Nitric Acid → 2,3,4-Trifluoro-5-nitrobenzoic acid

Participants

Reaction Steps

To gently stirring concentrated sulfuric acid (50 ml) was added fuming nitric acid (3.4 ml, 0.076 mol). Solid 2,3,4-trifluorobenzoic acid (10.00 g, 0.05565 mol) was added directly in increments. After stirring 45 minutes, the reaction mixture had become an orange homogeneous solution which was then poured over chilled water (400 ml). The resulting aqueous suspension was extracted with diethyl ether (3×200 ml). The combined extracts were dried with anhydrous magnesium sulfate and concentrated in vacuo to yield 12.30 g of a dull, light-yellow solid. Recrystallization from chloroform (50 ml) afforded 9.54 g of the pale yellow microcrystalline product; 78% yield; m.p.; 1H-NMR (400 MHz; DMSO) δ14.29 (broad s, 1H), 8.43-8.38 (m, 1H); 13C-NMR (100 MHz; DMSO) δ162.41, 154.24 (dd, JC-F=270.1, 10.7 Hz), 148.35 (dd, JC-F=267.0, 9.2 Hz), 141.23 (dt, JC-F=253.4 Hz), 133.95, 123.30 (d, JC-F=2.2 Hz), 116.92 (dd, JC-F=18.2, 3.8 Hz); 19F-NMR (376 MHz; DMSO) δ−120.50 to −120.63 (m), −131.133 to −131.27 (m), −153.63 to −153.74 (m).

Provenance & Evidence