Synthesis
The general procedure for the synthesis of 2,3,4-trifluoro-6-nitroaniline using N-(2,3,4-trifluorophenyl)acetamide as starting material was as follows: concentrated nitric acid (1.25 mL) was added slowly and dropwise to a solution of sulfuric acid (14 mL) of 2,3,4-trifluoroacetanilide (4.34 g) obtained from step 1 under ice bath conditions. The reaction mixture was maintained under stirring for 4 hours. Subsequently, crushed ice was added to the reaction mixture and the precipitated yellow solid was collected by filtration to afford 2,3,4-trifluoro-6-nitroaniline (1.56 g, 35% yield). The infrared spectrum (IR, cm1, pure) of the product showed characteristic absorption peaks located at 3483, 3361, 1664, 1600, 1540, 1515. nuclear magnetic resonance hydrogen spectroscopy (1H NMR) data: δ 6.10 (broad single peak, DO exchangeable, 2H), 7.80 (multiple peaks, 1H). Mass spectra (EI-MS) showed molecular ion peak m/z: 192 (M), and fragment ion peaks m/z: 175, 119.
References
[1] Journal of Medicinal Chemistry, 1995, vol. 38, # 22, p. 4367 - 4379
[2] Patent: WO2004/37765, 2004, A1. Location in patent: Page 8
[3] Journal of Fluorine Chemistry, 2003, vol. 121, # 2, p. 171 - 175