One-step reaction method for preparing 4-nitropyridine-nitrogen oxide and halogenated-4-nitropyridine-nitrogen oxide

Abstract

This invention relates to a preparation method for 4-nitropyridines-nitrogenoxides and halogenated-4-nitropyridines-nitrogenoxides by one step, merging the separated oxidation and nitration into a single step. In the oxidation reaction, acetic anhydride, concentrated sulfuric acid, maleic anhydride and sodium bisulphate are added as catalyser; in nitration reaction, sodium nitrate is added to accelerate reaction. This method shortens the reaction time, especially the oxidation time reduced by half. After nitration reaction, 30~50% sodium hydroxide, instead of solid sodium carbonate, is used to neutralize the resultant solution to directly get the nitration resultants. In this method, the yield is more than 10% higher than that of routine methods and the production cost is cut down meanwhile.

Description

technical field

[0001] The invention belongs to the preparation method of heterocyclic compounds in organic chemistry, especially a one-step reaction preparation method of halogenated-4-nitropyridine-nitrogen oxide Background technique

[0002] Halogenated-4-nitropyridine-nitrogen oxide is obtained by chemical reduction reaction to obtain halogenated-4-aminopyridine, an important intermediate for the synthesis of pesticides, medicines, and cosmetics. Halogenated-4-nitropyridine-nitrogen oxide is derived from Halopyridine, the initial chemical raw material, is prepared by chemical oxidation and then nitration. Due to the harsh conditions of the electrophilic substitution reaction of halopyridine, the direct electrophilic substitution reaction can only obtain the 3-position substitution of the pyridine ring. Product, that is, if the halogenated pyridine is nitrated, only the halogenated 3-nitropyridine can be obtained. In order to make the halogenated pyridine easy to undergo ...