2,3-dichloropyridine synthesis method

Abstract

A Synthesis of 2, 3-dichloro-pyridine, including steps as follows: 1)liquating the raw material of 3-aminopyridine in decuple-twelvefold mass thick alcaine at the condition of mixing, cooling to 4-5 deg C, adding equal mol mass hydroperoxide as raw material, controlling reaction temperature between 6-8deg Cand mixing for 1-2h at the same temperature after adding the things; 2) cooling the solution below 0deg C, adding equal mol mass erinitrit solution as raw material and then preserving heat for 0. 5-1h; 3) controlling the reaction temperature below 0deg C, adding miscible liquids of 0. 15 times mol mass copper chloride as the raw material and duple mass as thick alcaine, then preserving heat for a half hour at least; 4) Returning reactant to ambient temperature and doing extraction by dichloromethane; 5) vacuum distilling the tobacco extract to dry will get product. The intermediate products of the invention are never purified and moved, all the procedures can be done in the same reaction pot and the three step reaction only uses alcaine which contains reactant as solution.

Description

Technical field [0001] The invention relates to a synthesis method of 2,3-dichloropyridine. Background technique [0002] 2,3-Dichloropyridine is an important fine chemical intermediate and is widely used in the fields of medicine and pesticides. Its synthesis technology has not yet been reported in relevant literature in China. There are only two relevant foreign documents: [0003] One is the Japanese patent JP1193246 published on August 3, 1989; its synthetic route is: using 2,3,6-trichloropyridine as raw material and using hydrogen catalytic reaction to prepare it. [0004] Second, the PCT international application WO 2005070888 filed by DuPont of the United States was published on August 4, 2005; the specific route and method are as follows: [0005] 24.4g (0.2mol) nicotinamide is degraded in two temperature stages with sodium hypochlorite in an alkaline solution. At the end of the reaction, it is neutralized with concentrated hydrochloric acid. The maximum amount of ...

AI Technical Summary

Problems solved by technology

[0002] 2,3-Dichloropyridine is an important fine chemical intermediate, widely used in the fields of medicine and pesticides, and its synthesis technology has not been reported in domestic literature so far

[0008] (2) The diazotization and chlorination reactions are carried out in a large amount of oil (organic phase) and water mixture, with large solvent loss and poor operating environment

[0009] (3) Use high-priced copper ions (copper chloride or copper oxide when adding) as catalysts, because the positioning performance during the chlorination reaction is poor, resulting in low purity of the final product

[0010] (4) The chlorination reaction is carried out at high temperature (60°C), and the yield is low due to the decomposition loss of the diazonium salt (it is well known that the diazonium salt is extremely unstable).

[0011] (5) The operation of the whole process is cumbersome, and only the purification of the intermediate product 3-amino-2-chloropyridine has 19 auxiliary processes, resulting in a double increase in equipment investment with the same production capacity and a double decrease in labor productivity

[0012] (6) The consumption of auxiliary raw materials (organic solvents) is large, resulting in high product costs

[0013] (7) The amount of process wastewater is large, and there are 2 reaction mother liquors and 3 washing liquids in the whole process from 3-aminopyridine, which brings pressure to clean production

[0015] (1) The production cost is too high (the comprehensive yield is not high, especially the low labor productivity, which makes developed countries unbearable), and the commercial application value is not high

[0016] (2) The product quality is not high, the appearance is light yellow, and the content is only 98%