METHOD FOR SEPARATING GLYCOLIC ACID FROM MIXED GLYOXAL DISPROPORTIONATION PRODUCTS Russian patent published in 2017 - IPC C07C59/06 C07C51/02 C07C51/487 

FIELD: chemistry.

SUBSTANCE: invention relates to chemical industry and specifically to a method for separating glycolic acid which is widely used in cosmetics, oil-and-gas, leather industries and is also used in the synthesis of biodegradable polymers and copolymers, for example, it is the precursor for producing polyglycolide andpoly lactide-co-glycolide. Method for separating glycolic acid from the mixed glyoxal disproportionation products comprises treating of this mixture with compounds of Ca (An) ₂ , where An = Cl, Br, I, NO₃, CH₃COO, using them as solutions or solids calculated as 0.45-0.5 mol Ca (An) ₂ per each mole of used glyoxal for precipitation formation of partially soluble calcium glycolate which is filtered, dried and the calcium salt of glycolic acid content in this residue is determined by the number of calcium cations using complexometric titration or atomic emission spectroscopy, afterwards this residue is added in the solid form to the ethanedioic acid solution or the ethanedioic acid solution is added to the aqueous suspension of this residue while stirring followed by filtration and concentration of the filtrate, wherein the ethanedioic acid in both cases is used at a rate of 0,9-10 mole per each mole of calcium glycolate containted in the mixture, its solution temperature is 20-80°C.

EFFECT: invention enables production of the end product with high output and purity.

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