oxalic acid(redirected from Dimethyl oxalate)
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HOOC—COOH, the simplest dibasic carboxylic acid. A colorless crystalline compound, oxalic acid has a melting point of 189.5°C. Its solubility in water is 10 g per 100 g H2O at 20°C and 120 g at 100°C. Oxalic acid is poorly soluble in alcohol and ether and is insoluble in benzene and chloroform. It is a relatively strong acid (K125 = 3.6 × 10–2). It forms the hydrate C2H2O42H2O (melting point, 101.5°C), as well as acid and neutral salts (oxalates), esters, amides, and other derivatives.
Salts of oxalic acid are found in plants—for example, its acid potassium salt is found in sorrel (genus Oxalis, hence the name). The acid forms in tissues as a metabolic product and, together with the oxalic acid in food, is excreted with urine as potassium oxalate. Oxalates participate in the formation of stones in the kidneys and urinary bladder in cases of disorders of mineral metabolism. Oxalic acid is formed in oxalic acid fermentation.
Oxalic acid was first synthesized in 1842 by F. Wöhler from cyanogen. It is produced industrially by the pyrolysis of sodium formate, HCOONa. It is used as mordant in cloth printing; it is also used in the production of dyes and inks, as a bleaching agent, and as a precipitating agent for rare earths.