METHOD FOR SEPARATION OF GLYOXALIC ACID FROM PRODUCTS OF GLYOXAL OXIDATION Russian patent published in 2016 - IPC C07C59/153 C07C51/41 C07C51/43 C07C51/42 

FIELD: chemistry.

SUBSTANCE: invention relates to chemical industry, in particular to method for separation of glyoxalic acid (GA), which is widely applied in organic synthesis, for example is initial product for obtaining vanillin, allantoin and biodegradable polymers. Method for extraction of glyoxalic acid from mixture of glyoxal oxidation products, which contain oxalic and glyoxalic acids, includes processing of said mixture with oxide, hydroxide or carbonate of calcium counted as 0.45-0.5 mole of oxide, hydroxide or carbonate of calcium per each mole of protons, contained in this mixture and determined by titration for total acidity or in control of medium pH to values 4-7 to form mixture of poorly soluble sediments of calcium salts of glyoxalic and oxalic acids, with the following filtration, drying and determination of content of calcium salt of glyoxalic acid in this mixture by quantity of calcium cations by means complexometric titration or atomic-emission spectroscopy. After that, addition of mixture to solution of oxalic acid at 20-80°C is realised with further mixing and the following filtration and concentration of filtrate, with oxalic acid being taken in quantity 0.9-1.0 mole per each mole of calcium glyoxalate, contained in mixture.

EFFECT: method makes it possible to separate glyoxalic acid from products of glyoxal oxidation through mixture of calcium salts of glyoxalic and oxalic acids without application of specific equipment and ion-exchange resins.

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