Preparation method of D,L-2-hydroxy-4-methylthio butyric ester

Abstract

The invention belongs to the field of chemical industry, relates to preparation of D,L-2-hydroxy-4-methylthio butyric ester chemical products, and in particular relates to a preparation method of D,L-2-hydroxy-4-methylthio butyric ester based on silicone sulfonic acid as a catalyst. The method comprises the following step: performing an esterification reaction on D,L-2-hydroxy-4-methylthio butyric acid and an alcohol which are taken as raw materials so as to obtain the D,L-2-hydroxy-4-methylthio butyric ester, wherein the silicone sulfonic acid is taken as the catalyst and the alcohol contains 1 to 12 carbon atoms during the esterification reaction. The silicone sulfonic acid taken as the catalyst is simple to synthesize; and the raw material of the silicone sulfonic acid is cheap and easily-available and high in catalytic activity. The catalyst can be repeatedly recycled in a simple filtration mode, so that the production cost is saved; the corrosion of equipment, caused by sulfuric acid, phosphoric acid and the like, is avoided. The process is high in yield, wherein the conversion rate can reach 95% or more; the subsequent treatment is simple after the reaction is finished; the atom economy of the whole reaction is high, namely, other wastes except water are not generated.

Description

technical field [0001] The invention belongs to the field of chemical industry and relates to the preparation of D,L-2-hydroxy-4-methylthiobutyrate chemical products. Background technique [0002] Methionine is the first limiting amino acid for poultry. Methionine additives commonly used in feed mainly include powdered D,L-methionine (DLM) and methionine hydroxyl analog (HMB). Methionine additives can fully provide protein synthesis, decomposition and growth in animals. Required L-Methionine. Methionine hydroxy analogs are divided into liquid methionine hydroxy analogs and solid methionine hydroxy analogs calcium. Methionine hydroxy analogue is a substance with methionine biological activity, besides the function of methionine, it also has functions such as acidifier. Although the liquid methionine hydroxy analog has no amino group, it can still be metabolized into L-methionine in vivo to participate in in vivo metabolism. [0003] The chemical name of the methionine hydr...

AI Technical Summary

Problems solved by technology

Existing D,L-2-hydroxy-4-methylthiobutyrate preparation technology scheme can be roughly divided into three categories: the first category is to use D,L-2-hydroxy-4-methylthiobutyrate salt as raw material, such as U.S. Patent No. 3761518 and U.S. No. 3850987 disclose that under the catalysis of hydrogen chloride gas, D, L-2-hydroxyl-4-methylthiobutyrate (calcium salt, sodium salt, potassium salt, ammonium salt etc.) react with alcohol (methanol, ethanol, isopropanol, butanol, etc.) to prepare D,L-2-hydroxy-4-methylthiobutyrate; the preparation process is cumbersome and the cost is high , not conducive to industrialization and large-scale production

The second type is to use 2-hydroxy-4-methylthiobutyronitrile as a raw material, hydrolyze it under the action of sulfuric acid, and obtain D, L-2-hydroxy-4-methylthiobutyrate through esterification , such as Chinese patent CN1166630C discloses that 2-hydroxy-4-methylthiobutyronitrile is used as a raw material to obtain 2-hydroxy-4-methylthiobutyronitrile by hydrolysis with sulfuric acid, and then esterified with alcohol under the action of sulfuric acid , to obtain D, L-2-hydroxyl-4-methylthiobutyrate; the yield of this process method is low, and the consumption of reaction media such as concentrated sulfuric acid, organic solvent, water is relatively large in the process, not only increasing the production Cost, and the discharge of waste liquid and waste gas is also relatively difficult, which is not an environmentally friendly and green production process

The third category is D, L-2-hydroxyl-4-methylthiobutyric acid directly esterified with alcohol under the catalysis of concentrated sulfuric acid or phosphoric acid, as disclosed in U.S. Patent No. 6,660,880B2 under the catalysis of concentrated sulfuric acid, D , L-2-hydroxyl-4-methylthiobutyric acid and isopropanol to prepare D, the technical scheme of L-2-hydroxyl-4-methylthiobutyric acid isopropyl ester; Under the catalysis of D,L-2-hydroxy-4-methylthiobutyric acid and alcohol (methanol, ethanol, isopropanol, butanol, etc.) to prepare D,L-2-hydroxy-4-methylthiobutyric acid The technical scheme of ester; although the product yield of this method is high, the purity of the product is not high enough, the content of ester in the product can only reach 92%, and the product contains higher dimers and reaction raw materials, and the reaction will produce a large amount of Acid-containing wastewater is more corrosive to equipment and consumes more acid

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