Purification method and purification device of 3, 4-dichloronitrobenzene

A technology of dichloronitrobenzene and a purification method, which is applied in the field of purification methods and purification devices of 3,4-dichloronitrobenzene, can solve the problem of high process risk of solvent method, difficulty in realizing automation, large number of theoretical trays, etc. problem, to achieve the effect of being conducive to continuous automatic production, high production efficiency and simple process

Pending Publication Date: 2021-04-16
ZHEJIANG RUNTU INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The traditional purification methods mainly include solvent method and rectification method. Among them, the solvent method has high process risk, low yield and low purity, and it is difficult to realize automation; if conventional distillation method is used for separation, due to the The boiling point of benzene is relatively high, and it is very close to the boiling point of 2,3-dichloronitrobenzene at 257-258°C. It requires many theoretical plates, low distillation efficiency and high energy consumption.

Method used

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  • Purification method and purification device of 3, 4-dichloronitrobenzene
  • Purification method and purification device of 3, 4-dichloronitrobenzene
  • Purification method and purification device of 3, 4-dichloronitrobenzene

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Effect test

Embodiment 1

[0099] (a) Nitrification step: add mixed acid (98wt% nitric acid, 98wt% sulfuric acid mass ratio is 1:3) dropwise to o-dichlorobenzene at 20°C, keep warm at 60°C to the end, remove the acid water layer in layers, and then add 1500kg of 1% sodium bicarbonate solution, the temperature is 55 ℃, and the water layer is removed by layering to obtain 624kg of nitration product with a purity of 92.59%, which is put into the primary raw material storage tank 6.

[0100] (b) Primary melting and crystallization step: put the nitration product prepared in (a) into three primary melting crystallization kettles 1, 2, and 3 successively at 55° C., each 200 kg, pass through the cold source medium 14 and then cool down to 26 Crystallize at ℃ for 3.5 hours to obtain a primary crystallization product; open the perspiration valve, pass through the heat source medium 13, make the primary crystallization product melt and sweat again, control the heating rate at 3°C / hour, stop heating at 32°C and kee...

Embodiment 2

[0108] (a) Nitrification step: add mixed acid (98wt% nitric acid, 98wt% sulfuric acid mass ratio is 1:3) dropwise to o-dichlorobenzene at 20°C, keep warm at 60°C to the end, remove the acid water layer in layers, and then add 1500kg of 1% baking soda solution, the temperature is 55 ℃, and the water layer is removed by layering to obtain 619kg of nitration product with a purity of 92.38%, which is put into the primary raw material storage tank 6.

[0109] (b) Primary melting and crystallization step: put the primary raw material into three primary melting and crystallization kettles 1, 2, and 3 in sequence of 200 kg each at 60° C., cool to 27° C. and crystallize for 4 hours after passing through the cold source medium 14, Obtain the primary crystallization product; open the perspiration valve, pass into the heat source medium 13, make the primary crystallization product melt and sweat again, control the heating rate at 2.5°C / hour, stop heating at 32°C and keep it warm for 1 hour...

Embodiment 3

[0114] (a) Nitrification step: add mixed acid (98wt% nitric acid, 98wt% sulfuric acid mass ratio is 1:3) dropwise to o-dichlorobenzene at 20°C, keep warm at 60°C to the end, remove the acid water layer in layers, and then add 1500kg of 1% sodium bicarbonate solution, the temperature is 55 ℃, and the water layer is removed by layering to obtain 622kg of nitration product with a purity of 92.56%, which is put into the primary raw material storage tank 6.

[0115] (b) Primary melting and crystallization step: put the primary raw material into three primary melting and crystallization kettles 1, 2, and 3 in sequence of 200 kg each at 60° C., cool down to 28° C. and crystallize for 4.5 hours after passing through the cold source medium 14, Obtain the primary crystalline product; open the perspiration valve, pass through the heat source medium 13, make the primary crystalline product melt and sweat again, control the heating rate at 2°C / hour, stop heating at 33°C and keep it warm for...

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Abstract

The invention relates to a purification method and a purification device of 3, 4-dichloronitrobenzene. The purification method provided by the invention comprises the following steps: a nitrification step: reacting o-dichlorobenzene with mixed acid to obtain a nitrification product; a first-stage melting crystallization step: melting the nitrification product, and then cooling and crystallizing to obtain a first-stage crystallization product; and melting and sweating the primary crystallization product again to obtain primary sweat and 3, 4-dichloronitrobenzene crystals. The process does not need to add a solvent, the process is simple, the obtained product is good in yield and high in purity, and compared with a traditional process, the process has obvious safety and environmental protection advantages; moreover, the purification device is simple in structure and high in production efficiency.

Description

technical field [0001] The invention belongs to the technical field of organic compound purification, and in particular relates to a purification method and a purification device of 3,4-dichloronitrobenzene. Background technique [0002] 3,4-dichloronitrobenzene is a kind of important organic intermediate, can prepare 2-chloro-4-nitroaniline through ammonolysis, can prepare 3,4-dichloroaniline through reduction, and its structural formula is as (I ), the melting point is 43°C, the boiling point is 255-256°C, and the molecular weight is 192. [0003] [0004] 3,4-Dichloronitrobenzene is obtained by nitration of o-dichlorobenzene, and the nitrated product will inevitably produce 2,3-dichloronitrobenzene, but in fact only 3,4-dichloronitrobenzene Only when benzene is purified to >99% can it have industrial practical value. The traditional purification methods mainly include solvent method and rectification method. Among them, the solvent method has high process risk, lo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C205/12C07C201/16C07C201/08B01J6/00
Inventor 陈宝兴顾高炜赵国生王博宁陈伟兴
Owner ZHEJIANG RUNTU INST
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