Preparation and recycling method of pyridine hydrochloride_Industrial additives

Background and overview of preparation and recycling methods of pyridine hydrochloride

Pyridine hydrochloride, as an important pharmaceutical intermediate and fine chemical raw material, has a wide range of applications and broad market prospects. In medicine, pyridine hydrochloride, an important pharmaceutical intermediate, can be used to synthesize erythromycin methyl.

Preparation and recycling method of pyridine hydrochloride

(a) At room temperature, drop concentrated hydrochloric acid into calcium chloride particles to obtain hydrogen chloride, and pass the hydrogen chloride gas through a concentrated sulfuric acid scrubber bottle and a buffer bottle to obtain dry hydrogen chloride gas;

(b) Place the four-necked flask equipped with a stirrer, thermometer, reflux condenser and air inlet pipe in a cold water bath, add pyridine and dichloromethane to the flask, start stirring and pass in dry hydrogen chloride gas; keep The reaction temperature is 35°C, producing white pyridine hydrochloride;

(c) Stop stirring, filter pyridine hydrochloride and dichloromethane, the filtrate is dichloromethane, and the filter cake is pyridine hydrochloride. Put the filter cake into a vacuum dryer and dry it for 2 hours to obtain the finished product pyridine hydrochloride. Salt.

Preparation and recycling methods of pyridine hydrochloride

CN201110391906.7 reports a method for recovering and recycling pyridine from pyridine hydrochloride, a waste product in the production of chloromethyl isopropyl carbonate. It includes the following process steps: put pyridine hydrochloride and water into a container in a ratio of 1:2, stir ferrocene boric acid, and obtain a pyridine hydrochloride aqueous solution. Put the pyridine hydrochloride aqueous solution and 2 times the pyridine hydrochloride liquid caustic soda into an enamel reaction kettle, stir thoroughly and react to form pyridine and sodium chloride aqueous solution. The above-mentioned pyridine and sodium chloride aqueous solutions are automatically separated in a static state. The upper layer is pyridine with water and the lower layer is sodium chloride aqueous solution. Take out the pyridine with water in the upper layer and use precipitation method to remove impurities, and use polishing method to remove the remaining water to obtain the finished product. The sodium chloride aqueous solution is sent to the concentration pot for concentration to obtain the finished sodium chloride product. The above-mentioned finished pyridine can be sent to the chloromethyl isopropyl carbonate production process line as one of the raw materials for recycling to produce chloromethyl isopropyl carbonate. The invention not only reduces the waste of resources, does not pollute the environment, but also greatly reduces the production cost of chloromethyl isopropyl carbonate and improves the economic benefits of the enterprise.

References

[1][Chinese invention] CN201710496639.7 A method for synthesizing pyridine hydrochloride

[2][Chinese invention] CN201110391906.7 Method for recovering pyridine from waste pyridine hydrochloride and recycling trifluoromethylbenzene boric acid