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Method for preparing 2,5-dimethoxy-4-chloroaniline by using liquid-phase catalytic hydrogenation method

A technology of dimethoxyl and liquid phase catalysis, which is applied in chemical instruments and methods, preparation of organic compounds, preparation of amino hydroxyl compounds, etc. It can solve the problems of unfriendly environment, achieve low reaction energy consumption, inhibit dechlorination, The effect of high product purity

Inactive Publication Date: 2012-02-08
江苏力达宁化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] At present, the technical route adopted by the industry is to use hydroquinone as raw material, and then undergo O-methylation, chlorination, nitration, iron powder or zinc powder reduction to obtain 2,5-dimethoxy-4-chloroaniline, although This technical route is relatively mature, but due to the iron powder or zinc powder reduction process used in the nitrification reduction process, "iron (zinc) mud" will be produced during the production process, which is an environmentally unfriendly pollutant. Therefore, in today's increasingly stringent requirements for environmental protection, it is necessary to reform the above-mentioned nitro reduction process.

Method used

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  • Method for preparing 2,5-dimethoxy-4-chloroaniline by using liquid-phase catalytic hydrogenation method
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  • Method for preparing 2,5-dimethoxy-4-chloroaniline by using liquid-phase catalytic hydrogenation method

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Embodiment 1

[0024] A method for preparing 2,5-dimethoxy-4-chloroaniline by liquid-phase catalytic hydrogenation method, comprising:

[0025] (a). Add 50 g of 2,5-dimethoxy-4-chloronitrobenzene, 400 g of ethanol, 1.5 g of Raney nickel, and 0.5 g of dimethyl sulfoxide in a high-pressure reactor with a stirring temperature measuring device , dicyandiamide 1g and close the kettle lid. Use N2 to detect leaks and replace the air several times, then add hydrogen to replace to pass, at the same time increase the pressure to 0.7Mpa, raise the temperature to 70°C, and continuously feed hydrogen to maintain the hydrogen pressure at 0.7Mpa. After maintaining the temperature and pressure for 2 hours, the hydrogen pressure did not drop, and the reaction was terminated.

[0026] (b). After filtering the reaction solution to remove the catalyst, add 1.5g of activated carbon and 0.5g of protective agent to the reaction solution, heat up to 85°C, keep the temperature and reflux for 20 minutes and then fil...

Embodiment 2

[0029] A method for preparing 2,5-dimethoxy-4-chloroaniline by liquid-phase catalytic hydrogenation method, comprising:

[0030] (a). Add 2,5-dimethoxy-4-chloronitrobenzene 50g, methanol 600g, Raney nickel 2g, dimethyl sulfoxide 1g, bis 1.5g of cyanamide Close the lid of the kettle, use N2 to detect leaks and replace the air several times, then add hydrogen to replace to pass, at the same time pressurize to 0.6Mpa, heat up to 60°C, continuously feed hydrogen to maintain the hydrogen pressure at 0.6Mpa. After maintaining the temperature and pressure for 3 hours, the hydrogen pressure did not drop any more, and the reaction was terminated.

[0031] (b). After filtering the reaction solution to remove the catalyst, add 2g of activated carbon and 0.5g of protective agent to the reaction solution, raise the temperature to 85°C, keep the temperature and reflux for 20 minutes, then filter while it is hot, discard the activated carbon, and cool the filtrate to 20 ℃ to make it fully c...

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Abstract

The invention relates to a method for preparing 2,5-dimethoxy-4-chloroaniline by using a liquid-phase catalytic hydrogenation method, which comprises the following steps: (a) under the solvent condition, performing a catalytic hydrogenation reaction by taking raneys nickel as a catalyst, dimethyl sulfoxide as an auxiliary agent, organic amine as a dehalogenation inhibitor and 2,5-dimethoxy-4-chloroaniline as a raw material in a high pressure reaction vessel; (b) carrying out decolorizing by using active carbon and filtering to a reaction solution obtained in a step (a), and then adding a protective agent into the reaction solution, cooling, crystallizing and filtering; (c) adding the protective agent into mother liquor filtered in a step (b), concentrating, cooling, crystallizing and filtering, then merging the obtained products filtered in the step (b) and step (c) to obtain the white 2,5-dimethoxy-4-chloroaniline. The invention has the advantages of clean reaction, less pollution, simple process, easy operation, less reaction energy consumption and low cost.

Description

technical field [0001] The invention belongs to the field of compound preparation, and in particular relates to a method for preparing 2,5-dimethoxy-4-chloroaniline by a liquid-phase catalytic hydrogenation method. Background technique [0002] 2,5-dimethoxy-4-chloroaniline, its molecular formula is: C 8 h 10 o 2 NCl, melting point: 118.0-120.0°C. Its structural formula is as follows: [0003] [0004] 2,5-dimethoxy-4-chloroaniline is an important azo pigment intermediate in the dye industry, mainly used in the synthesis of naphthol AS-IRC and naphthol AS-LC. [0005] At present, the technical route adopted by the industry is to use hydroquinone as raw material, and then undergo O-methylation, chlorination, nitration, iron powder or zinc powder reduction to obtain 2,5-dimethoxy-4-chloroaniline, although This technical route is relatively mature, but due to the iron powder or zinc powder reduction process used in the nitrification reduction process, "iron (zinc) mud" ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C217/84C07C213/02
Inventor 岳凤斌
Owner 江苏力达宁化工有限公司
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