The general procedure for the synthesis of 2-chloro-5-fluoro-4-nitrotoluene from 2-chloro-5-fluorotoluene was as follows: to a stirred concentrated solution of 2-chloro-5-fluorotoluene (0.500 g, 3.46 mmol, Lancaster, for direct use) was added H2SO4 (5.0 mL) slowly at 0 °C. Subsequently, KNO3 (0.350 g, 3.46 mmol) was added all at once. The reaction mixture was gradually warmed to 28 °C and stirred at this temperature overnight. Upon completion of the reaction, the mixture was quenched by pouring it into ice (50 g) and extracted with ether (2 x 50 mL). The combined ether layers were dried with anhydrous Na2SO4 and subsequently concentrated under reduced pressure to remove the solvent. The obtained oily product was further dried under vacuum to give 0.616 g (94% yield) of 2-chloro-5-fluoro-4-nitrotoluene as an oil, which was used directly in the subsequent reaction.1H NMR (CDCl3) data were as follows: δ 2.459 (s, 3H), 7.193 (d, 1H, J=11.1 Hz), 8.083 (d, 1H, J= 6.6Hz).
