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Method for synthesizing 3-chloro-4-methylaniline

A technology of methylaniline and dichloronitrotoluene, applied in chemical instruments and methods, preparation of organic compounds, preparation of amino compounds, etc., can solve problems affecting production efficiency, production capacity, reducing the effective use volume of reactors, and hydrogenation Catalyst poisoning deactivation and other problems, to achieve the effect of good inhibition of dechlorination performance, good lipophilicity and hydrophobicity, and strong resistance to poisoning

Active Publication Date: 2015-02-25
ZHEJIANG UNIV OF TECH +1
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Problems solved by technology

However, the publicly reported liquid-phase catalytic hydrogenation technology (technical process such as figure 1 Shown) there are also two shortcomings: 1) in the chlorination liquid (2-chloro-4-nitrotoluene, p-nitrotoluene, a small amount of dichloronitrotoluene and chlorination catalyst etc. Mixed solution) after repeated washing to neutrality, the raw material 2-chloro-4-nitrotoluene as the catalytic hydrogenation step also needs to be refined and purified, the purpose of which is to remove the entrapped 2-chloro-4-nitrotoluene Iron trichloride and iodine (chlorination reaction catalyst) and chlorine ions (raw material chlorine from chlorination) and other substances in the hydrogenation catalyst are prevented from causing poisoning and deactivation of the hydrogenation catalyst [Journal of Zhejiang Ocean University (Natural Science Edition), 2007, 26(2):198]
Xu Danqian et al [Dye Industry, 2001, 38(1): 16] also found that increasing the ratio of methanol to raw materials can significantly reduce the content of azo oxides and azo compounds, but at the same time the content of dehalogenation by-products has nearly doubled
In addition, the use of solvents will also reduce the effective volume of the reactor, affecting production efficiency and production capacity, and recycling solvents requires a lot of energy. Solvent loss is not only a waste of resources but also pollutes the environment.
The chlorination catalyst and other impurities remaining in the 2-chloro-4-nitrotoluene raw material will also deepen the poisoning of the hydrogenation catalyst under the dispersion of the solvent

Method used

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  • Method for synthesizing 3-chloro-4-methylaniline
  • Method for synthesizing 3-chloro-4-methylaniline
  • Method for synthesizing 3-chloro-4-methylaniline

Examples

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Embodiment 1

[0035] Weigh 10g of activated carbon, the specific surface area of ​​activated carbon is 1500m 2 / g, heat treatment at 500°C for 5h under a hydrogen atmosphere. Then impregnate the activated carbon in 120 ml of 2.0 mol / l NaBr solution, stir at 45° C. for 4 hours, filter, recover the mother liquor for recycling, and wash the filter cake with deionized water until no Br ions are detected. Then the above-mentioned treated activated carbon was formulated into 100ml slurry at 80°C, and the corresponding H 2 PdCl 4 solution, stirred for 5h, with 10% Na 2 CO 3 Solution Adjust the pH of the solution to 7.0, and then control the temperature at 30°C. Stir for 0.5h, filter, and wash with deionized water until no chloride ions are detected. Then reduce at 200° C. for 2 h under a hydrogen atmosphere to obtain the carbon-supported palladium catalyst. Statistical analysis of 500 random palladium particles by a high-power transmission electron microscope shows that 85% of the particle s...

Embodiment 2

[0037] Weigh 10g of activated carbon, the specific surface area of ​​activated carbon is 1200m 2 / g, heat treatment at 400°C for 5h under a hydrogen atmosphere. The activated carbon was then immersed in 120 ml of 2.5 mol / l NaBr solution, stirred at 45°C for 4 hours, filtered, the mother liquor was recovered and recycled, and the filter cake was washed with deionized water until no Br ions were detected. Then the above-mentioned treated activated carbon was formulated into 100ml slurry at 80°C, and the corresponding H 2 PdCl 4 solution, stirred for 6h, with 15% Na 2 CO 3 Solution The pH of the solution was adjusted to 7.0, followed by temperature control at 35°C. Stir for 0.5h, filter, and wash with deionized water until no chloride ions are detected. Then reduce at 200° C. for 2 h under a hydrogen atmosphere to obtain the carbon-supported palladium catalyst. Statistical analysis of 500 random palladium particles by a high-power transmission electron microscope shows that...

