The general procedure for the synthesis of 2-chloro-4-fluoro-5-nitrotoluene from 2-chloro-4-fluorotoluene was as follows: to a stirred concentrated solution of 2-chloro-4-fluorotoluene (2.000 g, 1.383 mmol, Aldrich, direct use), concentrated sulfuric acid (15.0 mL) was slowly added at 0°C, followed by a single addition of potassium nitrate (KNO3, 1.400 g , 1.385 mmol). The reaction mixture gradually changed to a light yellow solution, which was then warmed to 28 °C and stirred at this temperature overnight. Upon completion of the reaction, the mixture was quenched by careful pouring into ice (100 g) and extracted with ethyl acetate (2 x 100 mL). The organic phases were combined, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure to remove the solvent. The resulting oily product was further dried under vacuum to give 2.085 g (80% yield) of the target compound 2-chloro-4-fluoro-5-nitrotoluene as an oil, which was used directly in the next step of the reaction.1H NMR (CDCl3) data were as follows: δ 2.422 (s, 3H), 7.325 (d, 1H, J=10.2 Hz), 7.973 (d, 1H, J= 5.2Hz).
