Preparation method for 2-chloro-5-chloromethyl pyridine

Abstract

A process for preparing 2-chloro-5-chloromethylpyridine shown as Fig. 1 is disclosed.

Description

technical field [0001] The invention relates to a preparation method of 2-chloro-5-chloromethylpyridine. technical background [0002] 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 cyclope...

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Problems solved by technology

[0004] 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

[0005] At present, the output of imidacloprid in my country reaches 20,000 tons per year, and most of them are produced by the cyclopentadiene-acrolein route. Nearly 20,000 tons of DMF or its decomposition products are discharged to the environment every year, and nearly 200,000 tons per year High-concentration phosphorus-containing wastewater is discharged into the environment, which has caused great harm to the environment. The Chinese government pays special attention to it, requiring companies to rectify within a time limit, and the state also invests funds in technical research

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