Method for preparing L-methionine

Abstract

The invention aims to the field of chemical engineering, and relates to a method for preparing L-methionine. According to the method, acetylated saponification liquid is used as production raw material, acid is added into the raw material, the pH is adjusted to be acidic, after reduced pressure distillation, an organic solvent is used for treatment, so that a solution containing D,L-acetyl methionine is obtained, then the organic solvent is removed to obtain D,L-acetyl methionine crystals, and a resolution reaction is performed on the produced D,L-acetyl methionine crystals, so that the L-methionine is obtained; the technology does not need refined D,L-methionine, the soponification liquid for producing the D,L-methionine is used for performing an acetylated reaction, and therefore production cost is reduced; after the acetylation, water is evaporated to dryness, the organic solvent is used for desalting, the yield of the D,L-acetyl methionine reaches 97-99%, and the purity of the D,L-acetyl methionine reaches above 96%; the enzymolysis speed of the D,L-acetyl methionine is higher than that of a traditional method, the obtained L-methionine is good in crystal form and whiteness, the purity reaches above 99.5%, and the total yield of the L-methionine is improved to 78%; according to the technology, a circulation technology is integrated, the design is reasonable, and production cost is reduced.

Description

technical field [0001] The invention aims at the field of chemical industry and relates to a new production method of L-methionine, in particular to a method for producing saponification liquid by using D,L-methionine and jointly preparing L-methionine. Background technique [0002] L-methionine, as a common reagent in biochemical research and a routine nutritional supplement, is also widely used in the adjuvant treatment of pneumonia, liver cirrhosis and fatty liver. At present, a variety of preparation methods of L-methionine have been reported, but most of the preparation methods are still in the laboratory stage, and only a few methods can be used in industrial production later. Among these methods, the usual means are enzymatic resolution or enzymatic cleavage, such as in the U.S. patents of US6114163 and US6524837, which respectively use enzymes to split D, L-acetyl-methionine, and enzymes to cleave D, L-methylthioethyl Hydantoin method. [0003] In the prior art, th...

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Problems solved by technology

This method also has complex operations, high cost, and a certain amount of saline wastewater discharge, and D,L-acetylmethionine cannot be completely recovered.

[0004] There are two shortcomings in the above-mentioned patent reports: 1) In the above-mentioned documents, the raw materials D and L-methionine for the preparation of L-methionine are all purified commercial D, L-methionine, and their purity is 98% Above, this will inevitably lead to an increase in the cost of L-methionine; 2) The separation and purification rate of D, L-acetylmethionine and the recovery and utilization rate of D, L-acetylmethionine waste liquid are low, and there are complex operations and cost High problem; the discharge of waste liquid will also cause serious environmental pollution

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