Method for synthetizing DL-cysteine

A synthesis method and cysteine ​​technology are applied in the synthesis field of DL-cysteine, can solve the problems of high production cost, complicated process, low yield and the like, and achieve low production cost, high reaction yield, and high production efficiency. simple craftsmanship

Inactive Publication Date: 2012-07-04
JIANGSU YUANYANG PHARMA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The extraction of cysteine ​​is restricted by the source of raw materials, the yield is low, the energy consumption is high, and a lot of waste liquid is generated during the extraction process, the production cost is high and the process is complicated

Method used

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  • Method for synthetizing DL-cysteine

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preparation example Construction

[0021] A synthetic method for DL-cysteine, comprising the steps of:

[0022] (1) Using ethyleneimine to react with bromine water to obtain 2-bromo-ethyleneimine;

[0023] (2) adding cyanide to the 2-bromo-ethyleneimine prepared in step (1) for heat preservation reaction to obtain 2-cyano-ethyleneimine;

[0024] (3) ring-opening reaction of 2-cyano-ethyleneimine prepared in step (2) with sodium sulfide to generate 2-mercapto-3-aminopropylcyanide;

[0025] (4) Acid hydrolysis of 2-mercapto-3-aminopropanil produced in step (3) at 60°C-90°C to obtain DL-cysteine.

[0026] Wherein, in step (1), the molar ratio of ethyleneimine to bromine water is 1:0.8-1.1; the reaction temperature is 0°C-40°C, and the reaction time is 1-6h; the The preferred reaction temperature is 5°C-30°C, and the preferred reaction time is 2-5h.

[0027] In step (2), the molar ratio of 2-bromo-ethyleneimine to sodium cyanide is 1:1-1.1; the reaction temperature is 0°C-80°C, and the reaction time is 2 -5h; t...

Embodiment 1

[0032] Add 43.4g of ethyleneimine into a 500ml flask, control the temperature at 40°C, add 129.3g of bromine water under stirring, and keep the reaction for 4h. Add 50g of sodium cyanide to the flask, keep it warm for 5 hours, control the temperature to 50°C, add 200ml of acetone, continue stirring for 1 hour, remove the sodium bromide by filtration, and use the filtrate for later use. Put 78 g of sodium sulfide and 150 ml of water into a 1000 ml flask, raise the temperature to 55°C, then add the above filtrate dropwise into the sodium sulfide aqueous solution, after the dropwise addition, keep warm for 2 hours, then add 200g of 98% sulfuric acid dropwise. Heat up to 80°C, heat-preserve and hydrolyze for 4 hours, filter to remove inorganic salts, cool the filtrate to 5°C, filter, wash the filter cake with 100ml of acetone, and dry to obtain 83.5g of DL-cysteine ​​with a yield of 68.39%.

Embodiment 2

[0034] Add 43.4g of ethyleneimine into a 500ml flask, control the temperature at 0°C, add 177.8g of bromine water under stirring, and keep the reaction for 1h. Add 55g of sodium cyanide to the flask, keep it warm for 4 hours, control the temperature to 38°C, add 200ml of acetone, continue stirring for 1 hour, remove the sodium bromide by filtration, and use the filtrate for later use. Put 82g of 98% sodium sulfide and 150ml of water into a 1000ml flask, raise the temperature to 60°C, then add the above-mentioned filtrate dropwise into the sodium sulfide aqueous solution, after the dropwise addition, keep warm for 3 hours, then add 200g of 98% sulfuric acid dropwise. Heat up to 80°C, heat-preserve and hydrolyze for 4 hours, filter to remove inorganic salts, cool the filtrate to 5°C, filter, wash the filter cake with 100ml acetone, and dry to obtain DL-cysteine ​​77g, yield 63.07%.

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Abstract

The invention discloses a method for synthetizing DL-cysteine, comprising the following steps: obtaining 2-bromine-azacyclopropane through the reaction of azacyclopropane and bromine water, obtaining 2-cyano-azacyclopropane through the reaction of the 2-bromine-azacyclopropane and cyanide, obtaining 2-sulfydryl-3-aminopropyl cyanide through a ring-opening reaction of 2-cyano-azacyclopropane and sodium sulfide and obtaining the DL-cysteine through the acid hydrolysis of the 2-sulfydryl-3-aminopropyl cyanide. The method disclosed by the invention has the advantages of mild reaction condition, high reaction yield, adequate raw material source, low production cost and simple production process.

Description

technical field [0001] The invention relates to the technical field of organic chemical synthesis, in particular to a method for synthesizing DL-cysteine. Background technique [0002] Cysteine ​​(cysteine), a common amino acid in living organisms, has a chemical name of 2-amino-3-mercaptopropionic acid, a molecular weight of 157.5, and a molecular formula of HSCH 2 CH(NH 2 ) COOH, one of the sulfur-containing α-amino acids, turns purple when it meets nitroprusside (color due to SH), exists in many proteins, glutathione, and Ag + , Hg + , Cu + Such metal ions can form insoluble thiolates. Cysteine ​​is an aliphatic thiol-containing polar α-amino acid, which is easily oxidized to cystine by air in neutral or alkaline solution. [0003] Cysteine ​​is a naturally occurring amino acid with many uses in food processing, it is mainly used in bakery products as an essential ingredient in dough improvers. Cysteine ​​is a reducing agent, which can promote the formation of glute...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C323/58C07C319/12
Inventor 温建华任举王建峰王敏文司双喜
Owner JIANGSU YUANYANG PHARMA
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