Method for synthesizing N,N dimethyl acetamide in high purity

Abstract

The invention relates to a method for synthesizing N,N-dimethylacetamide. Dimethylamine and glacial acetic acid are neutralized at 35-55°C under normal pressure to generate ammonium acetate salt according to an equivalent molar ratio, and ammonium acetate The salt is added to the reactive distillation tower, and when the amount of the ammonium acetate salt added reaches 1 / 4 to 1 / 3 of the volume of the reactor of the reactive distillation tower, the catalyst is added, and the amount of the catalyst added is 4% of the total weight, heat up, then add ammonium acetate and dimethylamine in the form of bubbling dispersion, add 50g / h of ammonium acetate and 18L / h of dimethylamine continuously, or 100-105g / h of ammonium acetate h and dimethylamine 24L / h, under 170 ~ 180 ℃ atmospheric pressure ammonium acetate decomposed reaction, to obtain N, N-dimethylacetamide and water, and then through continuous atmospheric distillation to obtain N, N-di Methylacetamide, the catalyst is zinc chloride, the conversion rate and selectivity of reactants are high, and the purity reaches 99.95%.

Description

technical field [0001] The invention relates to a method for continuously synthesizing N,N-dimethylacetamide with glacial acetic acid and dimethylamine as raw materials under normal pressure conditions. Background technique [0002] DMAC is a high boiling point, strong polar, non-protonated solvent with strong solvency, excellent thermal and chemical stability, low volatility, not easy to hydrolyze, not easy to change color, low corrosion, low toxicity, etc. It can be widely used in petroleum processing and organic synthesis industries, mainly as a solvent for synthetic fibers such as spandex and acrylic fibers, plastic films, coatings, pharmaceuticals, and catalysts. [0003] In the existing technology for preparing DMAC, there are not only shortcomings such as long reaction time, low production efficiency and low product yield, but also the disadvantages of harsh reaction conditions, high requirements for equipment, high investment costs, and complicated refining process o...

AI Technical Summary

Problems solved by technology

[0003] In the existing technology for preparing DMAC, there are not only shortcomings such as long reaction time, low production efficiency and low product yield, but also the disadvantages of harsh reaction conditions, high requirements for equipment, high investment costs, and complicated refining process of DMAC. It cannot be refined by conventional purification methods, and only qualified products can be obtained through processes such as neutralization, filtration and distillation.

JP123853 (CN1298382 A) provides a technology for synthesizing DMAC with acetic acid and dimethylamine as raw materials under a pressure of 1-5Mpa, which belongs to the high-compression method. The main disadvantage of this process is that it needs to choose a high-pressure device made of a special corrosion-resistant material. , high requirements on equipment, high investment costs, and it is a batch process

The DMAC synthesis process proposed by WO00 / 73251 improves the process through an automatic pressure control valve, but the reaction still needs to be carried out under a pressure of 2-10pisg

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