OXALIC ACID (a synonym
etandinovy acid) — dicarboxylic acid, BUT OS — C O IT, the lowest representative of a homologous series. At the person and animals Shch. to. it is formed as an end product of oxidizing deamination (see) amino acids of glycine (see). Genetically caused disturbance of exchange of glycine and its metabolite — glyoxylic acid (see), leading to accumulation in an organism of abnormal quantities Shch. to., the oxarod (see), shown an oksaluriya (see), symptoms of intersticial nephrite (see), an urolithiasis (see the Nephrolithiasis), a nephrocalcinosis is the reason of a hereditary disease (cm.) with the subsequent development of a renal failure and uraemia (see). Y. to. and its salts are used as anticoagulants and chemical reactants in gematol. practice and clinical diagnostic laboratories. They are applied also as bleaching agent in the textile and paper industry, to purification of metals of a rust, etc. Nek-ry connections Shch. to. are poisonous, napr, oxalonitrile [(CN)2, dinitrile oxalic to - you] works like cyanhydric acid (see), but is several times weaker.
Pier. the weight (weight) oxalic to - you 90, from water it crystallizes in the form of colourless crystals, * °pl 189,5 °, sublimating temperature 125 °. Y. to. it is hygroscopic, a rastvorima in water, alcohol, ether. It is strong to - that (see Acids and the bases) and an active reducer. Salts and ethers Shch. to. are called oxalates. Oxalates of alkaline and heavy metals are almost insoluble, the method of quantitative definition Shch is based on this their property. to. Potassium permanganate in acid solution easily oxidizes Shch. to. to C02 carbon dioxide and water, .chto it is used in titrimet-r and ches the lump anat to Iza (with m).
Y. to. receive bystry heating of sodium formiate to temperature St. 350 °, and also saponification of oxalonitrile and other ways. This to - that is formed at fermentation of carbohydrates by nek-ry lowest fungi (Aspergillus niger, etc.) and bacteria.
Oxalates contain in many plants, their concentration in a sorrel, an oxalis, nek-ry seaweed, ferns, lichens is especially high.
Formed in a human body or an animal Shch. to. is not exposed to further transformations and together with Shch. to. food (exogenous Shch. to.) it is allocated with urine (see) in the form of calcium oxalate. Y. to., contained in food, it is partially soaked up in intestines, partially collapses its microflora (partially by it it is synthesized). Daily allocation Shch. to. with urine of the healthy adult makes 10 — 20 mg, in urine of the child of the first year of life contents Shch. to. (except for the first month of life) is slightly higher, than at adults. Concentration Shch. to. in whole blood of the adult on average makes 2 — 4 mg! 100 ml, in blood serum — 0,2 mg / 100 ml.
One of the most often found forms of urinary stones (see) are the oxalate (oxalic) stones consisting of Sas204-H20 hydro-calcium oxalate and Sas204-2H20 dihydrocalcium oxalate. At high concentration Shch. to. in urine oxalates can drop out in a deposit in the form of free crystals — uric sand. Calcium oxalates in a small amount are emitted with bile.
Bibliography: Berezov T. T. and To
rovkin B. F. Biological chemistry, page 511, M., 1982; Karrer P. A course of organic chemistry, the lane with it., JI., 1960.
N. F. Tolkachevskaya.