preparation of 4-chloro-3-nitropyridine_industrial additives

preparation background and overview of 4-chloro-3-nitropyridine

pyridine and its derivatives are important intermediates for the synthesis of heterocyclic compounds, pesticides and medicines. it is known that the benzene ring in a compound may have higher biological activity or lower toxicity after being replaced by a pyridine ring. therefore, pyridine and its derivatives are potentially important intermediates for the development of new pesticides and medicines.

4-chloro-3-nitropyridine is a very important class of pyridine derivatives. it can be used as a viscosity regulator and can be used to synthesize the anti-sodium carbonate (decahydrate) ulcer drug pirenzepine and diazepam. heterozoic anti-aids drugs, leukotriene biosynthesis inhibitors, and can be used as drug intermediates for pesticides. therefore, the research on the synthesis of 4-chloro-3-nitropyridine is of great significance. the currently commonly used method is to use 3-nitropyridine as raw material. first, a chlorination reaction occurs under the action of hydrogen peroxide and hydrochloric acid. this method has a simple reaction, but has many by-products and a low product yield.

preparation of 4-chloro-3-nitropyridine

the preparation method of 4-chloro-3-nitropyridine includes the following steps:

(1) mix 5 mol of 4-hydroxypyridine and ionic liquid and stir evenly, add concentrated nitric acid while stirring, continue stirring for 10 minutes, add 1 mol of mesoporous silica, raise the temperature to 95°c, stir for 2 hours, and cool to room temperature. in an ice-salt bath, add concentrated ammonia dropwise while stirring, adjust the ph to 5-7, add desamidomethylpyridinium ionized water, stir until complete precipitation, filter, wash the precipitate with deionized water 2-5 times, and dry it , obtaining 4-hydroxy-3-nitropyridine;

(2) mix 4 mol of 4-hydroxy-3-nitropyridine and 2 mol of phosphorus oxychloride obtained in step (1) and stir evenly. add 1 mol of thionyl chloride dropwise. after the dropwise addition is completed, raise the temperature to 90 °c, reflux for 3 hours. after the reflux is completed, add deionized water, extract with dichloromethane, and then remove the dichloromethane under negative pressure to obtain 4-chloro-3-nitropyridine.