Technology of preparing hdyroxy acetic acid

Abstract

The invention provides a process for preparing hydroxy-acetic acid which comprises, hydrolyzing hydroxyl acetonitrile aqueous solution and sulfuric acid to obtain hydroxy-acetic acid and the aqueous solution of the acidic salts of ammonium sulfate, then charging methanol into the aqueous solution for esterification, and distilling the mixture of methanol, water and hydroxy-acetic acid methyl ester, remaining the acidic salts of ammonium sulfate, then charging water into the distilled mixture for the hydrolysis of hydroxy-acetic acid methyl ester, separating methanol and obtaining crystallized hydroxy-acetic acid.

Description

technical field [0001] The invention relates to a process for preparing glycolic acid. Background technique [0002] The preparation method of the glycolic acid mentioned in the known literature has: the chloroacetic acid alkali hydrolysis of Japanese Patent Application No. 9-21684, concentration, after removing alkali metal chlorides, carry out electrodialysis with water dilution again; Kaiping 11-335319 mentions the use of ethylene glycol and nitrogen in the air to react in the gas phase with metal silver as a catalyst, and then through rectification and hydrolysis; U.S. Patent US4054601 and Chinese Patent Publication No. are the disclosed acidic hydrolysis of hydroxyacetonitrile CN1066650A After diluting with water, it can be extracted with butyl phosphate, trialkylphosphine hydroxide, etc. and prepared by back-extraction with water. [0003] Alkaline hydrolysis of chloroacetic acid produces glycolic acid and sodium chloride. This process requir...

AI Technical Summary

Problems solved by technology

[0003] Alkaline hydrolysis of chloroacetic acid produces glycolic acid and sodium chloride. This process requires concentration and esterification to remove most of the sodium chloride, and then ion membrane electrodialysis to remove residual sodium chloride. This process requires large investment and raw material costs. High and consumes a lot of electricity, and the final product still has chloride and sodium ions

[0004] Ethylene glycol reacts with air in the presence of a catalyst to form ethyl aldehyde, which is then mixed with air and catalyzed by an aluminum phosphate catalyst to obtain a mixture of glycolic acid, formaldehyde and alcohol, which is then rectified and hydrolyzed. The process is complex and the production high cost

[0005] Although the extraction process uses hydroxyacetonitrile, the extraction agent is expensive, requires a large investment, and has low production efficiency. The obtained product contains sulfate and residual extractant, which affects the quality of the product.