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Method for preparing N-acetylamino acid

A technology of acetyl amino acid and amino acid, which is applied in the field of preparation of N-acetyl amino acid, can solve the problems of low yield of N-acetyl amino acid, difficult effective separation of sodium acetate, large consumption of reagents, etc., and achieves less reagent consumption and easy separation , the effect of reducing production costs

Inactive Publication Date: 2010-06-09
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Alkaline acylation has a high conversion rate, mild reaction conditions and easy control, but consumes a lot of reagents in the production process. In actual production, the molar ratio is amino acid: NaOH: acetic anhydride = 1:5:1.4~1.5, and a large amount of Sodium acetate is difficult to effectively separate, resulting in low yield of N-acetyl amino acid
Moreover, the presence of sodium acetate in the system will bring great difficulties to the subsequent processes in the production of L-amino acids, such as resolution and racemization.

Method used

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  • Method for preparing N-acetylamino acid

Examples

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Embodiment 1

[0015] A preparation method of N-acetylamino acid, which consists of the following steps: first, put 100g of D, L-methionine and 160ml of acetic acid into a dry 500ml Erlenmeyer flask and stir evenly, place the temperature in an electric heating mantle to raise the temperature to 50°C, and keep it warm for 1 hour, 70ml of acetic anhydride was added evenly, and the time of controlling feeding was 1.5 hours, and the temperature was 50° C.; after stirring and insulating for 1.5 hours, sampling was diluted to twice the original value, and monitored with ninhydrin (1% dehydrated alcohol). If the solution is colorless or basically colorless, it can be regarded as the end point; the temperature is controlled at 80°C, the vacuum degree is 0.076MPa, until the distilled liquid volume is about 200ml, and the remaining mass is kept at about 140g; then add 120ml of water, stir and cool down to 20°C, store in refrigerator at 5°C for 10 hours, then suction filter and dry. Using the same meth...

Embodiment 2

[0018] A preparation method of N-acetyl amino acid, which consists of the following steps: first, put 100g of D, L-methionine and 170ml of acetic acid into a dry 500ml Erlenmeyer flask and stir evenly, place the temperature in an electric heating mantle to raise the temperature to 55°C, and keep it warm for 1 hour; 72ml of acetic anhydride was evenly added dropwise, and the controlled feeding time was 3 hours, and the temperature was 55°C; after 1.5 hours of insulation, the sample was diluted to twice the original value, and was monitored with ninhydrin (1% dehydrated alcohol). The colorless or almost colorless solution can be regarded as the end point; once concentrated: the temperature is controlled at 75°C, the vacuum degree is 0.08MPa, the volume of the distilled liquid is about 220ml, and the remaining mass is kept at about 135g; after applying the mother liquor, the second Sub-concentration: the required time is 1 hour, the temperature is controlled below 80°C, the vacuum...

Embodiment 3

[0020] The method of the present invention in 3m 3 It is carried out in an open enamel stirred reactor. The specific process is as follows: First, add 500kg D, L-methionine and recovered 1100L acetic acid into the reactor and stir evenly, the temperature is controlled at 45-60°C, and the jacket is kept warm for 1 hour; at this time, 380L of acetic anhydride is added, and the control time is 5 Hours, the temperature is 50 ℃; keep warm for 3 hours. Concentrate at a vacuum of 0.08MPa and control the temperature at 75°C until the distilled liquid is about 1150L; continue to concentrate after applying the mother liquor: control the temperature below 80°C and vacuum at 0.075-0.08MPa until the distilled liquid is About 750L; finally add 1000L of water, stir and cool down to 20°C, pass through frozen brine to cool down to 5°C, keep warm for 6 hours, precipitate crystals, and filter with suction. The average recovery rate of five batches of continuous application of the mother liquor...

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Abstract

The invention discloses a method for preparing N-acetylamino acid, comprising the following steps of: mixing amino acid and acetic acid in the mol ratio of 1:(4-7), raising temperature to 40-70 DEG C and stirring and keeping the temperature for 1-6 hours; evenly feeding acetic anhydride the mole number of which is equivalent to 1.0-1.4 times that of the amino acid within 1-5 hours and stirring and keeping the temperature for 1-4 hours; rapidly distilling under the condition that the vacuum degree is 0.07-0.08 Mpa and the temperature is 60-90 DEG C until the volume of the distilled liquid is 1.0-1.3 times the adding volume of the acetic acid; and then adding water the mass of which is 1-3 times that of the amino acid, stirring and reducing the temperature to separate out crystals, stading for 1-24 hours, separating solid and liquid and drying the solid. The method consumes few reagents and greatly reduces the production cost; and products are easy to separate and the total yield is high up to 92-98 percent. The generated acetylamino acid has high purity and is beneficial to subsequent technological process.

Description

technical field [0001] The invention belongs to the preparation method of amino acid, in particular to the preparation method of N-acetyl amino acid. Background technique [0002] At present, the acetylation technology of amino acid mainly adopts alkaline acylation. The specific method is: dissolving the amino acid in aqueous sodium hydroxide solution, then adding acetic anhydride at a certain temperature, concentrating the reaction solution after the acylation reaction is completed, and finally crystallizing at low temperature to obtain the product. Alkaline acylation has a high conversion rate, mild reaction conditions and easy control, but consumes a lot of reagents in the production process. In actual production, its molar ratio is amino acid: NaOH: acetic anhydride = 1:5:1.4~1.5, and a large amount of Sodium acetate is difficult to effectively separate, resulting in a lower yield of N-acetylamino acid. Moreover, the existence of sodium acetate in the system will bring...

Claims

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Application Information

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IPC IPC(8): C07B43/06C07C323/59C07C319/20C07C233/47C07C231/02
Inventor 董涛赵林宋正孝毛国柱谭欣
Owner TIANJIN UNIV
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