Preparation method of 5-chloro-8-hydroxyquinoline and purification method thereof

Abstract

The invention discloses a preparation method of 5-chloro-8-hydroxyquinoline and a purification method thereof, which aims at solving the problem when 4-chloro-2-aminophenol, 4-chloro-2-nitrophenol andglycerol ring are used to obtain 5-chloro-8-hydroxyquinoline, the reaction process is difficult to control, so that a large amount of tar can be generated, the reaction yield is low, the reaction operation is difficult, and a large amount of waste acid is generated after the post treatment. Boric acid and insoluble organic solvents being added into the reaction solution is the innovation of the preparation method, by the method, the acuteness of direct production of acrolein from sulphuric acid and glycerol is mitigated by boric acid, the speed of the acrolein polymerization to generate the tar is reduced, the yield and the safety are effectively improved, and a small amount of an water-insoluble organic solvents can effectively prevent 4-chloro-2-nitrophenol from coagulating on the reactor wall, the problem that it is difficult to control in the process of production operation is solved, which shortens the reaction cycle and improves production efficiency. The preparation method of 5-chloro-8-hydroxyquinoline and purification method thereof has the advantages of less tar, high yield and safe reaction, and can effectively reduce waste acid production and is easy to industrialize.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to a preparation method of 5-chloro-8-hydroxyquinoline and a purification method thereof. Background technique [0002] As a very useful fine chemical intermediate, 5-chloro-8-hydroxyquinoline is widely used in the production of agrochemicals, animal feed, disinfectants and preservatives, etc. At present, 5-chloro-8-hydroxyquinoline is mainly synthesized in the following two ways: 1) 5-chloro-8-hydroxyquinoline is obtained by chlorination of 8-hydroxyquinoline; 2) through 4-chloro-2- Aminophenol, 4-chloro-2-nitrophenol, and glycerol are ring-closed to obtain 5-chloro-8-hydroxyquinoline. Among them, the latter method has readily available raw materials and industrialization, and has been widely used. For example, patent CN102267943 (name: a method for preparing 5-chloro-8-hydroxyquinoline, publication date: 2011.12.07) has disclosed related synthesis process. [0003] However, the...

AI Technical Summary

Problems solved by technology

[0004] 1) The reaction process is difficult to control: during the dripping of sulfuric acid, sulfuric acid reacts violently with glycerin, producing a large amount of acrolein, which may even cause an explosion;

[0005] 2) A large amount of tar will be produced: due to the violent reaction, the acrolein produced by the reaction will self-polymerize into tar, which is difficult to remove during the post-processing of the product and reduces the reaction yield;

[0006] 3) Difficult to control the reaction: 4-chloro-2-nitrophenol, as an oxidant, has a strong sublimation property and is difficult to control during the production operation;

[0007] 4) Post-treatment will produce a large amount of waste acid: the reaction uses concentrated hydrochloric acid to beat the by-products, which will produce a large amount of low-concentration dilute hydrochloric acid, which is difficult to concentrate through physical methods, so that it is difficult to reuse, resulting in a large amount of waste acid, which is not environmentally friendly. economy