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Method for preparing isocyanate with low chloride content

A technology of isocyanate and isocyanate solution, which is applied in the purification/separation of isocyanate derivatives, organic chemistry and other directions, can solve the problems of uneconomical, low chlorinated isocyanate derivatives, and complicated processes, and achieves improved reactivity and high selectivity. Effect

Active Publication Date: 2019-11-01
WANHUA CHEM GRP CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] In the prior art, the treatment of crude isocyanate usually reacts with isocyanate, resulting in changes in its chemical structure and properties, affecting downstream use, or the process is complex and uneconomical
At present, there is no technical publication on the treatment of isocyanate products to obtain products with low chlorinated derivatives and low acid content

Method used

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  • Method for preparing isocyanate with low chloride content
  • Method for preparing isocyanate with low chloride content
  • Method for preparing isocyanate with low chloride content

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] 200g hexamethylene diisocyanate in N 2 Under protection, add 200g of compound solvent (the mass ratio of dichloroethane to dimethylformamide is 2:1), add aluminum trichloride after mixing to adjust the pH value to 4, weigh phenol sodium salt and 2- Add 2 g of sodium chlorobenzyl formate powder into the solution (the mass ratio of sodium phenolate to sodium chlorobenzyl formate is 2:1), heat to 60°C, react for 180 minutes and cool to room temperature, filter to remove impurities, and heat the filtrate to Nitrogen gas is passed at 100°C for stripping, and vacuum distillation is carried out after stripping. The absolute pressure of the control system is at 1kpa, and the temperature of the tower kettle is at 145°C to extract isocyanate with low chlorine content.

Embodiment 2

[0055] 200g dicyclohexylmethane diisocyanate in N 2 Under protection, add 400g of compound solvent (the mass ratio of dichloroethane to dimethylformamide is 3:1), add aluminum trichloride after mixing to adjust the pH value to 6, weigh phenol potassium salt and 2- Add 6 g of sodium chlorobenzyl formate powder into the solution (the mass ratio of potassium phenolate and sodium chlorobenzyl formate is 3:1), heat to 80°C, react for 120 minutes and cool to room temperature, filter to remove impurities, and heat the filtrate to 100 Nitrogen at ℃ for stripping, vacuum distillation after stripping, control system absolute pressure at 1kpa, tower kettle temperature at 145°C, to extract isocyanate with low chlorine content.

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PUM

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Abstract

The invention discloses a method for preparing isocyanate with low chloride content. A reaction is performed between a compound organic salt and crude isocyanate under acidic conditions, a precipitateis removed in a simple filtration mode, the acid content is further reduced in an inert gas stripping mode, and a residual solvent is removed in a vacuum distillation mode. Through the method, the content of a chlorinated derivative impurity is reduced to 0.1% or below, the acid content is reduced to less than 10 ppm, meanwhile, side reactions are avoided, and the yield can reach 90% or above; and the chlorine content of the isocyanate obtained by using the method can be reduced, so that preparation of down-stream products is improved obviously.

Description

technical field [0001] The invention relates to a method for purifying isocyanate, in particular to a method for preparing isocyanate with low chlorine content. Background technique [0002] At present, the field of isocyanate is mainly prepared by the phosgene method. The corresponding amines such as hexamethylenediamine are mixed with an inert solvent and then fully mixed with phosgene for phosgenation reaction to obtain a photochemical reaction liquid. The photochemical reaction liquid is passed through phosgene After removal and solvent removal, the crude isocyanate is obtained, and a large amount of chlorinated by-products and acids are produced in the reaction, resulting in a large amount of chlorinated derivatives in the crude isocyanate, especially at the initial stage of system start-up, the increase of side reactions leads to the partial content of chlorinated derivatives High, resulting in high levels of chlorinated derivatives and acids in the product. [0003] ...

Claims

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Application Information

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IPC IPC(8): C07C263/20C07C265/14
CPCC07C263/20C07C265/14
Inventor 周也赵东科杨径靖张宏科王文博徐丹刘榕榕韩海涛肖正正
Owner WANHUA CHEM GRP CO LTD
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