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Method for preparing dimethylphenyl isocyanate

A technology of dimethylphenylisocyanate and phenylisocyanate, which is applied in the field of preparation of dimethylphenylisocyanate, can solve problems such as no substantial progress, achieve low production costs, improve the operating environment, and avoid separation operations Effect

Inactive Publication Date: 2010-09-01
TAIYUAN UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Even if it is aniline raw material, it cannot undergo isocyanation reaction with solid phosgene due to the influence of substituents, such as 2,6-dichloro-4-nitroaniline and 2,6-dibromo-4-nitroaniline , the inventor began to use 2,6-dichloro-4-nitroaniline and 2,6-dibromo-4-nitroaniline as raw materials to react with solid phosgene to prepare corresponding isocyanate in April 2008, and designed Different experimental schemes have not made substantial progress after more than a year of research, so it is of practical significance to study the reaction of aniline with different structures and solid phosgene to prepare corresponding isocyanates

Method used

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  • Method for preparing dimethylphenyl isocyanate
  • Method for preparing dimethylphenyl isocyanate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Weigh 27.9g of 3,4-dimethylaniline and 29.7g of solid phosgene and dissolve them in 100mL solvent 1,2-dichloroethane respectively, then control the temperature at 0-5°C, and slowly dissolve the dimethylaniline solution under stirring Add it dropwise to the solid phosgene solution, after the addition is complete, heat up to 75-80°C for reflux reaction for 5 hours. After the reaction, the solvent was removed, and the substrate was distilled under reduced pressure to obtain the product 3,4-dimethylphenylisocyanate with a yield of 81.97% and a product content of 96.91% (HPLC method).

Embodiment 2

[0017] Weigh 26.7g of 3,5-dimethylaniline and 29.7g of solid phosgene and dissolve them in 100mL of solvent 1,2-dichloroethane respectively, then control the temperature at 0-5°C, slowly dissolve the dimethylaniline solution under stirring Add it dropwise to the solid phosgene solution, after the addition is complete, heat up to 75-80°C and reflux for 4 hours. After the reaction, the solvent was removed, and the substrate was distilled under reduced pressure to obtain the product 3,5-dimethylphenylisocyanate with a yield of 91.04% and a product content of 98.56% (HPLC method).

Embodiment 3

[0019] Weigh 24.2g of 2,6-dimethylaniline and 29.7g of solid phosgene and dissolve them in 100mL of solvent 1,2-dichloroethane respectively, then control the temperature at 0-5°C, slowly dissolve the dimethylaniline solution under stirring Add it dropwise to the solid phosgene solution, after the addition is complete, heat up to 75-80°C for reflux reaction for 3 hours. After the reaction, the solvent was removed, and the substrate was distilled under reduced pressure to obtain the product 2,6-dimethylphenylisocyanate with a yield of 90.52% and a product content of 90.91% (HPLC method).

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Abstract

The invention relates to a method for preparing dimethylphenyl isocyanate. Dimethylaniline and solid phosgene are used as raw materials; the molar ratio of the dimethylaniline to the solid phosgene is 2.0 to 2.4; the reaction time is between 3 and 6 hours; a reaction solvent is 1,2-ethylene dichloride; and the reaction temperature is the refluxing temperature of the 1,2-ethylene dichloride. The method, which prepares the dimethylphenyl isocyanate by using the solid phosgene to replace traditional phosgene or diphosgene, and reacting the solid phosgene with the dimethylaniline, has the advantages of simple and reasonable process course, safe and reliable operation, high reaction yield and low production cost, operating environment improvement, environmental pollution reduction, and easy realization of industrialized production.

Description

technical field [0001] The present invention relates to a kind of preparation method of dimethylphenyl isocyanate, specifically, it is a kind of preparation method of using solid phosgene to replace traditional phosgene or diphosgene and dimethylaniline to prepare dimethylaniline , mainly used in the fields of polyurethane, coatings, dyes, leather and pesticides. Background technique [0002] The traditional synthesis methods of phenyl isocyanate include phosgene method, Curtius rearrangement method, haloform β elimination method, one-step carbonyl method, phenylcarbamate thermal decomposition method, etc., among which phosgene method is most commonly used. For example, Zhang Fusheng (Synthetic technology of isocyanate TDI, MDI, etc., Liaoning Chemical Industry, 1996, 2: 14-16) dissolved molten diaminotoluene in chlorobenzene, reacted with phosgene at 35-45 ° C at low temperature, and then heated it at 130 High temperature reaction with phosgene at ℃, after the reaction, us...

Claims

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Application Information

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IPC IPC(8): C07C265/12C07C263/10
Inventor 赵晓霞史宝萍高晓荣温艳珍
Owner TAIYUAN UNIVERSITY OF SCIENCE AND TECHNOLOGY
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