Preparation method of chlorotoluene

A kind of chlorotoluene, chlorine technology

Pending Publication Date: 2022-07-29
常州新东化工发展有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Because the boiling points of m-chlorotoluene (boiling point 160-162°C) are very close to o-chlorotoluene (boiling point 157°C) and p-chlorotoluene (boiling point 162°C), it is very difficult to separate m-chlorotoluene from chlorinated liquid by rectification. Difficulty, the generated m-chlorotoluene greatly affects the improvement of the purity of p-chlorotoluene
[0004] CN113896612A has reported a kind of adopting iron powder and dibenzothiophene compound as catalyst, the method that catalyzes the reaction of toluene and chlorine to synthesize chlorotoluene, the proportion ratio of o-chlorotoluene in the toluene chloride that this method obtains adopts single-system Lewis catalyst chlorine However, the price of bromo and iododibenzothiophene catalysts used in this method is relatively high, and solids are used as catalysts in industry, so it is difficult to realize automatic feeding of iron powder, and the remaining excess iron powder after the reaction needs to be separated
CN109734551A has reported a kind of adopting active zeolite as main catalyst, sulfide, sulfur monochloride, sulfur dichloride, thiophenol and mercaptan etc. are as cocatalyst catalytic toluene ring chlorination method, in the method product, o-chlorotoluene and The highest mass ratio of p-chlorotoluene is 1.2, but the zeolite catalyst used is easy to pulverize in an acidic environment, which makes it difficult to recycle the catalyst and is not suitable for industrial production

Method used

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  • Preparation method of chlorotoluene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] The plug flow reactor includes a circulating pump 2, a gas-liquid mixer 4, and an inner diameter of 32.0m long pipeline reactor 3 with jacket heat exchange, the inside of pipeline reactor 3 is filled with iron θ ring packing piled up porous iron packing bed; the preparation process of chlorotoluene is as follows:

[0044] 1) after toluene and cocatalyst 2-(phenylthio)thiophene are mixed according to mass ratio 1:0.0005, the mixture is added in pipeline reactor 3 using circulating pump 2, and the upper part of pipeline reactor 3 is continuously extracted using circulating pump 2 material, and into the bottom of the pipeline reactor 3, so that the mixture is forced to mix evenly;

[0045] 2) with the circulating liquid that the circulating pump 2 continuously extracts and the chlorine mass flow ratio be 1:0.055 feeding, and add the pipeline reactor 3 after mixing with the circulating liquid in the gas-liquid mixer 4, and the reaction temperature is 50 ℃. In the reaction...

Embodiment 2

[0049] The difference between this example and Example 1 is that in step 4), 75% to 95% of the high boiling point of the catalyst removal tower 11 tower kettle is recycled to the dechlorination and deacidification kettle in step (3) for reuse. The chlorine content is 0.05%, the high boiling total amount is 1.41%, the purity of ortho-chlorotoluene obtained by rectification is 99.87%, and the purity of p-chlorotoluene is 99.83%.

[0050] As can be seen from the above-mentioned example data, the high boiling amount generated after 75%~95% of the rectification raffinate is recycled and applied is reduced, the m-chlorotoluene content is reduced, and the product purity is improved. It can be seen from this that a certain amount of contained in the high boiling point of the catalyst-removing tower kettle is obtained. The amount of ferric chloride and co-catalyst can be applied to the dechlorination and deacidification kettle at high boiling point, which can further improve the reactio...

Embodiment 3

[0052] The difference between this example and Example 1 is that no catalyst is added to the reaction, and in step 3) sampling and analysis, it is found that the m-chlorine content is 3.13%, the total high-boiling amount is 7.58%, and the obtained o-chlorotoluene has a purity of 98.27%, p-chlorine The toluene purity was 97.35%.

[0053] Since no catalyst is added in this example, the final high boiling amount and the amount of m-chlorotoluene generated by hardening are high, and the product purity is reduced. It can be seen from this that the technical scheme of the present invention uses 2-(phenylthio)thiophene, 3-(phenylthiophene), 3-(phenyl) One or a mixture of thio) thiophene is a catalyst, which can reduce the generation of high boiling, the content of intermediate chlorotoluene in the reaction solution is lower than 0.10% after the reaction, and the purity of p-chlorotoluene obtained by rectification is greater than 99.7%;

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Abstract

The invention relates to a preparation method of chlorotoluene, and belongs to the technical field of chemical material preparation. The method comprises the following steps: mixing toluene with a cocatalyst, then carrying out forced circulation reaction on the obtained mixture and chlorine in a plug flow reactor to obtain a mixed chlorotoluene crude product, carrying out dechlorination, deacidification and catalyst removal, and carrying out rectification separation to obtain o-chlorotoluene and p-chlorotoluene. The chlorotoluene preparation method provided by the invention has the advantages that the process is simple, the reaction process is easy to control, 75-95% of catalyst-containing high-boiling substances in a catalyst removal tower kettle can be recycled, the catalyst utilization rate is high, the discharge amount of wastes and tail gas is small, and the prepared target product has high purity.

Description

technical field [0001] The invention relates to a preparation method of chlorotoluene, belonging to the technical field of chemical material preparation. Background technique [0002] Chlorotoluene is an important fine chemical raw material and a widely used organic chemical intermediate. In recent years, the production of a variety of new pharmaceuticals, pesticides, dyes and other intermediates is based on chlorotoluene as the starting material. These intermediates show a very bright development prospect, and the domestic and foreign markets are unanimously optimistic, and many have become hot development products. [0003] At present, the liquid phase chlorination of toluene is mainly used in industry to produce o-chlorotoluene and p-chlorotoluene. Toluene is chlorinated in liquid phase to generate three monochlorotoluene isomers, namely o-chlorotoluene, m-chlorotoluene and p-chlorotoluene, among which the proportion of m-chlorotoluene is very small, and a small amount o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J19/00B01J19/18B01J19/24B01J3/00B01J3/04C07C17/12C07C25/02
CPCB01J19/0006B01J19/18B01J19/243B01J19/2465B01J3/006B01J3/04C07C17/12C07C25/02
Inventor 孙运林张鹏王丽娟王顺利张驰李景林陶文平
Owner 常州新东化工发展有限公司
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