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Method for preparing 5-(2-methylmercapto-ethyl)-hydantoin by utilizing crude hydrocyanic acid gas

A technology of methylthioethyl and hydantoin, applied in the chemical industry, can solve the problems of limited industrial application, no purification treatment operation, high production cost, etc., to save production time, stable properties, and simple equipment Effect

Active Publication Date: 2013-11-27
NINGXIA UNISPLENDOUR TIANHUA METHIONINE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] However, in the reports of these documents, no matter which method is adopted to synthesize 5-(2-methylthioethyl)-hydantoin, relatively pure hydrocyanic acid or its salts are required, the production cost is high, and the limitation is limited. its application in industry
In addition, the above-mentioned preparation method obtains a solution of 5-(2-methylthioethyl)-hydantoin, which not only contains 5-(2-methylthioethyl)-hydantoin, but also contains Polymers of methionaldehyde, sodium carbonate, and unreacted ammonium carbonate, etc., need to be further purified to obtain high-purity, high-yield 5-(2-methylthioethyl)-hydantoin, In the above-mentioned documents, there is no efficient purification treatment operation

Method used

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  • Method for preparing 5-(2-methylmercapto-ethyl)-hydantoin by utilizing crude hydrocyanic acid gas

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] The hydrocyanic acid mixed gas I from the hydrocyanic acid synthesis tower was detected. The composition of the hydrocyanic acid mixed gas I was: 8.87% hydrocyanic acid gas, 3.88% water vapor, 1.64% ammonia gas, 1.13% hydrogen gas, nitrogen gas 76.01%, oxygen 1.48%, carbon monoxide 5.67%, carbon dioxide 1.13%, methane 0.39%.

[0043] Hydrocyanic acid mixed gas I passes through a 75% sulfuric acid tower to absorb ammonia and water vapor in the mixed gas to obtain hydrocyanic acid mixed gas II. After testing, its composition is: hydrocyanic acid gas 9.35%, hydrogen gas 1.57%, Nitrogen 79.44%, Oxygen 1.71%, Carbon Monoxide 5.79%, Carbon Dioxide 1.50%, Methane 0.64%.

Embodiment 2

[0045] Pass hydrogen cyanide mixed gas II into 223.3g of 94.5% methional, which contains 3.3g of pyridine. React under normal pressure, control the reaction temperature to 45°C, the ventilation rate to 300L / min, absorb the tail gas with sodium hydroxide, and monitor the residual amount of methionaldehyde by HPLC. When the residual amount of methionaldehyde is less than 0.5%, it is the end of the reaction, and the feeding can be stopped. A total of 270.64 g of light yellow liquid was obtained, the content of 2-hydroxy-4-methylthiobutyronitrile was 98%, and the residual hydrocyanic acid was 0.5%. The obtained 2-hydroxy-4-methylthiobutyronitrile together with its reaction solution (ie, 2-hydroxy-4-methylthiobutyronitrile reaction system) was stored at 3°C ​​for 120 days without any decomposition.

Embodiment 3

[0047] Pass hydrogen cyanide mixed gas II into 222.2g of 94.5% methional, which contains 2.2g of pyridine. React under normal pressure, control the reaction temperature to 40°C, the ventilation rate to 280L / min, absorb the tail gas with sodium hydroxide, and monitor the residual amount of methionaldehyde by HPLC. When the residual amount of methionaldehyde is less than 0.5%, it is the end of the reaction, and the feeding can be stopped. A total of 269.54 g of light yellow liquid was obtained, the content of 2-hydroxy-4-methylthiobutyronitrile was 98%, and the residual hydrocyanic acid was 0.07%. The obtained 2-hydroxy-4-methylthiobutyronitrile together with its reaction solution were stored at 3°C ​​for 120 days without any decomposition.

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Abstract

The invention relates to a method for preparing 5-(2-methylmercapto-ethyl)-hydantoin by utilizing crude hydrocyanic acid gas and relates to the field of chemical industry. The method disclosed by the invention comprises the following steps of: completely reacting hydrocyanic acid mixed gas made by adopting an Ann method with methylmercapto propionaldehyde to obtain a 2-hydroxyl-4-methylmercapto-butyronitrile reaction system under the catalytic action of organic alkali; and sufficiently reacting the 2-hydroxyl-4-methylmercapto-butyronitrile reaction system with ammonium bicarbonate in a water medium to obtain 5-(2-methylmercapto-ethyl)-hydantoin. Due to adoption of raw materials which are not rectified or purified, the method disclosed by the invention is short in production time, high in production efficiency and low in production cost; the prepared 2-hydroxyl-4-methylmercapto-butyronitrile reaction system is steady in property and can be stored for a long time; and 5-(2-methylmercapto-ethyl)-hydantoin with high purity and high yield can be obtained through simple separation and purification operations under the synergistic effect of other substances in reaction liquid.

Description

technical field [0001] The invention aims at the field of chemical industry and relates to a method for preparing 5-(2-methylthioethyl)-hydantoin by using crude hydrocyanic acid gas. Background technique [0002] 5-(2-methylthioethyl)-hydantoin, also known as 5-[2-(methylthio)ethyl]hydantoin, is widely used in medicine and chemical industry, and is the preparation of D,L-methionine, L- Methionine and other important intermediates. [0003] In theory, the preparation of 5-(2-methylthioethyl)-hydantoin is known. In general, the starting materials can be divided into three categories: [0004] 1) Methionaldehyde, hydrocyanic acid, carbon dioxide and ammonia (or ammonium bicarbonate); [0005] 2) Methionaldehyde, sodium or potassium cyanide, carbon dioxide and ammonia (or ammonium bicarbonate); [0006] 3) 2-Hydroxy-4-methylthiobutyronitrile with carbon dioxide and ammonia (or ammonium bicarbonate). [0007] Specifically, The Chemistry of the Hydantoins.Chem.Rev.46(1950)422-...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D233/76C07C323/60C07C319/20
Inventor 吴传隆王用贵秦岭丁永良朱丽利杨帆陈宏杨郑道敏
Owner NINGXIA UNISPLENDOUR TIANHUA METHIONINE CO LTD
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