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Preparation and purification method and purification device of m-tolyl isocyanate

A technology of tolyl isocyanate and a purification method, which is applied in the field of chemical equipment, can solve problems such as human control errors and poor reaction stability, and achieve the effects of reducing the reaction of side reactions, improving reaction stability, and improving product quality and yield

Pending Publication Date: 2022-03-25
UPCHEM CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] 3. The reaction stability is poor, and there are human control errors
[0006] In addition, what the existing preparation method obtains is a crude product of aromatic isocyanate, which needs further purification treatment, and there is no purification method for aromatic isocyanate in the prior art

Method used

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  • Preparation and purification method and purification device of m-tolyl isocyanate
  • Preparation and purification method and purification device of m-tolyl isocyanate

Examples

Experimental program
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Effect test

Embodiment 1

[0031] A method for preparing and purifying m-toluidine isocyanate, the preparation method mainly comprising the following steps: 1) mixing m-toluidine and xylene in a mixing tank at a mass ratio of 1:2.5 to prepare m-toluidine The solution is ready for use; 2) Add solid phosgene and xylene in a mass ratio of 1:2.5 to the reaction kettle, and heat up to dissolve; the molar ratio of m-toluidine to solid phosgene is 1:0.3; 3) Wait for the reaction kettle When the internal temperature reaches 90-110°C, add the m-toluidine solution prepared in the above step 1) dropwise into the reaction kettle, so that m-toluidine and solid phosgene generate m-toluidine hydrochloride and unstable The intermediate product m-toluenecarbamoyl chloride, the intermediate product m-toluenecarbamoyl chloride is dehydrochlorinated to obtain m-toluene isocyanate; the dropwise addition time is 1h, and after the dropwise addition is completed, it is refluxed and kept for 1.5h; the reaction process is monitor...

Embodiment 2

[0036] A method for preparing and purifying m-toluidine isocyanate, the mass ratio of m-toluidine to xylene is 1:3.5, the mass ratio of solid phosgene to xylene is 1:3.5, and the mass ratio of m-toluidine to solid phosgene It is 1:0.4. All the other are with embodiment 1. The purification device is the same as in Example 1. The yield of the prepared m-tolyl isocyanate is 91%, and the product content is ≥99.5%.

Embodiment 3

[0038] A method for preparing and purifying m-tolyl isocyanate, the mass ratio of m-toluidine to xylene is 1:4.5, the mass ratio of solid phosgene to xylene is 1:4.5, and the mass ratio of m-toluidine to solid phosgene It is 1:0.5. All the other are with embodiment 1. The purification device is the same as in Example 1. The yield of the prepared m-tolyl isocyanate is 95%, and the product content is ≥99.5%.

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Abstract

The invention discloses a preparation method, a purification method and a purification device of m-tolyl isocyanate. The preparation method comprises the following steps: 1) preparing an m-toluidine solution in a mixing kettle for later use; 2) adding triphosgene and a solvent into the reaction kettle, and heating for dissolving; 3) when the temperature in the reaction kettle reaches 60-130 DEG C, dropwise adding an m-toluidine solution; the dropwise adding time is 0.5-1.5 hours, and the reflux heat preservation time is 0.5-1.5 hours; the reaction process is monitored by a DCS (Distributed Control System); and carrying out three-stage distillation purification on the obtained m-tolyl isocyanate reaction mixed solution. The yield of the obtained m-tolyl isocyanate product can reach 95%, and the product content is greater than or equal to 99.5%. According to the invention, the low-toxicity chemical triphosgene and the solvent are adopted, and material metering, conveying and operation parameters are all controlled by DCS (Distributed Control System); a one-step method is adopted for synthesis, reaction conditions are mild, and efficiency is high; and a three-stage distillation technology is adopted for purification, so that the product quality and yield are improved.

Description

technical field [0001] The invention relates to a preparation, purification method and purification device of m-tolyl isocyanate, belonging to the field of chemical equipment. Background technique [0002] M-tolyl isocyanate is an important intermediate of medicine, pesticide and polymer material, widely used in the synthesis of substituted urea, carbamate pesticide and medicine. The synthesis of m-toluyl isocyanate can be made by one-step reaction with m-toluidine and phosgene in an inert solvent medium, such as Chinese patent CN102119145A; using phosgene as an acylating agent, because phosgene is a highly toxic chemical substance, in the production There are strict precautions and regulations in transportation, storage and use, and the protection of operators during production is also very strict. There are following disadvantages in the prior art: [0003] 1. Phosgene is a highly toxic chemical, which is difficult to measure accurately and may cause potential safety haz...

Claims

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Application Information

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IPC IPC(8): C07C263/10C07C265/12C07C263/20B01D3/02B01D3/10B01D3/14
CPCC07C263/10C07C263/20B01D3/146B01D3/02B01D3/10C07C265/12
Inventor 夏剑锋夏晨东李兆亮陈映波周裕民陈海芳胥林延
Owner UPCHEM CHINA
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