Synthesis method of 2, 3-dichloropyridine

Abstract

The invention provides a synthesis method of 2, 3-dichloropyridine, which comprises the following steps: reacting cyclopentanone with hydroxylamine hydrochloride, and taking sodium hydroxide as an acid-binding agent to obtain a compound A; carrying out Beckmann rearrangement reaction on the compound A under the action of thionyl chloride to obtain a compound B; reacting the compound B with sodiumborohydride under the catalysis of cobalt acetate to obtain a compound C; reacting the compound C under the catalysis of ammonium chloride to obtain a compound D; reacting the compound D with chlorineunder the action of azodiisobutyronitrile to obtain a compound E; and reacting the compound E with tert-butyl hypobromite to obtain 2, 3-dichloropyridine. The method is simple in operation steps, theused reaction raw materials are cheap and easy to obtain, the total molar yield is 68.88%, the purity of the produced 2, 3-dichloropyridine is 98.0% or above, the product quality is good, and the method is suitable for industrial production.

Description

technical field [0001] The invention belongs to the technical field of synthesis of pesticide intermediates, in particular to a synthesis method of 2,3-dichloropyridine. Background technique [0002] 2,3-Dichloropyridine is an important fine chemical intermediate, which can be used as a key intermediate in the synthesis of a new type of insecticide - sulfbendamide. [0003] Chinese patent (CN103570609A) discloses a method for preparing 2,3-dichloropyridine, which uses nicotinamide as a raw material to react with sodium hypochlorite to prepare 3-aminopyridine, and then reacts hydrochloric acid and hydrogen peroxide to obtain 2-chloro-3-amino Pyridine, and finally the target product was obtained by Sandmeyer reaction. This method has more side reactions and lower yield. [0004] Chinese patent (CN102086174A) discloses a production method of 2,3-dichloropyridine, which uses 2-chloronicotinamide as a raw material to avoid the problem of many side reactions caused by 2-position...

AI Technical Summary

Problems solved by technology

[0004] Chinese patent (CN102086174A) discloses a production method of 2,3-dichloropyridine, which uses 2-chloronicotinamide as a raw material to avoid the problem of many side reactions caused by 2-position chlorination, but 2 - Chloronicotinamide is not easy to obtain, so the industrialization prospect of this method is not high

This method has no selectivity to 2-position and 6-position chlorine in the hydrogenation process, so there are many side reactions, which seriously affect the yield and purity of the final product

[0009] Chinese patent (CN103145609A) discloses a kind of preparation method of 2,3-dichloropyridine, this method uses 2,3,6-trichloropyridine as starting material, uses ammonium formate as hydrogen donor, but the conversion of this method The yield is low, so the rectification method needs to be adopted in the separation process, and the yield is not high

[0010] In summary, the current synthesis yield of 2,3-dichloropyridine is low and the production cost is high. At present, domestic research on the synthesis of 2,3-dichloropyridine has not yet achieved satisfactory results, and many processes involve diazo chemical reaction, which is highly dangerous. Under the current domestic chemical industry policy, it is difficult for such a process to be approved by the safety supervision department for production. Not allowed to exceed 2000L

At present, the safety supervision departments in Shandong and Jiangsu generally only approve the reaction scale of less than 1000L, and it is not allowed to install multiple diazotization reactors in one workshop, so the output of a single batch is low, which limits the increase in production capacity

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