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Method for preparing and purifying hydroxyacetic acid by using hydroxyacetonitrile as raw material

A technology of hydroxyacetonitrile and hydroxyacetic acid, applied in the preparation of nitrile, chemical instruments and methods, ammonium sulfate and other directions, can solve the problems of acetone volatile loss, long reaction time, long esterification reaction time, etc., to achieve the reaction conditions Mild and easy to control, easy to operate, easy to recycle

Inactive Publication Date: 2013-01-30
EAST CHINA UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Usually, the object of liquid-liquid extraction treatment is the dilute solution of the separated substance. For the hydrolyzed solution containing high concentration of hydroxyacetonitrile, a large amount of pure water should be used for dissolving and diluting. The concentration of the aqueous phase containing glycolic acid obtained after back extraction is low, usually not high If the concentration is less than 10%, the energy consumption of the concentration process is high, the extraction agent is expensive and the loss is large, the equipment investment is large, and the operation is complicated. The product obtained by this method has a trace amount of extraction agent, which still needs to be further refined, otherwise the quality of the product will be affected.
After the hydroxyacetonitrile disclosed in Chinese Patent Publication No. CN1724504A is hydrolyzed under acidic conditions, methanol is added for esterification, and the mixture of methanol, water and glycolic acid is steamed, and then water is added for hydrolysis to separate glycolic acid. Obtain the very high product of purity, defect is that esterification reaction time is long, esterification rate is not high, causes process yield not high and energy consumption is big, production cost is high; Hydroxyacetonitrile disclosed in Chinese Patent No. CN1944379A is hydrolyzed in phosphoric acid, Then concentrate the crystallization to desalt and further desalt with acetone, and then concentrate the mixture of acetone, water and glycolic acid under reduced pressure. Using this method, the reaction time is long, the volatile loss of acetone is large, the environment is polluted, the cost is high, and it is easy to form in the distillation process. Peroxide, poor safety in large-scale industrial production

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] First add 48 grams of water and 120 grams of 98% concentrated sulfuric acid in a 1000ml four-necked flask equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, turn on the electric heating bowl to heat, and when the temperature rises to 120°C, stir Under the state of starting to slowly add dropwise 228g of hydroxyacetonitrile aqueous solution of 50% (mass ratio). The time for the dripping process of the material liquid and the reflux reaction process is 6 hours, that is, the solid is precipitated in the reaction liquid, the heating is stopped, and the material is cooled. The conversion rate of hydroxyacetonitrile was determined to be 98.73%. Use ammonia water to neutralize the excess residual sulfuric acid, remove a large amount of water under reduced pressure, and then use 657.1 grams of isopropanol solvent for alcohol analysis to desalt three times. The isopropanol solution of glycolic acid obtained at last contains 0.27% (mass ratio) of ...

Embodiment 2

[0033] First add 6.5 grams of water and 120 grams of 98% concentrated sulfuric acid in a 1000ml four-neck flask equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, turn on the electric heating bowl to heat, when the temperature rises to 120 ° C, stir Under the state of starting to slowly add dropwise 228g of hydroxyacetonitrile aqueous solution of 50% (mass ratio). The time for the dripping process of the material liquid and the reflux reaction process is 6 hours, that is, the solid is precipitated in the reaction liquid, the heating is stopped, and the material is cooled. The conversion rate of hydroxyacetonitrile was determined to be 98.70%. Use ammonia water to neutralize the excess residual sulfuric acid, remove a large amount of water under reduced pressure, and then use 585.0 g of absolute ethanol solvent for alcohol analysis, and desalt in three times. Containing 0.21% (mass ratio) of ammonium sulfate in the ethanol solution of glycolic acid ob...

Embodiment 3

[0035] In a 5000L jacketed glass-lined reactor equipped with a glass-lined stirring paddle of a reducer and a thermocouple, first add 378 kg of pure water and 884 kg of 98% concentrated sulfuric acid, and then slowly add 1606 kg of 50% ( mass ratio) of hydroxyacetonitrile aqueous solution. The reaction temperature is controlled between 114-123°C, and the hydrolysis reaction is carried out for 6h-8h. The density of the sampling analysis system is 1.28g / cm 3 (20°C). The reaction mixture was dehydrated by negative pressure in an industrial thin-film evaporator to obtain a paste-like mixture containing glycolic acid, ammonium sulfate and excess residual sulfuric acid. The conversion rate of hydroxyacetonitrile was determined to be 99.28%. Take 472.3 grams of the mixture, neutralize excess residual sulfuric acid with ammonia water, and then distill off the water under reduced pressure, then use 806.1 grams of methanol solvent for alcohol analysis, and desalting is carried out thr...

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Abstract

The invention relates to a method for preparing and purifying hydroxyacetic acid by using hydroxyacetonitrile as a raw material, which comprises the following steps of: adding sulfuric acid into aqueous solution of the hydroxyacetonitrile, and performing hydrolysis under a heating condition; adding aqueous ammonia into the solution to neutralize excessive residual sulfuric acid; removing most of water in the system; removing salt by using a low-carbon alcohol precipitation method; and removing low-carbon alcohol through reduced pressure distillation to obtain a hydroxyacetic acid product. The method has the advantages of simple production device, saved investment cost, low operation cost, high purity of the obtained hydroxyacetic acid product, full recycle of side products, no waste discharge and practicability of large-scale industrialized production.

Description

【Technical field】 [0001] The invention relates to the technical field of fine chemicals, in particular to a method for preparing and purifying glycolic acid using hydroxyacetonitrile as a raw material. 【Background technique】 [0002] Glycolic acid, also known as glycolic acid, glycolic acid, etc., is one of the fruit acids with simple molecular structure, and is also a very important fine chemical intermediate, which can be widely used in the surface cleaning of metal materials, dyeing aid of dyeing materials, Preparation of high-grade cosmetics, synthesis of biodegradable medical materials, production of polyglycolic acid polyester resin, etc. Mention in the published literature that the method for preparing glycolic acid has: the chloroacetic acid alkaline hydrolysis of Japanese Patent Publication No. 9-21684 communique, concentration, the electrodialysis method diluted with water after the alkali metal chloride is removed, by this method Chloride ion is difficult to remo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C59/06C07C51/08C07C51/42C01C1/24C01C1/242
Inventor 施云海张华云宁雷
Owner EAST CHINA UNIV OF SCI & TECH
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