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Method for purifying p-phenylenediamine by using zone melting of microwave device

A technology of p-phenylenediamine and regional smelting, which is applied in the purification/separation of amino compounds, organic chemistry, etc., can solve the problems of high precision requirements for multi-stage sweating crystallization temperature, low product output, and affecting product quality, etc., to achieve Thorough enrichment, high product yield and high degree of automation

Active Publication Date: 2019-01-18
扬州独角兽知识产权服务有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] In the process of melting and crystallization, the product yield is low and the output of the product is not high. Keeping high temperature for a long time has a certain impact on product quality. Multi-stage sweating crystallization requires high temperature accuracy. Amplitude affects product quality and other shortcomings

Method used

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  • Method for purifying p-phenylenediamine by using zone melting of microwave device
  • Method for purifying p-phenylenediamine by using zone melting of microwave device
  • Method for purifying p-phenylenediamine by using zone melting of microwave device

Examples

Experimental program
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Effect test

Embodiment 1

[0025] After hydrogenation of p-nitroaniline, solvent removal, decoking, delightening and rectification obtain p-phenylenediamine crude product, the main content is 99.5% (mass percentage), and the main impurity is o-phenylenediamine, the content is 0.48 % (mass percentage content), other impurity content is 0.02% (mass percentage content), since the rectification process is after decoking, most of the heavy components have been extracted with tar, other impurities in the crude product are relative to p-benzene Diamine is a light component with a slightly lower boiling point and is difficult to remove by rectification;

[0026] Crystallization: Replace the quartz glass column 1 with nitrogen until the oxygen content is lower than 100ppm, put the molten solution of p-phenylenediamine crude product 10 into the quartz glass column 1 while it is hot, and cool down under the protection of nitrogen to crystallize. The inner diameter of the quartz glass column 1 is 2cm, the thickness...

Embodiment 2

[0031] The difference from Example 1 is that the regional melting and regional crystallization steps are repeated 3 times to further enrich the impurities to the bottom of the quartz glass column 1, and the final step of crystallization is to melt the p-phenylenediamine in the quartz glass column 1 from the bottom , melt the material at a height of 15cm from the bottom, and discharge 10% p-phenylenediamine raffinate by total weight. The p-phenylenediamine content in the raffinate is 95.1%. The distilled product can be used as feed material in the crystallization step, and the remaining p-phenylenediamine is melted and discharged, cooled and crystallized into slices to obtain the finished p-phenylenediamine, which has a p-phenylenediamine content of 99.99% to 99.992%;

Embodiment 3

[0032] Embodiment 3: The difference from Example 2 is in the final step of crystallization section: melting the p-phenylenediamine in the quartz glass column 1 from the bottom, melting the material at a height of 30 cm from the bottom, and discharging 20% ​​p-phenylenediamine by total weight The raffinate, the content of p-phenylenediamine in the raffinate is 97.5%. This p-phenylenediamine raffinate is applied mechanically in the rectification operation, and the product after rectification can be used for the feed of the crystallization step, and the remaining p-phenylenediamine Discharge after melting, cool and crystallize into slices to obtain the finished product of p-phenylenediamine, the content of which is 99.995% to 99.999%.

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Abstract

The invention provides a method for purifying p-phenylenediamine by using zone melting of a microwave device. The method comprises the following steps: a crystallizing step, a zone melting step, a zone crystallizing step and a finished product slicing step; the method is characterized in that impurities can be enriched through carrying out at least once zone melting on crystals of a p-phenylenediamine crude product in a local part, and the impurities can be finally discharged out of a system; heating is carried out by utilizing vibration among molecules through a microwave heating way, the heating is more uniform, and the phenomena that since a traditional heating mode is in heat transfer from the outer part, too much heat is transmitted to a vertical direction, mutual permeability betweena crystallizing layer and a melting layer is caused, and enrichment of the impurities is influenced cannot be generated. Compared with a traditional purifying method, the method provided by the invention has the advantages that the energy consumption is low, the impurities can be completely removed, the yield of products is high, the error-tolerant rate of operation is high, the quality of the products is stable, an operating process is simple, the automation degree is high, no waste is generated, pollution cannot be generated, and the like.

Description

technical field [0001] The invention relates to a method for purifying a compound, in particular to a method for purifying p-phenylenediamine. Background technique [0002] P-phenylenediamine, also known as Wuersi D, is one of the simplest aromatic diamines, and is also a widely used intermediate, which can be used to prepare azo dyes, high molecular polymers, and can also be used to produce fur Dyeing agent, rubber anti-aging agent and photo developer, and p-phenylenediamine is also a sensitive reagent commonly used to detect iron and copper. [0003] Usually, p-phenylenediamine is obtained by hydrogenation reduction of p-nitroaniline after ammonolysis of p-nitrochlorophenyl. In order to obtain high-purity p-phenylenediamine raw materials, the p-phenylenediamine products obtained by reduction need to be purified and refined. Conventional Rectification often requires a relatively high theoretical plate and a high reflux ratio, which can meet the requirements of a certain pu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C209/84C07C211/51
CPCC07C209/84C07C211/51
Inventor 张宾张阵
Owner 扬州独角兽知识产权服务有限公司
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