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Method of preparing L-methionine by recycling acetyl-DL-methionine

A technology of methionine and acetyl, applied in the field of preparation of amino acids, can solve the problems of environmental pollution, inability to recycle waste water and inorganic salts, and achieve the effects of reducing waste and solids, environmental protection and easy operation.

Active Publication Date: 2015-03-25
BENGBU BBCA MEDICINE SCI DEV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] To sum up, the existing technology cannot recycle the waste water and inorganic salt waste solids produced in the process of preparing L-methionine from acetyl-DL-methionine. After the waste water and waste solids are directly discharged, serious problems will be caused. environmental pollution

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] The production steps are:

[0028] (1) Dissolving 1 kg of aminoacylase in a 30% aqueous solution of acetyl-DL-methionine (containing 60 kg of acetyl-DL-methionine) to obtain a reaction solution, adjust the pH value of the reaction solution to 7.0, and generate at 40° C. Split reaction; after the reaction is complete, vacuum concentrate at 80°C until the water is reduced by 100kg, cool down to precipitate crystals, and filter to obtain 15.75kg of L-methionine crystals with a purity of 99.2% and 80.25kg of mother liquor containing acetyl-D-methionine;

[0029] (2) adding concentration in step (1) gained mother liquor is the NaOH aqueous solution 30kg of 30%, racemization reaction takes place under the condition of pH 12, 100 ℃; 21kg of neutral water, that is, 89.25kg of racemic liquid;

[0030] (3) cooling the racemic solution obtained in step (2) to 50° C., adjusting the pH of the solution to 9.0 with acetic acid, a large amount of crystals were precipitated, filtered t...

Embodiment 2

[0033] The production steps are:

[0034] (1) Dissolving 0.625 kg of aminoacylase in an aqueous solution of acetyl-DL-methionine to obtain a reaction solution, which undergoes a resolution reaction at 40°C. The aqueous solution of acetyl-DL-methionine contains Add water to the mother liquor of acetyl-DL-methionine to 125L; after the reaction is complete, concentrate in vacuo at 80°C until the water is reduced by 62.5kg, cool down to precipitate crystals, and filter to obtain 10kg of L-methionine crystals with a purity of 99.3% and acetyl- The mother liquor of D-methionine 50.5kg;

[0035](2) In step (1) gained mother liquor, add concentration and be 30% NaOH aqueous solution 19kg, racemization reaction takes place under pH 13, 110 ℃ of conditions, described NaOH aqueous solution is obtained with embodiment 1 step (1) After the reaction is complete, keep the temperature, concentrate under reduced pressure, and concentrate 13.5kg of neutral water with pH=7 to obtain 56kg of rac...

Embodiment 3

[0039] The production steps are:

[0040] (1) Dissolving 0.625 kg of aminoacylase in an aqueous solution of acetyl-DL-methionine to obtain a reaction solution, which undergoes a resolution reaction at 40°C. The aqueous solution of acyl-DL-methionine contains Add water to the mother liquor of acetyl-DL-methionine to 125L; after the reaction is complete, concentrate in vacuo at 85°C until the water is reduced by 62.5kg, cool down to precipitate crystals, and filter to obtain 9.5kg of L-methionine crystals with a purity of 99.3% and acetyl -50kg of the mother liquor of D-methionine;

[0041] (2) adding concentration in step (1) gained mother liquor is the NaOH aqueous solution 20kg of 30%, racemization reaction takes place under pH 14, 110 ℃ of conditions, and described NaOH aqueous solution is obtained neutrality with embodiment 2 step (1). Prepared with water; after the reaction is complete, keep the temperature, concentrate under reduced pressure, and concentrate 14kg of neut...

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Abstract

The invention relates to a method of preparing L-methionine by recycling acetyl-DL-methionine. The method comprises the following steps: dissolving aminoacylase in an acetyl-DL-methionine aqueous solution, and carrying out resolution reaction to obtain L-methionine crystals and a mother liquor containing acetyl-DL-methionine; adding a NaOH aqueous solution into the obtained mother liquor, and carrying out racemization reaction to obtain a racemization liquor; cooling the racemization liquor, and regulating a pH value of a solution by using acetic acid to obtain sodium acetate trihydrate crystals and a concentrated solution; adding acetic anhydride into the obtained concentrated solution, and carrying out acylation to obtain the sodium acetate trihydrate crystals and a mother liquor containing acetyl-DL-methionine, wherein the mother liquor, serving as the acetyl-DL-methionine aqueous solution, is used for preparing L-methionine. According to the method disclosed by the invention, acetyl-DL-methionine is recycled, waste liquors and waste solids are reduced in the process of preparing L-methionine, and green production is realized.

Description

technical field [0001] The invention relates to a method for preparing amino acids, in particular to a method for preparing L-methionine by recycling acetyl-DL-methionine. Background technique [0002] Methionine is an important pharmaceutical ingredient, food additive and protein feed fortifier. At present, the synthetic method to produce L-methionine in the market is mainly through the resolution of DL-methionine. The general D, L-methionine resolution technology is enzymatic resolution, that is, splitting acetyl-DL-methionine by aminoacylase to obtain L-methionine. The resolution solution is re-racemized and acylated to obtain acetyl-DL-methionine, and D-methionine is recycled. [0003] In the literature "Research on Acetyl-D-Methionine Racemization Process", Zhang Qingyu and others simulated the process research of methionine resolution liquid for racemization. In the racemization process, the literature method first concentrated the simulated liquid in vacuum to disch...

Claims

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Application Information

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IPC IPC(8): C12P41/00C12P13/12
Inventor 韦亚锋汪洪湖鲍鹤龄
Owner BENGBU BBCA MEDICINE SCI DEV
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