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

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. Themethod 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...

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