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A method for preparing sulfo-substituted benzimidazoles and derivatives thereof

A technology of benzimidazole and sulfo group, which is applied in the field of preparing sulfo-substituted benzimidazole and its derivatives, can solve the problems of poor selectivity, large consumption, high price, etc., achieve homogenization of strong acid centers, improve synthesis selectivity, The effect of enhancing selectivity

Active Publication Date: 2021-02-19
ANHUI SHENGNUOBEI CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] The existing synthesis method of benzimidazoles is mainly the condensation of aldehydes and o-phenylenediamine, the price of raw material aldehydes such as benzaldehyde is high, and the consumption is large; the sulfonation reaction is accompanied by larger isomers For example, the generation of benzimidazole-4-sulfonic acid compounds leads to low product yield, poor selectivity, and difficulty in isomer separation, which increases the subsequent purification steps and affects the use of the target product.

Method used

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  • A method for preparing sulfo-substituted benzimidazoles and derivatives thereof
  • A method for preparing sulfo-substituted benzimidazoles and derivatives thereof
  • A method for preparing sulfo-substituted benzimidazoles and derivatives thereof

Examples

Experimental program
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Effect test

Embodiment 1-1

[0083] Throw 134g (1.1mol) of benzoic acid into a four-necked flask, then add 2g of p-toluenesulfonic acid, then add 250g of mesitylene, heat the mixture to 150°C, then add 108g (1.0mol) of o-phenylenediamine in one go, Divide the water with the water separator until no water comes out to complete the reaction. The temperature of the reaction solution is lowered to 100°C, and a large amount of solids are precipitated. They are filtered while hot, and the filter cake is vacuum-dried to obtain 143.1 g of the intermediate 2-phenylbenzimidazole with a content of 85.1 %, yield 62.7%.

[0084]

[0085] The liquid chromatogram of 2-phenylbenzimidazole is as follows figure 1 shown. The structure of the product was determined by 1H-NMR analysis. The characteristic peaks: the hydrogen resonance peak on the secondary amino group (12.6ppm, 1H), the 4 Hs of the benzimidazole benzene ring and the 5 Hs of the monosubstituted benzene ring are in the benzene ring area Four groups of reson...

Embodiment 1-2

[0087] Throw 134g of benzoic acid into a four-necked flask, then add 2g of concentrated sulfuric acid, then add 250g of o-dichlorobenzene, heat the mixture to 180°C, add 108g of o-phenylenediamine dropwise, and divide the water with the water separator until no water is released. After the reaction, the temperature of the reaction solution was lowered to 100° C., a large amount of solids precipitated, filtered while hot, and the filter cake was vacuum-dried to obtain 176.1 g of the intermediate 2-phenylbenzimidazole, with a content of 94.1% and a yield of 85.3%.

Embodiment 1-3

[0089] The reaction conditions are the same as in Example 1-2, the only difference is: before adding o-phenylenediamine dropwise in the reaction system, 0.5g of free radical inhibitor 2,2,6,6-tetramethylpiperidine-nitrogen-oxide is added (TEMPO).

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Abstract

The invention discloses a method for preparing sulfo-substituted benzimidazoles and derivatives thereof. The method comprises: taking an organic carboxylic acid A and o-phenylenediamine as raw materials and performing a reflux reaction to generate a benzimidazole compound B; The imidazole compound B is reacted with a sulfonating agent to prepare the sulfo-substituted benzimidazole compound C. During carboxyl-amine group dehydration and cyclization, the yield and content of the intermediate benzimidazole compound B are effectively improved by controlling the ratio of raw materials, selecting a suitable catalyst, and inhibiting the oxidation of o-phenylenediamine; During the sulfonation reaction, by controlling the way of adding raw materials and the selection of specific catalysts, the reaction temperature is reduced, the content and yield of the target product are significantly increased, and the formation of isomers is suppressed. At the same time, the reaction conditions and operation steps of each step are simple, easy to control and easy to realize industrial production.

Description

technical field [0001] The invention relates to the field of fine chemicals, in particular to a method for preparing sulfo-substituted benzimidazoles and derivatives thereof. Background technique [0002] Benzimidazole compounds are heterocyclic compounds containing two nitrogen atoms, which can be used as drug intermediates, anthelmintic drugs for humans and animals, fruit preservatives and ultraviolet absorbers, especially benzimidazole-5-sulfonic acid compounds It can be widely used as a UV absorber. In the prior art, benzimidazole-5-sulfonic acid compounds are synthesized by sulfonation of benzimidazole compounds, but there are the following problems: [0003] The existing synthesis method of benzimidazoles is mainly the condensation of aldehydes and o-phenylenediamine, the price of raw material aldehydes such as benzaldehyde is high, and the consumption is large; the sulfonation reaction is accompanied by larger isomers For example, the generation of benzimidazole-4-s...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D235/18
CPCC07D235/18
Inventor 陈和平徐阳
Owner ANHUI SHENGNUOBEI CHEM TECH
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