Preparation method of 5-chloro-8-hydroxyquinoline

Abstract

The invention discloses a preparation method of 5-chloro-8-hydroxyquinoline, aiming at solving the problems that when the 5-chloro-8-hydroxyquinoline is prepared by using 4-chloro-2-aminophenol, 4-chloro-2-nitrophenol and glycerol as raw materials and adopting a Skraup method in a loop closing way at present, sulfuric acid reacts violently with the glycerol in a process of dropwise adding the sulfuric acid so as to produce a large amount of acrolein, the acrolein self-polymerizes into tar, the tar is not only difficult to remove during the post-treatment of the product, but also reduces the reaction yield, the reaction process is difficult to control, and a great deal of waste acid is produced. According to the preparation method, hydrochloric acid is used as a solvent and the acrolein istaken as a loop closing raw material, so that the step of producing the acrolein by using the sulfuric acid and the glycerol is avoided, the generation of the tar is effectively reduced, and the heatrelease state of the reaction is controlled; furthermore, the problem that impurities are produced due to a sulfonation reaction of the product can be avoided, the product yield and safety are improved, the reaction is easy to control, and industrialization is easily realized; therefore, the preparation method has a higher application value.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to a preparation method of a fine chemical product 5-chloro-8-hydroxyquinoline. Background technique [0002] 5-Chloro-8-hydroxyquinoline is an important fine chemical intermediate, which is mainly used in the production of agrochemical quinine, as well as a disinfectant and preservative, and can also be used as a feed additive. There are many ways to prepare 5-chloro-8-hydroxyquinoline, which are mainly divided into two categories from the raw materials: one is obtained by chlorination of 8-hydroxyquinoline; the other is obtained from 4-chloro-2-aminophenol, 4-Chloro-2-nitrophenol and glycerin are used as raw materials and obtained by Skraup ring closure. [0003] Wherein, when adopting 8-hydroxyquinoline chlorination to prepare 5-chloro-8-hydroxyquinoline, it is necessary to use expensive 8-hydroxyquinoline as a raw material, and use a large amount of hydrochloric acid as a solve...

AI Technical Summary

Problems solved by technology

[0005] 1) The reaction process is difficult to control: during the dripping of sulfuric acid, sulfuric acid reacts violently with glycerin to produce a large amount of acrolein, which may even cause an explosion;

[0006] 2) A large amount of tar is produced: due to the violent reaction to generate acrolein, acrolein self-polymerizes into tar, which is not only difficult to remove during the post-processing of the product, but also reduces the reaction yield;

[0007] 3) The reaction is difficult to control: 4-chloro-2-nitrophenol, as an oxidant, has a strong sublimation property and is difficult to control during production operations;

[0008] 4) Post-treatment produces a large amount of waste acid: the reaction adopts concentrated hydrochloric acid to make pulp to remove by-products, and a large amount of low-concentration dilute hydrochloric acid will be produced. Dilute hydrochloric acid is difficult to concentrate by physical methods, so that it is difficult to reuse, which will lead to a large amount of waste acid. Environmentally friendly and economical