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Preparation method of 2,5-dimethoxyl-4-chloroaniline

A technology of dimethoxy and chloroaniline, which is applied in the field of preparation of 2,5-dimethoxy-4-chloroaniline, can solve the problems of low cost, high production safety, and good product quality, and achieve production cost Low, less discharge of three wastes, good quality effect

Active Publication Date: 2013-08-28
XIANGSHUI HENRYDA TECH CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in practice, the anti-dechlorination effect of this method is not good, and there are still a large amount (above 0.3%) of dechlorination by-products in the product, and the patented method has high pre-reaction pressure, long total reaction time, and difficult operation. Complex, low product purity
[0004] Looking at the existing hydrogenation reduction methods for preparing 2,5-dimethoxy-4-chloroaniline, none of them can meet the requirements of good product quality and low cost at the same time. And the requirements of three aspects of high production safety

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Add 150g of raw material 2,5-dimethoxy-4-chloronitrobenzene into a 500ml autoclave, add 300ml of solvent methanol, start stirring and heat to 60°C to dissolve; open the autoclave, add 0.8g of morpholine As an anti-dechlorination inhibitor, add 0.5g of Rh-Pt / C catalyst, seal the autoclave, and replace the air in the autoclave with nitrogen and hydrogen in turn; control the temperature at 60~80°C, and feed hydrogen to the pressure of 0.4MPa Start the catalytic hydrogenation reaction; the reaction is completed in 1 hour and 20 minutes, open the autoclave and filter out 0.492g of the catalyst while it is hot, and seal it up for the next batch. The filtrate is cooled to precipitate crystals, and the white crystal product obtained by filtration is 2,5-dimethyl Oxy-4-chloroaniline, the yield is 97.97%, the HPLC content is 99.65%, and the content of dechlorinated by-products is 0.14%; The precipitated product after dimethoxy-4-chloroaniline is preserved for future use.

Embodiment 2

[0029] Add 150g of raw material 2,5-dimethoxy-4-chloronitrobenzene into a 500ml autoclave, add 300ml of recovery solvent methanol, start stirring and heat to 60°C to dissolve it; open the autoclave and add 1.0g partial Ammonium vanadate was used as an anti-dechlorination inhibitor, and 1 g of Ru-Pd / C catalyst was added, the autoclave was sealed, and the air in the autoclave was replaced with nitrogen and hydrogen in sequence; the temperature was controlled at 60-80 °C, and the pressure of hydrogen gas was introduced to Catalyzed hydrogenation reaction started at 0.6 MPa; the reaction was completed in 1 hour and 10 minutes, and the autoclave was opened to filter out 0.48g of the catalyst while it was hot, and it was sealed for future use. The filtrate was cooled to precipitate crystals, and the white crystal product 2,5-dimethyl Oxygen-4-chloroaniline, the yield is 98.28%, the HPLC content is 99.77%, and the content of dechlorinated by-products is 0.09%; the previous step moth...

Embodiment 3

[0031] Add 150g of raw material 2,5-dimethoxy-4-chloronitrobenzene into a 500ml autoclave, add 300ml of solvent methanol (of which 100ml is fresh methanol, and 200ml is ethanol recovered from the first batch of reactions), and start stirring and heated to 60°C to dissolve it; open the autoclave, add 0.8g of morpholine as an anti-dechlorination inhibitor, and add 0.6g of Rh-Pt / C catalyst (0.192g of which is the catalyst recovered from the first batch of reaction), seal Build the autoclave, and replace the air in the autoclave with nitrogen and hydrogen in sequence; control the temperature at 50~70°C, feed hydrogen pressure to 0.6MPa to start the catalytic hydrogenation reaction; the reaction is completed in about 1 hour and 40 minutes, open the autoclave while it is hot Filter out 0.58g of the catalyst and seal it up for use in the next batch. The filtrate cools down to precipitate crystals, and the white crystalline product obtained by filtration is 2,5-dimethoxy-4-chloroanil...

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Abstract

The invention relates to a preparation method of 2,5-dimethoxyl-4-chloroaniline. The method comprises the following steps: performing hydrogenation reduction reaction on 2,5-dimethoxyl-4-chloronitrobenzene used as a raw material and hydrogen in a solvent in the presence of a catalyst and a dechlorination agent to generate the 2,5-dimethoxyl-4-chloroaniline, wherein the catalyst is a supported metal catalyst which consists of carrier carbon, and first and second metals loaded on the carrier carbon. The first metal is selected form one or two of Pd and Pt, while the second metal is selected from one or two of Ru and Rh. The dechlorination agent is morpholine or ammonium metavanadate; after reaction, filtering the catalyst and packaging for the next batch; cooling the filtrate and separating out crystals; and filtering white crystals to obtain the 2,5-dimethoxyl-4-chloroaniline. The preparation method provided by the invention is low in production cost, good in safety and less in three-waste discharge, and the target product obtained is good in quality.

Description

technical field [0001] The invention relates to a preparation method of 2,5-dimethoxy-4-chloroaniline. Background technique [0002] Dimethoxy-4-chloroaniline is an important organic pigment intermediate, which can be used to synthesize Pigment Yellow 83, Pigment Yellow 97, Pigment Red 146, etc. It is widely used in the coloring of high-grade ink, plastic and rubber. At present, the main method of synthesizing 2,5-dimethoxy-4-chloroaniline in industry is to obtain hydroquinone through alkylation, chlorination, nitration and reduction. Among them, iron powder is used for the reaction in the first step of reduction, which has high energy consumption, cumbersome process, poor product quality, and produces a large amount of waste water and waste iron slag pollutants, which are incompatible with the increasingly stringent environmental protection requirements of the current country. [0003] Many domestic scientific research institutions and manufacturers are actively developing...

Claims

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Application Information

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IPC IPC(8): C07C217/84C07C213/02B01J23/46
CPCY02P20/584
Inventor 张正富董志堂黄建新
Owner XIANGSHUI HENRYDA TECH CHEM
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