Production method for preparing 2-chloro-5-chloromethylpyridine from benzylamine-n-propionaldehyde

Abstract

The invention provides a production method for preparing 2-chloro-5-chloromethylpyridine from benzylamine-n-propionaldehyde. The method comprises the steps: under a stirring condition, putting n-propionaldehyde into benzylamine-n-propionaldehyde, and cooling to make n-propionaldehyde completely dissolved; and cooling to -90 DEG to -120 DEG C, putting a proper amount of fuming sulfuric acid, heating to 145 to 165 DEG C for 2 h at a uniform speed, and carrying out heat preservation reaction for 2 h, wherein the mass ratio of the substances is benzylamine-n-propionaldehyde:n-propionaldehyde:fuming sulfuric acid=1:(2-4):(5-7). According to the production method for preparing 2-chloro-5-chloromethylpyridine from benzylamine-n-propionaldehyde, 2-chloro-5-chloromethylpyridine is prepared by the way of reducing 2-methylpyridine by fuming sulfuric acid and 5-methylpyridine, a main ingredient of a filter cake is trialkyl amine hydrochloride and can be sold as a by-product after being refined, the shortcoming that a large amount of wastewater is produced in the prior art is overcome, and clean production of the cyclization reaction is achieved.

Description

technical field [0001] The invention relates to the field of production technology of 2-chloro-5-chloromethylpyridine, in particular to a production method for preparing 2-chloro-5-chloromethylpyridine from benzylamine-n-propionaldehyde. Background technique [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...

AI Technical Summary

Problems solved by technology

[0003] 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

[0004] 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

Images