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A kind of preparation method of mercaptoacetic acid

A technology of mercaptoacetic acid and sodium monochloroacetate, applied in mercaptan preparation, organic chemistry and other directions, can solve problems such as increased production process, increased production cost, complicated production process, etc., and achieves low cost of raw materials, low consumption of reagents, and utilization of sulfur. high rate effect

Inactive Publication Date: 2016-12-07
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 discloses a preparation method of mercaptoacetic acid, which comprises the following steps: 1) In a reactor, add monochloroacetic acid, sodium monochloroacetate and carbon disulfide, stir, add alkali solution dropwise, after the reaction is completed, separate the oil phase and the water phase ;2) After separation of the oil phase mixture, unreacted carbon disulfide is recovered and recycled, and the residual mixture is acidified into a weak acid solution, which is extracted by adding an organic solvent for 2 to 3 times, the organic phase is combined, washed with saline solution and water, and the oil phase is separated and the water phase; 3) The separated oil phase is distilled to recover the organic solvent, and the residue is thioglycolic acid. Carbon disulfide reacts with alkali to generate mercapto groups, and then reacts with sodium monochloroacetate to generate sodium thioglycolate. Adding an appropriate amount of acid, organic solvent, and alkali solution, the cost of raw materials is low and the consumption of reagents is low; excessive carbon disulfide is recovered and recycled for use. High efficiency, clean production process; mild reaction conditions, short reaction time, no need for high temperature and high pressure, low equipment investment costs.

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 salt. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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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