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Synthesis method for preparing 3, 4-dichloroaniline by refining and hydrogenating o-dichlorobenzene nitride

A technology for o-dichlorobenzene and dichloroaniline, which is applied in the synthesis field of o-dichlorobenzene nitrate refining and hydrogenation to prepare 3,4-dichloroaniline, and can solve the problem of high energy consumption, o-dichlorobenzene nitrate refining and poor performance. The hydrogenation step is cumbersome and consumes a lot of energy, so as to achieve the effect of efficient reaction, continuous process and improved efficiency

Inactive Publication Date: 2021-10-19
徐圣杰
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Problems solved by technology

[0004] Although the above methods have achieved the synthesis of 3,4-dichloroaniline, these methods still have the problems of cumbersome purification and hydrogenation steps of o-dichlorobenzene nitration and high energy consumption.
The crystallization and separation of nitrates requires more than ten hours of process operation to realize the crystallization and solid-liquid separation of materials; rectification separation requires high temperature conditions and high energy consumption
In addition, after hydrogenation of 3,4-dichloronitrobenzene, the solvent usually needs to be distilled off under reduced pressure, which also consumes a lot of energy.

Method used

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  • Synthesis method for preparing 3, 4-dichloroaniline by refining and hydrogenating o-dichlorobenzene nitride

Examples

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Effect test

Embodiment 1

[0039] Mix o-dichlorobenzene nitrate (3,4-dichloronitrobenzene mass accounts for 90%) and n-heptane at a mass ratio of 1:1 for the first time, the mixing and refining temperature is 10°C, and the materials are stirred evenly Filtrate, mix and dissolve the obtained solid and n-heptane for the second time to obtain 3,4-dichloronitrobenzene solution, the mass ratio of n-heptane mixed for the first time to the second time is 1:3; , 4-dichloronitrobenzene solution is preheated to 80°C, and the molar ratio of 1:4 with hydrogen is continuously input into a hydrogenation reactor with a fixed catalyst for reaction. The catalyst is platinum carbon, the reaction pressure is 2.0 MPa, and the reaction time is 80s; After the reaction of the materials, the gas-liquid separation and recovery of hydrogen, 75 ° C high-temperature stratification to obtain 3,4-dichloroaniline, water and n-heptane, n-heptane recovery for the refining process. The purity of the obtained 3,4-dichloroaniline was 99.1...

Embodiment 2

[0041]O-dichlorobenzene nitrate (3,4-dichloronitrobenzene accounts for 95% by mass) and n-octane are mixed for the first time at a mass ratio of 1:3, the mixing and refining temperature is 30°C, the materials are stirred evenly and then filtered , mix and dissolve the obtained solid and n-octane for the second time to obtain 3,4-dichloronitrobenzene solution, the mass ratio of n-octane mixed for the first time and mixed for the second time is 1:2; 3, The 4-dichloronitrobenzene solution was preheated to 75°C, and the molar ratio of 1:3 with hydrogen was continuously input into a hydrogenation reactor with a fixed catalyst for reaction. The catalyst was nickel / silicon dioxide, and the reaction pressure was 2.5MPa. The time is 70s; after the material reaction is completed, gas-liquid separation and recovery of hydrogen, high-temperature stratification at 95°C to obtain 3,4-dichloroaniline, water and n-octane, n-octane recovery for the refining process. The purity of the obtained ...

Embodiment 3

[0043] O-dichlorobenzene nitrate (3,4-dichloronitrobenzene accounts for 91% by mass) and isohexane are mixed for the first time at a mass ratio of 1:2, the mixing and refining temperature is 15°C, and the materials are stirred evenly and then filtered. Mix and dissolve the obtained solid with isohexane for the second time to obtain a 3,4-dichloronitrobenzene solution. The mass ratio of isohexane for the first mixing to the second mixing is 1:4; the 3,4-dichloronitrobenzene The chloronitrobenzene solution is preheated to 100°C, and the hydrogen gas is continuously input into the hydrogenation reactor with a fixed catalyst at a molar ratio of 1:3 for reaction. The catalyst is platinum carbon / alumina, the reaction pressure is 2.0MPa, and the reaction time is 70s After the reaction of the material, the gas-liquid separation is used to recover hydrogen, the temperature is lowered to 35°C to precipitate a solid, and 3,4-dichloroaniline is obtained by filtration. The mother liquor is ...

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Abstract

The invention discloses a synthesis method for preparing 3, 4-dichloroaniline by refining and hydrogenating an o-dichlorobenzene nitride. The method comprises the following steps: (1) mixing o-dichlorobenzene nitride containing 3, 4-dichloronitrobenzene with alkane, and refining to obtain a 3, 4-dichloronitrobenzene solution; (2) continuously inputting the 3, 4-dichloronitrobenzene solution obtained in the step (1) and hydrogen into a hydrogenation reactor fixed with a catalyst, and carrying out hydrogenation reaction; and (3) separating the product 3, 4-dichloroaniline from the hydrogenation material obtained by the hydrogenation reaction in the step (2) in a solid-liquid separation or continuous layering manner, and recovering the mother liquor for replacing part or all of the alkane in the step (1) to refine the o-dichlorobenzene nitride. The invention provides a synthesis method for preparing 3, 4-dichloroaniline by refining and hydrogenating o-dichlorobenzene nitride, which has the advantages of high efficiency, simplicity and convenience in operation and low energy consumption.

Description

technical field [0001] The invention relates to the field of synthesis of 3,4-dichloroaniline, in particular to a synthesis method for preparing 3,4-dichloroaniline through refined hydrogenation of o-dichlorobenzene nitrate. Background technique [0002] 3,4-Dichloroaniline is an important organic intermediate widely used in the fields of dyestuffs, medicines, pesticides, etc. Azo dyes such as Disperse Red 153 and Disperse Red 152. [0003] At present, the domestic method of generating 3,4-dichloroaniline mainly uses o-dichlorobenzene as raw material, and carries out nitration reaction under nitric acid and sulfuric acid to generate 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene. A mixture of benzene, crystallization or rectification to obtain high-purity 3,4-dichloronitrobenzene, catalytic hydrogenation reduction in solvent methanol or ethanol to obtain 3,4-dichloroaniline. For example, patents CN10332650B, CN107973720A, CN109651157A, etc. all propose the method of...

Claims

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Application Information

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IPC IPC(8): C07C209/36C07C211/52
CPCC07C209/365C07C211/52Y02P20/129
Inventor 徐圣杰殷炎
Owner 徐圣杰
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