Synthesis
Into a 500 ml four-necked flask equipped with a thermometer, stirring and reflux condenser, 50 g of phosphorus oxychloride, 14.0 g (0.1 mole) of 2-hydroxy-5-nitropyridine prepared in Example 1, 25.0 g (0.12 Mol) Phosphorus pentachloride,Stir and react at 100-105°C for 5 hours,Then the phosphorus oxychloride was recovered by distillation under reduced pressure, and the remainder was slowly poured into 120 grams of ice water, fully stirred, and then a 40wt% aqueous sodium hydroxide solution was neutralized to a pH of 8-9.Separate the layers, extract the aqueous layer with dichloromethane three times, 60 grams each time, combine the organic phases,Washed with 20 grams of saturated brine, then dried with 2.0 grams of anhydrous sodium sulfate, distilled to recover dichloromethane, and dried to obtain 15.1 grams of 2-chloro-5-nitropyridine (I), yield 95.3%, gas purity 99.8 %.
