Method for Continuously Preparing 2-Chloro-5-Chloromethylpyridine Using Microchannel Reactor

Abstract

The invention discloses a method for continuously preparing 2-chloro-5-chloromethylpyridine by a microchannel reactor. The method includes the following steps: simultaneously injecting 2-chloro-5-methylpyridine and chlorine as raw materials into the microchannel reactor for chlorination, collecting a reaction product after the reaction, and crystallizing and distilling the reaction product to obtain the 2-chloro-5-chloromethylpyridine. The method has the advantages that the microchannel reactor is applied to carry out the reaction, the mixing uniformity is high, and the reaction time is greatly shortened; the inner diameter of a microchannel is small while the specific surface area thereof is large, reaction materials are instantaneously mixed uniformly in a precise ratio, the raw materialutilization rate and the product quality are improved, and the selectivity of the product is high, so that the productivity and purity of the product are improved while the production cost is lowered; in addition, the use of organic solvents is avoided in the preparation process, no waste polluting the environment is discharged in the production process, and environmental pollution and harm to the human body are reduced.

Description

technical field [0001] The invention relates to a method for preparing 2-chloro-5-chloromethylpyridine, in particular to a method for continuously preparing 2-chloro-5-chloromethylpyridine using a microchannel reactor. Background technique [0002] 2-Chloro-5-chloromethylpyridine is an important intermediate for the synthesis of high-efficiency insecticides imidacloprid and acetamiprid, and has broad market application prospects. The routes for synthesizing 2-chloro-5-chloromethylpyridine can be divided into two categories: one is the direct chlorination synthesis route using picoline and its derivatives as starting materials, and the other is the ring-closing route. For the pyridine direct chlorination method, the method of branched chain chlorination by 2-chloro-5-methylpyridine in the presence of a catalyst is currently used in the industry to obtain 2-chloro-5-chloromethylpyridine, that is, by 2-chloro-5-methylpyridine. In the presence of carbon tetrachloride or acetoni...

AI Technical Summary

Problems solved by technology

A large amount of DMF and POCl were used in this synthesis reaction 3 , while DMF and POCl 3 Through the reaction, the adduct is formed and dissolved into the toluene system to participate in the reaction. DMF is polymerized and decomposed. After the reaction is completed, it is hydrolyzed and neutralized. The wastewater contains a large amount of amino, phosphoric acid and unreacted DMF, and the COD of the wastewater is as high as 200,000. , while containing a large amount of phosphoric acid, it is difficult to carry out harmless treatment. During the reaction process, due to the long-term heating of 2-chloro-2 chloromethyl-4-cyanobutyraldehyde, decomposition and intermolecular polymerization occur, resulting in the equivalent of 2 -Chlorine-containing polymers with 10%-15% yield of chloro-5-chloromethylpyridine, difficult to harmless treatment

[0004] In addition, the traditional preparation of 2-chloro-5-chloromethylpyridine mostly uses stirred tank reactors, which have long reaction time, large consumption of raw materials, high energy consumption of stirring equipment, multiple sets of reactors at the same time reflect safety problems, and Problems such as many by-products and low yield