23056-36-2

14432-16-7

23056-36-2

The general procedure for the synthesis of 2-chloro-4-nitropyridine-N-oxide from 2-chloro-4-nitropyridine-N-oxide is as follows: referring to the method of Example 17, phosphorus trichloride (4.2 mL, 48.7 mmol) was slowly added to a solution of anhydrous chloroform (25 mL) of 2-chloro-4-nitropyridine-N-oxide (1.70 g, 9.74 mmol) at room temperature. Subsequently, the reaction mixture was heated to reflux and maintained at this temperature for the reaction overnight. Upon completion of the reaction, the mixture was cooled to room temperature. The reaction solution was carefully poured into ice water and the pH was adjusted to 7-8 with alkali and subsequently washed with saturated sodium bicarbonate solution. The aqueous phase was extracted twice with chloroform, all organic phases were combined, washed sequentially with water and brine, dried over anhydrous sodium sulfate, filtered and the organic phase was concentrated. Finally, the product was dried under high vacuum to give 2-chloro-4-nitropyridine (1.2 g, 78% yield) as a solid.