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Method for producing methyl thioglycolate based on sodium hydrosulfide method

A technology of methyl thioglycolic acid and thioglycolic acid, applied in the field of producing methyl thioglycolic acid, can solve the problems of long reaction time, high cost, lower yield of finished products, etc. The effect of improving the quality and enhancing the activity of molecules

Active Publication Date: 2021-03-23
山东沾化金嘉利化工科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

There are many problems such as low yield, long reaction time, equipment corrosion and serious environmental pollution.
Chloride catalysts are also used to catalyze the synthesis of methyl thioglycolate. These methods also have the disadvantages of low yield and high cost, which greatly limit their wide application.
[0003] Chinese patent CN102477006A discloses a method for synthesizing methyl thioglycolate. The method uses methyl chloroacetate as a raw material and is synthesized through steps such as salt formation, acidification, extraction, and separation. This process has the disadvantages of cumbersome process and high energy consumption.
[0004] Chinese patent CN101580485A discloses a method for producing methyl thioglycolate. The method uses 70-96% thioglycolic acid and methanol as raw materials, and uses p-toluenesulfonic acid as an activator to carry out esterification reaction. Although the patent reduces the main raw material The purity of thioglycolic acid, but thioglycolic acid is extremely unstable and prone to polymerization when the content is greater than 70%, thus reducing the yield of finished products
This brings certain difficulty to the preparation of methyl thioglycolate

Method used

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  • Method for producing methyl thioglycolate based on sodium hydrosulfide method
  • Method for producing methyl thioglycolate based on sodium hydrosulfide method
  • Method for producing methyl thioglycolate based on sodium hydrosulfide method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] (1) 1000mL of thioglycolic acid acidification solution synthesized by the sodium hydrosulfide method is added in portions to a distillation flask, concentrated by decompression distillation and dehydration, and centrifuged to separate NaCl solid to obtain 200 g of distillation concentrated solution; the concentration of thioglycolic acid is 50wt.%.

[0043] (2) Slowly add CaCl to the distillation concentrate 2 100g, CaCl 2 Form the molten salt hydrate with the water in the distilled concentrate, at this moment, there will be solid NaCl to separate out constantly, after separating out the NaCl solid, merge with the NaCl solid of the centrifugal separation of step (1) gained to form solid salt; Then use 2 times the mass of methanol to wash the solid salt twice, the methanol deesterification reaction process after washing the solid salt, and the washed solid salt is used as a by-product after drying.

[0044](3) Add 0.3 g of p-toluenesulfonic acid and 103 g of methanol ...

Embodiment 2

[0051] (1) 1000mL of thioglycolic acid acidification solution synthesized by the sodium hydrosulfide method is added in portions to a distillation flask, concentrated by decompression distillation and dehydration, and centrifuged to separate the NaCl solid to obtain 150 g of distillation concentrated solution; the concentration of thioglycolic acid is 65wt.%.

[0052] (2) Slowly add the distillation concentrate of step (1) to the lower aqueous phase of Example 1, where the CaCl 2 Hydrate is molten salt hydrate. At this time, there will be solid NaCl precipitated continuously. After the separated NaCl solid is separated, it will be combined with the centrifuged NaCl solid obtained in step (1) to form a solid salt; then use 2 times the mass of methanol The solid salt is washed 3 times, and the methanol deesterification reaction process after washing the solid salt is used as a by-product after the washed solid salt is dried.

[0053] At the same time, add a small amount of CaCl...

Embodiment 3

[0062] (1) 700mL of thioglycolic acid acidification solution synthesized by the sodium hydrosulfide method is added in portions to a distillation flask, concentrated by decompression distillation and dehydration, and centrifuged to separate NaCl solid to obtain distillation concentrated solution 100g; the concentration of thioglycolic acid is 69.5 wt.%.

[0063] (2) Slowly add the distillation concentrated solution of step (1) to the lower layer aqueous phase concentrated solution of Example 2, wherein the CaCl 2 Hydrate is molten salt hydrate. At this time, there will be solid NaCl precipitated continuously. After the separated NaCl solid is separated, it will be combined with the centrifuged NaCl solid obtained in step (1) to form a solid salt; then use 2 times the mass of methanol The solid salt is washed twice, and the methanol deesterification reaction process after washing the solid salt is used as a by-product after the washed solid salt is dried.

[0064] At the same ...

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Abstract

The invention relates to a method for producing methyl thioglycolate based on a sodium hydrosulfide method, which belongs to the technical field of organic synthesis. The method comprises the step ofdistilling and concentrating thioglycolic acid acidified liquid, and adding CaCl2 to obtain distilled and concentrated liquid containing molten salt hydrate, an esterification reaction step in which the molten salt hydrate is used as a reaction medium, and the step of settling and layering to obtain methyl thioglycolate. The separation of thioglycolic acid, the treatment of the extraction tail wastewater and the esterification reaction are integrated, the production process is greatly simplified, the water and the solid salt can be effectively separated, the content of organic matters in the water and the solid salt is low, the separated water can be recycled, and the solid salt can also be used as a byproduct. The side reaction in the production process of the methyl thioglycolate is greatly reduced, the discharge of wastewater and the dosage of a catalyst are reduced, and the resource recycling is realized.

Description

technical field [0001] The invention relates to a method for producing methyl thioglycolate based on a sodium hydrosulfide method, belonging to the technical field of organic synthesis. Background technique [0002] Methyl thioglycolate, also known as methyl thioglycolate, is an intermediate widely used in the synthesis of medicine, pesticide, food and tobacco flavors. At present, the production synthesis method of methyl thioglycolate mainly uses thioglycolic acid and methanol as raw materials, and H 2 SO 4 , solid superacid, etc. as catalysts for esterification synthesis. There are multiple problems such as low yield, long reaction time, equipment corrosion and serious environmental pollution. Chloride catalysts are also used to catalyze the synthesis of methyl thioglycolate. These methods also have the defects of low yield and high cost, which greatly limit their wide application. [0003] Chinese patent CN102477006A discloses a method for synthesizing methyl thioglyc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C323/52C07C319/12C07C319/28C01D3/04C01D3/14C01D3/16C02F1/04
CPCC07C319/12C07C319/28C01D3/04C01D3/14C01D3/16C02F1/048C07C323/52Y02P20/584
Inventor 王景华于龙张广俊崔洪友
Owner 山东沾化金嘉利化工科技有限公司
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