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Method of rectifying and synthesizing N,N-dimethacrylamide by DMDMAA reaction

A technology of dimethylacrylamide and dimethylpropionamide is applied in the preparation of carboxylic acid amides, chemical instruments and methods, preparation of organic compounds, etc., and can solve the problem of large solvent consumption, low product purity, and many reaction by-products, etc. Problems, to shorten the reaction time, improve the reaction yield, not easy to polymerize the effect

Inactive Publication Date: 2007-09-12
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Although the substitution method has a simple reaction, it has the disadvantages of large amount of solvent and many reaction by-products, resulting in low yield and undesired impurities, and has little industrial value.
The pyrolysis method is mainly to prepare DMAA by pyrolyzing DMDMAA. The process is that DMDMAA reacts with acidic catalysts such as concentrated hydrochloric acid and concentrated sulfuric acid at 210-215°C to produce products. The disadvantage of this method is that the reaction time is long. More than 4 hours, resulting in serious product polymerization, low purity of the generated product, which needs to be further purified by a rectifying device

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0009] Weigh 504g of DMDMAA and add it to the rectifying still, raise the temperature of the tower still to 210-215°C, add 0.72g of polymerization inhibitor p-hydroxyanisole (MEHQ) and 6.0g of catalyst 98% concentrated H to the tower still 2 SO 4 , The tower kettle was kept at a temperature of 210-215° C. for 3 hours, and then the rectifying tower was operated under vacuum. Firstly, under the operating pressure of 0.9KPa, the total reflux operation is carried out at the temperature of the tower kettle at 85-90°C. The total reflux operation is performed for 1 hour. When the gas phase temperature at the top of the tower reaches 47°C, the total reflux operation is completed. Then distill off the front fraction including methyl acrylate, the reflux ratio is 3:1, the operating pressure is 0.9KPa, the temperature of the tower bottom is 85-92°C, the gas phase temperature at the top of the tower is 47-50°C, and the quality of the front fraction is 8g. Under operating pressure is 0.7K...

Embodiment 2

[0011] Weigh 373g of DMDMAA and add it to the rectifying still, raise the temperature of the tower still to 210~215°C, add 0.5g of polymerization inhibitor p-hydroxyanisole (MEHQ) and 5.6g of catalyst 98% concentrated H to the tower still 2 SO 4 , The tower kettle was kept at a temperature of 210-215° C. for 2.5 hours, and then the rectifying tower was operated under vacuum. First, under the operating pressure of 1.0KPa, the temperature of the tower bottom is 85-94°C, and the total reflux operation is performed for 0.5 hours. When the gas phase temperature at the top of the tower is 50°C, the total reflux operation is completed. Then distill off the front fraction including methyl acrylate, the reflux ratio is 3:1, the operating pressure is 1.0KPa, the temperature of the tower bottom is 94-96°C, the gas phase temperature at the top of the tower is 50-54°C, and the quality of the front fraction is 11g. Under the operating pressure of 1.0KPa, the temperature of the tower bottom...

Embodiment 3

[0013] Weigh 310g of DMDMAA and add it to the rectifying still, raise the temperature of the tower to 210-215°C, add 0.39g of polymerization inhibitor p-hydroxyanisole (MEHQ) and 4.65g of catalyst 98% concentrated H 2 SO 4 , The tower kettle was kept at a temperature of 210-215° C. for 2.5 hours, and then the rectifying tower was operated under vacuum. First, under the operating pressure of 1.0KPa, the temperature of the tower bottom is at 84-89°C, and the total reflux operation is performed for 0.5 hours. When the gas phase temperature at the top of the tower is 50°C, the total reflux operation is completed. Then distill off the front fraction including methyl acrylate, the reflux ratio is 3:1, the operating pressure is 1.0KPa, the temperature of the tower bottom is 89-92°C, the gas phase temperature at the top of the tower is 50-51°C, and the quality of the front fraction is 7g. Under the operating pressure of 1.0KPa, the temperature of the tower bottom is 92-97°C, and the ...

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Abstract

This invention relates to a method for synthesizing N, N-dimethylacrylamide by the rectifying 3-dimethylamino-N, N-dimethyl propanamide including: adding DMDMAA into a kettle tower to rise the temperature to 210-215deg.C and adding material liquid and oil of vitriol or acetic acid catalyst and inhibitor,and the kettle tower keeps the teperatue at 210-215 for 2-3h then the rectifying tower operates hydroxyl anisole or hydroquinone in vacuum, which first of all carries out total refluence operation at 80-85deg.C under 0.8-1.0KPa, then evaporates a front fraction including methyl acrylate under operation pressure of 0.5-0.8KPa, 92-97deg.C kettle temperature, 51-52deg.C top gas phase temperature, refluence ratio of 3-5 and the collected product at the top of the tower is DMAA, and the collected un-reacted material DMDMAA returns back to the tank of raw materials.

Description

technical field [0001] The invention relates to a method for synthesizing N,N-dimethylacrylamide by reactive distillation of 3-dimethylamino-N,N-dimethylpropionamide (DMDMAA). It belongs to the preparation technology of N,N-dimethylacrylamide. Background technique [0002] N,N-dimethylacrylamide (DMAA) is an important fine chemical intermediate. Its polymer with other monomers can be widely used in petroleum exploration, printing industry, fine chemical industry, photographic equipment, textile, paper and ethylene industry, etc. due to its good dyeability, hydrolysis resistance, water permeability and adhesion. . There are generally two methods for synthesizing DMAA: one is to retain the double bond to directly replace the carbonyl compound of the propylene skeleton (substitution method); the other is to first protect the double bond and synthesize a multi-substituent carbonyl compound of the propylene skeleton, and then thermally decompose to remove ...

Claims

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Application Information

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IPC IPC(8): C07C233/09C07C231/12
Inventor 汪宝和张跃征井欣吉鹏举张宗礼朱璟张德立
Owner TIANJIN UNIV
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