Method for preparing 5-chloro-8-hydroxyquinoline

Abstract

The invention discloses a method for preparing 5-chloro-8-hydroxyquinoline and belongs to the technical field of chemistry. The 5-chloro-8-hydroxyquinoline is prepared from raw material components including 4-chloroonitrophenol, 4-chloroortho-aminophenol, glycerol and concentrated sulfuric acid according to a molar ratio of 4-chloroortho-aminophenol to 4-chloroonitrophenol of 1.6:3.2 and a molar ratio of glycerol to 4-chloroonitrophenol of 2.6:5.2 and a molar ratio of sulfuric acid to 4-chloroonitrophenol of 3:9. The method comprises: dripping sulfuric acid into the components under a condition that the temperature of the solvent is 100 to 170 DEG C; and under the sulfuric acid is dripped completely, promoting the reaction to complete by the following measures and removing part of water generated in reaction under vacuum, or removing part or all water byproduct of the reaction by using benzene, methylbenzene, paraxylene or chlorobenzene as an azeotropic water reducing agent. During after-reaction treatment, industrial concentrated hydrochloric acid is used in place of organic solvent to perform refining treatment to remove pigments and impurities from the product, and the product yield is increased. The method is mainly used for synthesizing cloquintocet-mexyl serving as a herbicide component and can also be used as an animal feed additive, a disinfectant and a metal preservative.

Description

technical field

[0001] The invention relates to the technical field of chemical industry, in particular to a method for preparing 5-chloro-8-hydroxyquinoline. Background technique

[0002] 5-Chloro-8-hydroxyquinoline is mainly used in the synthesis of herbicide component Jieduquine, and is also used as an animal food additive, disinfectant and metal preservative. There are many ways to prepare 5-chloro-8-hydroxyquinoline. The synthetic technical literature of the 5-chloro-8-hydroxyquinoline that is seen in report and disclosure mainly contains: 1., use 8-hydroxyquinoline as raw material, be a solvent with a large amount of glacial acetic acid, prepare 5-chloro-8-hydroxyquinoline with chlorine gas Hydroxyquinoline, the yield is 52.7% (JP162066), the main by-product is 5,7-dichloro-8-hydroxyquinoline. The shortcoming of this technology is that main raw material is expensive, and reaction selectivity is poor, and impurity is many; 2., be raw material with 8-hydroxyquinoline, p...