Preparation method for N-acetyl morpholine

Abstract

The invention belongs to the morpholine product field, and especially relates to a preparation method for N-acetyl morpholine. The method is characterized in that, the steps comprise a synthesis step wherein morpholine and methyl acetate are subjected to a synthesis reaction in a reactor, a crude product N-acetyl morpholine is obtained, and the reaction is carried out at a pressurization pressure of 0.5-1.2MPa and at a temperature of 100-180 DEG C; a flash evaporation step, wherein the crude product N-acetyl morpholine is subjected to flash evaporation in a flash evaporator, flash evaporation light components and flash evaporation heavy components are obtained, the flash evaporation temperature is 110-150 DEG C, and the flash evaporation pressure is 0.15-1.8MPa; a rectification recovery step, wherein the flash evaporation light components are subjected to rectification through a recovery tower, morpholine is separated out after rectification, the flash evaporation heavy components go into a morpholine removal tower, morpholine is removed after rectification; a product rectification step, wherein the components after morpholine removal go into a product rectifier for rectification, and a refined product N-acetyl morpholine is obtained. The morpholine containing components from the recovery tower and the morpholine removal tower can be sent back to the reactor for recirculation reaction. In the method, N-acetyl morpholine with a purity of being more than 99.5% can be prepared, the morpholine content is less than 0.1%, the free acid content is less than 0.05%, the water content is less than 0.02%, and the morpholine total yield is raised.

Description

technical field [0001] The invention belongs to the field of morpholine products, in particular to a preparation method of N-acetylmorpholine. Background technique [0002] N-acetylmorpholine is an important organic chemical product, which is mainly used in the fields of aromatic hydrocarbon extraction, pesticide and pharmaceutical synthesis. The mixture of N-acetylmorpholine and N-formylmorpholine has been used abroad as a special extraction agent for the extraction of aromatics. In terms of pesticide synthesis, it is one of the main raw materials for the synthesis of agricultural fungicides such as dimethomorph and flumorph. In terms of pharmaceutical synthesis, it can be used to synthesize fungicides or as a solvent for extracting biomass. In recent years, N-acetylmorpholine has also been applied in the field of gas purification, especially in the field of high hydrogen sulfide natural gas purification. With the decline of gas quality in the world's exploited gas fiel...

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Problems solved by technology

The description in Chinese patent CN1721415A discloses the use of inorganic alkali or inorganic salt dehydration and deacidification agent to treat the reaction crude product, but this increases the unit operation of filtration, resulting in more cumbersome process

[0017] The main shortcoming of intermittent acetic acid method reaction is: generally use organic water-carrying agent, can increase the cost of solvent recovery thus, and water-carrying agent can take part N-acetylmorpholine product and raw material out simultaneously, reduces yield; By-product water, dehydration treatment must be involved in the refining process of N-acetylmorpholine, which is complicated

At the same time, due to the excessive amount of acetic acid in the reaction, the recovered water contains a small amount of acetic acid, and the treatment of this low-concentration acetic acid aqueous solution—whether it is wastewater treatment or reuse of acetic acid—is uneconomical; The content of free acid (mainly acetic acid) and water in morphine is higher than other methods, and if it needs to be refined, it will consume a lot of energy in the process of dehydration and refining

But there is no report of using this kind of material to react with morpholine to generate N-acetylmorpholine

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