Method of synthesizing 8-hydroxyquinoline

Abstract

The invention discloses a method of synthesizing 8-hydroxyquinoline. Ortho-aminophenol and acrolein are used as raw materials, and hydroquinone is used as a polymerization inhibitor; an addition reaction and a cyclization reaction are carried out under the acidic condition to obtain an intermediate, and a cobalt oxime chelate photocatalyst and an eosin Y photosensitizer are directly added withoutthe need of separation of the intermediate; and an acetonitrile solvent and deionized water are added, under continuous irradiation of visible light, the 8-hydroxyquinoline is obtained through a photocatalytic dehydrogenation oxidation reaction. The reaction process is easy to control, by-products are few, post-treatment is simple, and the generated target product is good in selectivity, high in yield and stable.

Description

technical field [0001] The invention belongs to the field of synthesis of organic intermediates, in particular to a method for synthesizing 8-hydroxyquinoline. Background technique [0002] 8-Hydroxyquinoline is an important intermediate in fine organic synthesis. Its synthesis process, preparation of derivatives, and biological activity are research hotspots in chemistry and medicine. With titration indicators, fluorescent reagents, 8-Hydroxyquinoline and 7-Alkyl Derivatives are metal ion extractants in the metallurgical industry. The complexes formed by its aldehyde derivative Schiff base and many kinds of metal ions have good optical activity, catalytic activity, biological activity and certain anticancer effect. , fluorescent materials and other important intermediates of functional materials, agricultural insecticides and preservatives, textiles, leather, paper, plastics and coatings as preservatives, fungicides and antifungal agents, therefore, 8-hydroxyquinoline The ...

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Problems solved by technology

[0012] Among the four methods, the raw materials of chloroquinoline hydrolysis and aminoquinoline hydrolysis are difficult to obtain, and are only valuable when preparing some 8-hydroxyquinoline derivatives containing special structures, and are not suitable for large-scale industrial production; quinoline Sulfonated alkali fusion, quinoline resources are limited, the sulfonation-alkali fusion method consumes a lot of raw materials and high production costs; the Skraup method uses o-aminophenol and acrolein as raw materials, and o-nitrophenol as an oxidant to synthesize 8-hydroxyquinoline, just as In 2007, our research group reported in "Synthesis of 8-Hydroxyquinoline by Skraup Method" in Volume 24, Issue 1 of "Fine Petrochemical Industry": using o-aminophenol and acrolein as raw materials and o-nitrophenol as oxidant to obtain the target product in one pot 8-hydroxyquinoline, in the reaction system, o-nitrophenol dehydrogenates the intermediate obtained by addition and cyclization of o-aminophenol and acrolein to 8-hydroxyquinoline, and at the same time, it is reduced to the starting material o- Aminophenol, this method has reduced raw material input amount and increased target product yield, is 136% with the yield calculated based on o-aminophenol and o-nitrophenol input amount, but following problem exists in the actual reaction: (1) product The yield is unstable, and occasionally the yield is high; (2) the degree of reduction of o-nitrophenol used as an oxidant is difficult to control. In addition to being reduced to o-aminophenol, it is often also reduced to produce 2-nitrosophenol , 2,2'-dihydroxyazobenzene, 4,4'-dihydroxyhydroazobenzene, especially a large number of by-products such as the highly toxic 2-hydroxyaminophenol (dryl), which increases the difficulty of post-processing; (3 ) When the process is enlarged, the yield of the crude product precipitated by alkali neutralization after the reaction is low, and the residue is more when the crude product is purified by distillation, which greatly reduces the yield of the target product

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