Manufacturing Methods of Mercaptoacetic Acid
Mercaptoacetic acid (TGA for short) is an organic compound containing sulfhydryl group (-SH) and carboxyl group (-COOH), which is widely used in the fields of medicine, pesticide and cosmetics. In the field of raw materials for chemical production, there are mainly the following manufacturing methods for mercaptoacetic acid:
1. Acetaldehyde method
The acetaldehyde method is the main method for the production of mercaptoacetic acid, and its reaction principle is that under alkaline conditions, acetaldehyde and hydrosulfuric acid undergo an addition reaction to generate mercaptoacetic acid salts, which are then acidified to obtain mercaptoacetic acid. The specific steps are as follows:
(1) Mix acetaldehyde with sodium hydroxide solution to produce sodium acetaldehyde.
(2) Hydrogen sulfuric acid gas is passed into the sodium acetaldehyde solution to control the pH between 8-9, and the reaction generates sodium mercaptoacetate.
(3) Acidify the sodium mercaptoacetate solution with sulfuric acid to obtain mercaptoacetic acid.
This method is a mature process and simple to operate, but the production process generates a large amount of wastewater and exhaust gas, which causes some pollution to the environment.
2. Acrylate method
The acrylate method is a relatively new method of manufacturing mercaptoacetic acid, and its reaction principle is to generate mercaptoacetic acid by reacting acrylate with hydrogen sulfide gas. The steps are as follows:
(1) Mix acrylate with sodium hydroxide solution to produce sodium acrylate.
(2) Hydrogen sulfide gas is passed into the sodium acrylate solution, and the reaction produces sodium mercaptoacetate.
(3) Acidify the sodium mercaptoacetate solution with sulfuric acid to obtain mercaptoacetic acid.
This method has the advantages of easy availability of raw materials, mild reaction conditions and environmental friendliness, but the flow and concentration of hydrogen sulfide gas need to be strictly controlled during the production process to ensure safe production.
3. Ethanol method
Ethanol method is a traditional method of manufacturing mercaptoacetic acid, and its reaction principle is to generate sodium mercaptoacetate through the reaction between ethanol and sodium hydrosulfide, and then acidification to get mercaptoacetic acid. The specific steps are as follows:
(1) Mix ethanol with sodium hydrosulfide solution and react to produce sodium mercaptoacetate and hydrogen.
(2) Acidify the sodium mercaptoacetate solution with sulfuric acid to obtain mercaptoacetic acid.
This method is simple to operate, but a large amount of exhaust gas and wastewater will be generated during the production process, while the reaction temperature and pH need to be strictly controlled to ensure the quality and yield of the product.
In short, there are various manufacturing methods for mercaptoacetic acid, and different methods have different advantages and disadvantages and applicable scope. When choosing the manufacturing method, you need to consider the cost of raw materials, environmental protection, safe production and other factors according to the actual situation, and choose the most suitable manufacturing method for you.
