Manufacturing method of glycine
I. Introduction
Glycine is an important raw material for the production of chemicals, which is widely used in the fields of medicine, food and agriculture. Therefore, it is of great significance to study the manufacturing methods of glycine to improve the production efficiency, reduce the cost and improve the purity of products. In this paper, we will introduce the manufacturing methods of glycine, including ammonium chloride method, Strecker's method and Hein's method.
II. Ammonium Chloride Method
Ammonium chloride method is one of the main methods for the production of glycine, and its principle is to make ammonium chloride react with urotropin under alkaline condition to produce glycine salt, and then acidify with hydrochloric acid to get glycine. The specific operation steps are as follows:
1. Prepare alkaline solution with urotropine and sodium hydroxide, add ammonium chloride, pass carbon dioxide gas under stirring, control the reaction temperature at 50-60℃, and react to produce glycine salt.
2. The reaction solution was filtered to remove impurities such as unreacted urotropin and sodium chloride to obtain glycinate solution.
3. The glycine salt solution was acidified with hydrochloric acid, controlling the pH at 2-3 to precipitate glycine.
4. Filter, wash and dry the precipitated glycine to obtain the finished product.
The advantage of the ammonium chloride method is that the raw material is easy to obtain, the operation is simple and the cost is low. However, the production process of this method produces a large amount of waste gas and waste water, which is more polluting to the environment.
Third, Strecker's method
Strecker's method is an improved ammonium chloride method, which is based on the principle of adding formaldehyde and sodium cyanide on the basis of the ammonium chloride method to make the reaction more complete and improve the yield and purity of glycine. The specific operation steps are as follows:
1. Prepare urotropin, sodium hydroxide and formaldehyde into an alkaline solution, add ammonium chloride and sodium cyanide, pass carbon dioxide gas under stirring, control the reaction temperature at 60-70 ℃, and the reaction generates glycine salt.
2. The reaction solution was filtered to remove impurities such as unreacted urotropin and sodium chloride to obtain a glycinate solution.
3. The glycine salt solution was acidified with hydrochloric acid, controlling the pH at 2-3 to precipitate glycine.
4. The precipitated glycine was filtered, washed and dried to obtain the finished product.
The advantage of the Strecker method is that it improves the yield and purity of glycine and reduces the emission of exhaust gases and wastewater. However, the method uses toxic raw materials such as sodium cyanide, which poses a risk to the health of the operator and environmental safety.
Four, Haine method
Haine method is a new type of glycine manufacturing method, which is based on the principle of generating glycine and formaldehyde by making 5-hydroxymethylhydantoin hydrolyzed under acidic conditions. The specific operation steps are as follows:
1. Formulate 5-hydroxymethylhydantoin with sulfuric acid to form an acidic solution, and heat it to 80-90℃ to generate glycine and formaldehyde by the reaction.
2. The reaction solution was cooled to room temperature, sodium hydroxide solution was added, and the pH was adjusted to neutral to precipitate glycine.
3. The precipitated glycine is filtered, washed and dried to obtain the finished product.
The advantages of the Haine method are mild reaction conditions, simple operation and high purity of the product. Meanwhile, the method avoids the use of toxic raw materials, which is more friendly to the health of operators and environmental safety.
V. CONCLUSION
In summary, ammonium chloride method, Strecker's method and Hine's method are common methods for the manufacture of glycine. Different methods have their own advantages and disadvantages, and the selection of an appropriate manufacturing method requires comprehensive consideration based on specific circumstances. In the future, with the increasing awareness of environmental protection and the continuous progress of technology, more environmentally friendly, efficient and safe methods of glycine manufacturing will be more widely used.
