Preparation method of high-content 2-hydroxy-4-(methylthio) butyl calcium

Abstract

The invention relates to a preparation method of high-content 2-hydroxy-4-(methylthio) butyl calcium. The content of 2-hydroxy-4-(methylthio) butyl calcium prepared by the traditional synthesis method is lower. The preparation method provided by the invention comprises the following steps of: adding 2-hydroxy-4-methionine nitrile with content higher than 99.0% used as a raw material in concentrated HCl (hydrochloric acid) for carrying out hydrolysis reaction; after the reaction is finished, regulating pH with alkali till pH is between 7.8-8.0, cooling, crystallizing and filtering to obtain a 2-hydroxy-4-(methylthio) butyric amide crude product; recrystallizing with water to obtain high-content 2-hydroxy-4-(methylthio) butyric amide; and dissolving the high-content 2-hydroxy-4-(methylthio) butyric amide in water, adding excess Ca(OH)2 and directly hydrolyzing at 80-100 DEG C to generate 2-hydroxy-4-(methylthio) butyl calcium. The yield of the preparation method is very high, and the content of the prepared 2-hydroxy-4-(methylthio) butyl calcium is higher than 99.0%.

Description

[0001] technical field [0002] The invention relates to the field of compound synthesis, in particular to a method for preparing high-content calcium 2-hydroxy 4-methylthiobutyrate. Background technique [0003] Methionine cannot be synthesized in animals and needs to be ingested from food. It is the first limiting amino acid. Adding it to the feed can promote the growth of poultry and livestock, increase the amount of lean meat, and shorten the feeding cycle. 2-Hydroxy 4-methylthiobutyric acid (LMA) is a methionine analogue, which can be absorbed and converted into methionine by animals, and its effect is equivalent to 65% to 88% of that of methionine. At present, LMA is added in ruminant and livestock and poultry feed, and its addition amount is 0.1-0.5%. According to relevant statistics, in recent years, the demand for methionine in the world has grown at a rate of 4% per year, while that in my country has grown at a rate of 7% per year. [0004] According to literatu...

AI Technical Summary

Problems solved by technology

There are problems in this method: 1. It is difficult to carry out the reaction thoroughly; 2. The product is difficult to dry, because D, L-2-hydroxy-4-methylthiobutyric acid has 23~24% polymers, and these polymers are somewhat It exists in the form of lactone and anhydride, and these polymers are difficult to react with solid Ca(OH) 2 Or CaO reacts, and finally adsorbs on the surface of the product, causing the product to be difficult to dry and affecting the quality of the product

The problems in this method mainly include: 1. During the esterification reaction between 2-hydroxy-4-methylthiobutyric acid and alcohol, 10-50% of the raw material 2-hydroxy-4-methylthiobutyric acid is added If sulfuric acid or p-toluenesulfonic acid is used as a catalyst, some acids will inevitably be brought into the subsequent reaction. Once these acids react with calcium hydroxide, the resulting calcium salt has a very high viscosity and is not easy to remove. It is very inconvenient in the industrial operation process. Product quality is also greatly affected

2. During the esterification reaction between 2-hydroxy-4-methylthiobutyric acid and alcohol, the amount of alcohol added is 10 to 40 times the amount of D, L-2-hydroxy-4-methylthiobutyric acid, The use of a large amount of alcohol will consume a lot of heat energy in the subsequent treatment process, which will greatly increase the production cost in the industrial process

The main problem of this method is that 2-hydroxyl-4-methylthiobutyronitrile is unstable in an alkaline environment and is very easy to polymerize. Although 98.5% of -hydroxyl-4-methylthiobutyrate calcium can be obtained, the yield rate not reported