A kind of production method of methyl acetoacetate

Abstract

The invention relates to a method for producing methyl acetoacetate. The method is characterized by comprising the following steps of: (1) performing esterification reaction of crude diketene and methanol at the temperature of between 20 and 150 DEG C, wherein in the esterification reaction, one of tertiary amine, an ethylidene-amine-containing compound or an alkaline compound is used as a catalyst; and (2) rectifying a product generated in the esterification reaction in the step (1) continuously in four towers under negative pressure to prepare methyl acetoacetate. In the method, the esterification reaction of the crude diketene is adopted, and the diketene is not needed to be rectified and purified, so energy consumption is low, the yield is high, the catalyst is easy to obtain, reaction conditions are mild, the process is safe and a product has high content and the yield of the product is high, and the method is suitable for large-scale industrial production.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, in particular to a production method of methyl acetoacetate. Background technique [0002] Methyl acetoacetate is the fungicide hymexazol / pymethimol / pyrimethol, the insecticide diazinon / masiaphos / pyrimidinox, the herbicide imazethapyr, rodenticide, coumatetate, and warfarin Intermediates of other substances. It can be used as a component of mixed solvents of cellulose ether esters, and can also be used in organic synthesis such as pesticides, medicines, dyes, pigments, and molecular stabilizers. [0003] In the prior art, diketene and methanol are used to react to form methyl acetoacetate. In order to speed up the reaction, a catalyst must be added. However, the traditional method is to use concentrated sulfuric acid as a catalyst, but using concentrated sulfuric acid as a catalyst will corrode the equipment greatly, which is not conducive to long-term production, and the content and ...

AI Technical Summary

Problems solved by technology

[0007] However, this production method also has the following disadvantages: first, the crude diketene is very unstable when heated, safety accidents are prone to occur in the crude diketene distillation process, and the residue produced is also unstable. How to deal with it is also a problem. Diketene production enterprises basically Safety accidents have occurred in this process; secondly, during the distillation of crude diketene, diketene is polymerized, and the yield of diketene is only 80-90%, and the energy consumption is also high

However, because the thick diketene contains acetic anhydride, the acidity is stronger, which weakens the catalytic activity of the weak base catalyst, and the reaction speed is slow. At the same time, the thick diketene content is low, and the thick ester impurities generated by the direct reaction are many. Therefore, simple rectification is not effective. to high quality methyl acetoacetate

Images