Method used for smooth and steady preparation of 2-methoxypropandioic acid ethyl methyl ester

Abstract

The invention relates to a method used for smooth and steady preparation of 2-methoxypropandioic acid ethyl methyl ester. The method comprises following steps: (a) methyl methoxyacetate and diethyl oxalate are delivered into a reaction container, and a mixed solution is obtained via mixing; (b) solid sodium methylate is dispersed in diethyl oxalate, an obtained mixture is added into the mixed solution dropwise, and an obtained mixed material is reacted for 2 to 8h at a temperature of 50 to 60 DEG C so as to obtain a reaction liquid; (c) an organic solvent, water, and an acid solution are delivered into another reaction container for mixing, the reaction liquid is added, a temperature of an obtained material is controlled below 15 DEG C, pH value is adjusted to 1 to 2, and the material is allowed to stand so as to obtain a water layer and an organic solvent layer; (d) the organic solvent layer is collected and is subjected to distillation so as to remove the organic solvent, and an obtained product is subjected to decarbonylation at a temperature of 178 to 182 DEG C under a vacuum degree of -0.04 to -0.053MPa for 2 to 6h, and fractions obtained under a vacuum degree of -0.095MPa at a temperature above 170 DEG C are collected. According to the method, solid sodium methylate is dispersed in diethyl oxalate which is not too active, and then the obtained mixture is added into the mixed solution dropwise, so that reaction fierce degree of the whole system after adding of solid sodium methylate can be reduced effectively, and smoothness of the reaction is ensured.

Description

technical field [0001] The invention relates to a preparation method of a sulfonamide intermediate, in particular to a method for stably preparing methylethyl methoxymalonate. Background technique [0002] Sulfonamide, whose chemical name is 4-(p-aminobenzenesulfonyl)-5,6-dimethoxypyrimidine, is generally used for the treatment of inflammation, such as upper respiratory tract infection tonsillitis, bacillary enteritis, skin infection, etc. It can be used in conjunction with other drugs to treat pulmonary tuberculosis and lymphatic tuberculosis. Sulfonamide has gone through several generations of research and development, and its production process has gradually stabilized, specifically the following preparation steps: [0003] step 1): [0004] [0005] Step (2): [0006] [0007] Step (3): [0008] [0009] Step (4): [0010] [0011] [0012] Step (5): [0013] [0014] Wherein, methyl ethyl methoxymalonate is the intermediate prepared in the step ...

AI Technical Summary

Problems solved by technology

However, under the action of solid sodium methoxide, methyl methoxyacetate and diethyl oxalate react violently and release a large amount of heat, which can easily lead to a sharp rise in the temperature in the reactor, resulting in danger, which is not conducive to the safety management of the production workshop

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