Embodiment 3

[0039] Weigh 10g of activated carbon, the specific surface area of ​​activated carbon is 1500m 2 / g, heat treatment at 350°C for 5h under a hydrogen atmosphere. Then this gac is immersed in the KBr solution of the 2.5mol / l concentration of 120ml, 45 DEG C of constant temperature stirring 5h, filter, mother liquor recycles mechanically, and filter cake is washed with deionized water until no Br ion is detected. Then the above-mentioned treated activated carbon was formulated into 100ml slurry at 80°C, and the corresponding H 2 PdCl 4 solution, stirred for 4h, with 10% Na 2 CO 3 Solution The pH of the solution was adjusted to 7.0, followed by temperature control at 35°C. Stir for 1 h, filter, and wash with deionized water until no chloride ions are detected. Then reduce at 250° C. for 2 h under hydrogen atmosphere to obtain the carbon-supported palladium catalyst. Statistical analysis of 500 random palladium particles by a high-power transmission electron microscope shows ...

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Abstract

A method for synthesizing 3-chloro-4-methylaniline is disclosed and comprises: taking a 4-nitrotoluene chlorination liquid as an initial raw material, standing for separating water, so as to obtain a mixture mainly containing 2-chloro-4-nitrotoluene, 4-nitrotoluene and dicloronitrotoluene, directly conveying to a hydrogenation reaction kettle without performing refining purification processing, and performing catalytic hydrogenation reaction under the conditions of not using organic solvents and dehalogenation inhibiters and under the effect of a carbon-supported palladium catalyst, and performing rectification separation on the fully-reacted reduced liquid to obtain 3-chloro-4-methylaniline. A preparation method of the carbon-supported palladium catalyst comprises: firstly processing active carbon in hydrogen atmosphere at 200-800 DEG C, then using a NaBr or KBr solution for dipping to enable Br ion to be supported on the active carbon surface, filtering and washing until no Br ion is detected out; then dipping the processed active carbon in a H2PdCl4 solution, after complete dipping, adjusting the pH value of the solution to 7.0, fully stirring for reaction, filtering and washing with deionized water until no chlorine ion is detected out; and finally performing reduction in hydrogen atmosphere at 30-400 DEG C to obtain the carbon-supported palladium catalyst.

Description

(1) Technical field [0001] The invention relates to a method for synthesizing 3-chloro-4-methylaniline, in particular to a method for synthesizing 3-chloro-4-methylaniline by catalytic hydrogenation. (2) Technical background [0002] 3-Chloro-4-methylaniline is an important pesticide, dye and pharmaceutical intermediate, and it is the key raw material for the synthesis of 2B acid, chlorotoluron, and amphetamine valeramide. Existing synthetic routes mainly take p-nitrotoluene as starting raw material, through chlorination (p-nitrotoluene chlorination generates 2-chloro-4-nitrotoluene), reduction (2-chloro-4-nitrotoluene reduction Generate 3-chloro-4-methylaniline) derived from two-step chemical reaction. Among them, the reduction steps mainly include chemical method (iron powder or sodium sulfide) reduction process [Dye and Dyeing, 2003, 40(1):44] and liquid-phase catalytic hydrogenation reduction process. The chemical reduction process has low yield, poor quality and serio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C209/36C07C211/47C07C211/52B01J23/44
Inventor 李小年卢春山张群峰马磊丰枫吕井辉许孝良俞卫祥顾国萍
Owner ZHEJIANG UNIV OF TECH
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