6-fluoro-2-methyl-3-nitrobenzoic acid as a white solid. LC-MS 99%, 1.31 min (3 minute LC-MS method), m/z=198.0, 1H NMR (500 MHz, Chloroform-d) δ ppm 8.04 (dd, J=9.1, 5.0 Hz, 1H), 7.16 (t, J=8.6 Hz, 1H), 2.63 (s, 3H).