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Method for preparing mercaptoacetic acid

A technology of mercaptoacetic acid and sodium monochloroacetate, which is applied in the fields of mercaptan preparation and organic chemistry, can solve the problems of high production cost, equipment corrosion, and many steps, and meet the requirements of low equipment investment and operating costs and equipment corrosion resistance The effect of low, mild reaction conditions

Inactive Publication Date: 2014-12-10
湖南立新环保科技发展有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the production process is relatively complicated, and non-ferrous metal zinc needs to be used as a reducing agent, which increases the production cost. In addition, hydrolysis requires a large amount of inorganic acid, which seriously corrodes the equipment; the sodium disulfide method, Chinese patent CN101921217A, uses sodium disulfide and chloroacetic acid React to synthesize sodium 2,2'-dithiodiacetate, and finally reduce it with sodium hydrosulfide and sodium sulfite solution to obtain its intermediate product, but sodium disulfide still needs to be prepared by reacting sodium sulfide with sulfur, and its production process increases. It needs to be reduced with sodium hydrosulfide and sodium sulfite, the production cost is high, the process is complicated, there are many steps, side reactions increase, and the purity is difficult to guarantee

Method used

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preparation example Construction

[0018] A preparation method for thioglycolic acid, comprising the steps of:

[0019] 1) In a reactor equipped with a stirrer and a reflux condenser, add one or a combination of monochloroacetic acid, sodium monochloroacetate, carbon disulfide, stir, and dropwise add alkali solution to the reaction mixture to control the concentration of the mixture. The pH value is 8 to 9, the reaction temperature is 15°C to 46°C, and the reaction time is 1h to 8h. After the reaction is completed, cool to room temperature, stand for phase separation, separate the oil phase and the water phase, and recycle the collected water phase;

[0020] 2) Distill the oil phase mixture separated in step 1 to recover the unreacted carbon disulfide for recycling, then acidify the residual mixture after distillation with an appropriate amount of acid into a weak acid solution, add an appropriate amount of organic solvent to extract 2 ~3 times, combine the organic phases, wash with an appropriate amount of sat...

Embodiment 1

[0025] In a 1-liter four-neck flask equipped with a stirrer, a reflux condenser, and a dropping funnel, add 0.5 mol of sodium monochloroacetate and 302 ml of carbon disulfide, start the stirrer, and add 300 ml of 25% sodium carbonate solution dropwise to control the mixture solution. The pH value of the mixture is 8-9, and the reaction temperature is maintained at 44°C-46°C by heating. After 4 hours of reaction, the reaction mixture is cooled, allowed to stand to separate layers, and the carbon disulfide oil phase is separated. The separated oil phase mixture is distilled to recover unreacted carbon disulfide, and the residual mixture after distilling and recovering carbon disulfide is added dropwise with 20% sulfuric acid under stirring to make the pH value 2 to 3. After the mixture is cooled, add 200ml of petroleum ether, after stirring and mixing well, let stand to separate the layers, separate the petroleum ether layer, then extract the target product in the mixture with 2×...

Embodiment 2

[0027] In a 1-liter four-necked flask equipped with a stirrer, a reflux condenser, and a dropping funnel, add 0.5 mol of monochloroacetic acid and 181 ml of carbon disulfide, start the stirrer, and add dropwise 300 ml of 25% sodium carbonate and 100 ml of 20% sodium hydroxide The mixture liquid composed of the solution, the pH value of the mixture solution is controlled to be 8-9, and the reaction temperature is maintained at 40°C-45°C by heating. After reacting for 6 hours, the reaction mixture is cooled, allowed to stand for stratification, and the carbon disulfide oil phase is separated. The separated oil phase mixture is distilled to recover unreacted carbon disulfide, and the residual mixture after distilling and recovering carbon disulfide is added dropwise with 20% hydrochloric acid under stirring to make the pH value 2 to 3. After the mixture is cooled, add 200ml of diethyl ether , after stirring and mixing well, let stand to separate the layers, separate the petroleum ...

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Abstract

The invention relates to a method for preparing mercaptoacetic acid. The method comprises the following steps: (1) adding monochloro acetic acid, sodium chloroacetate and carbon disulfide into a reactor, stirring, dripping an alkali solution, and separating the oil phase from the water phase after the reaction is completed; (2) recycling unreacted carbon disulfide from the separated oil phase mixture for circulation, acidifying the residual mixture into a weak acid solution, adding an organic solvent to extract for 2-3 times, combining organic phases, washing with a salt solution and water, and separating the oil phase and the water phase; and (3) distilling the separated oil phase, and recycling the organic solvent, thereby obtaining residues, that is, the mercaptoacetic acid. As carbon disulfide is adopted to react with alkali to generate sulfydryl, the sulfydryl is further reacted with sodium chloroacetate to generate sodium thioglycollate, and a proper amount of acids, organic solvent and alkali solution are added, the raw material cost is low, and a small amount of reagents are used; as the excessive carbon disulfide can be recycled and circulated, the utilization rate is high, and the method is a clean production process; the reaction conditions are gentle, the reaction time is short, no high temperature or high pressure is needed, and the equipment investment is low.

Description

technical field [0001] The invention relates to the technical field of fine chemicals, in particular to a preparation method of thioglycolic acid. Background technique [0002] Mercaptoacetic acid, English name: Mercapto acetic acid, alias name: thiol acetic acid, mercaptoacetic acid, ethanethiolic acid, hydrogen thioglycolic acid. Thioglycolic acid (chemical formula: C 2 h 4 o 2 S, formula weight: 92.12) Sulfur-containing organic compound, a colorless transparent liquid with a strong pungent odor. Miscible in ethanol, ether, soluble in common solvents. [0003] Thioglycolic acid is a very important fine chemical product, which is widely used in fur treatment, metal surface treatment, analytical chemistry, heat stabilizer for polymer materials, metal adsorbent and pharmaceutical synthesis intermediates. [0004] The preparation of mercaptoacetic acid is generally obtained by the nucleophilic reaction between a sulfur-containing nucleophile and a chloroacetic acid sa...

Claims

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Application Information

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IPC IPC(8): C07C319/02C07C323/52
Inventor 李立新曹敬曹津
Owner 湖南立新环保科技发展有限公司
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