Synthesis
General procedure for the synthesis of 2,6-dichloro-3-methyl-5-nitropyridine-1-oxide from 2-chloro-5-methyl-3-nitropyridine-1-oxide: 2-chloro-5-methyl-3-nitropyridine-1-oxide (4.0 g, 21.2 mmol) was suspended in phosphorus triclosan (ca. 20 mL) and the reaction was heated to reflux temperature for 3 hours. After completion of the reaction, the reaction mixture was carefully poured into preheated water and cooled to room temperature. It was extracted with ethyl acetate (3×), the organic phases were combined, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give 4.5 g of brown solid. The crude product was purified by fast column chromatography (dichloromethane as eluent and 5% ethyl acetate in heptane solution as elution system) to give 3.56 g (81% yield) of off-white solid. The product was analyzed by GC-MS (EI+) with m/z = 189 and purity >95%.
