Preparation method for 2-chloro-5-chloromethyl pyridine

Abstract

The invention relates to a synthesis method for 2-chloro-5-chloromethyl pyridine, in particular to an innovation on a chlorination addition and cyclization reaction. In the method, the insufficient of preparing the 2-chloro-5-chloromethyl pyridine in a cyclopentadiene-acrolein route is solved; the purpose of utilizing less DMF (Dimethyl Formamide) in the chlorination addition and the cyclization reaction is realized; solid triphosgene or diphosgene or phosgene are adopted to substitute phosphorus oxychloride and other phosphorous chlorination cyclization reagents, therefore, the problem of mass discharge of the DMF and phosphorous waste water in the production course is thoroughly solved; the production cost is reduced; and the cleaner production is realized.

Description

technical field The invention relates to a preparation method of 2-chloro-5-chloromethylpyridine. technical background 2-Chloro-5-chloromethylpyridine is an important intermediate of pesticides and pharmaceuticals. For example: 2-chloro-5-chloromethylpyridine is an important intermediate in the synthesis of important neonicotinoid insecticides imidacloprid, thiacloprid, acetamiprid, nitenpyram, etc., such as European patents EP247477, EP296453, EP685477 , EP235725, EP315826, EP192060, EP244777, EP0386565, EP580553, EP1031566, JP62292765, JP8259568, JP8291171, JP7242633, etc. There are many ways to synthesize 2-chloro-5-chloromethylpyridine. For example, 3-picoline oxidation, selective chlorination route, benzylamine-propionaldehyde route, morpholine-propionaldehyde route, cyclopentadiene-acrolein route. At present, 3-picoline oxidation and selective chlorination routes are mainly used in foreign countries. Most domestic manufacturers mainly use the cyclopentadiene-acrolei...

AI Technical Summary

Problems solved by technology

However, there are obvious disadvantages in this synthetic route: 1. A large amount of N, N-dimethylformamide, referred to as DMF, is needed in the two steps of chlorination addition and cyclization, and every ton of 2-chloro-5-chloro The picoline needs to consume 1-1.2 tons of DMF; 2. A large amount of waste water is produced, 10 tons of high-concentration waste water is produced per ton of 2-chloro-5-chloropicoline, and the COD in the waste water is as high as 180,000-200,000 mg / liter

Wastewater contains a large amount of decomposition products of DMF and part of DMF, and also contains a large amount of phosphorus-containing compounds; 3. The generated wastewater cannot be treated or the treatment cost is extremely high

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