oxalic acid

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Related to oxalic acid: oxalic acid poisoning

oxalic acid

(ŏksăl`ĭk) or

ethanedioic acid

(ĕth'āndīōĭk), HO2CCO2H, a colorless, crystalline organic carboxylic acid that melts at 189°C; with sublimation. Oxalic acid and oxalate salts are poisonous. Oxalic acid is found in many plants, e.g., sorrel and rhubarb, usually as its calcium or potassium salts. Oxalic acid is the only possible compound in which two carboxyl groupscarboxyl group
, in chemistry, functional group that consists of a carbon atom joined to an oxygen atom by a double bond and to a hydroxyl group, OH, by a single bond. Carboxylic acids are compounds whose molecules contain a carboxyl group that is joined to a hydrogen atom, an
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 are joined directly; for this reason oxalic acid is one of the strongest organic acids. Unlike other carboxylic acids (except formic acidformic acid
or methanoic acid
, HCO2H, a colorless, corrosive liquid with a sharp odor; it boils at 100.7°C; and solidifies at 8.4°C;. It has the lowest molecular weight and is the simplest of the carboxylic acids.
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), it is readily oxidized; this makes it useful as a reducing agent for photography, bleaching, and ink removal. Oxalic acid is usually prepared by heating sodium formate with sodium hydroxide to form sodium oxalate, which is converted to calcium oxalate and treated with sulfuric acid to obtain free oxalic acid.

Oxalic Acid


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.

oxalic acid

[äk′sal·ik ′as·əd]
(organic chemistry)
HOOCCOOH·2H2O Poisonous, transparent, colorless crystals melting at 187°C; soluble in water, alcohol, and ether; used as a chemical intermediate and a bleach, and in polishes and rust removers.

oxalic acid

a colourless poisonous crystalline dicarboxylic acid found in many plants: used as a bleach and a cleansing agent for metals. Formula: (COOH)2
References in periodicals archive ?
To use oxalic acid for bleaching and for removing rust and stains, water is added to the powder.
The analytical grade chemical reagents are pyruvic acid, oxalic acid, sodium citrate; oxaloacetate, sodium bicarbonate, and FDP were purchased from Sigma-Aldrich, Inc.
Oxalic acid converts into oxalate in the body, and it prevents the sedimentation of calcium in bones by sticking to it.
The Worldwide Oxalic Acid Industry Report - Forecast to 2020 is a professional and in-depth study on the current state of the oxalic acid industry.
Oxalate and its acid form oxalic acid are organic acids that come from three sources: the diet, fungus infections such as Aspergillus and Penicillium and possibly Candida, and also human metabolism.
More specifically, Friscic specializes in finding simple ways to chemically or mechanically accelerate the otherwise very slow natural weathering processes driven by organisms such as lichen, which employ simple organic molecules such as oxalic acid to extract and separate metals contained in minerals.
The purpose of adding oxalic acid solution with ethanol was to facilitate the solubility of rotenone during the extraction process.
John's son Edward filled a medicine bottle with oxalic acid to clean the metal bar counter and John drank it by mistake when he returned and dropped dead.
Veeken and Hamelers (1999) concluded that citric and oxalic acid have increased heavy metal extraction capacities (70% and 60%, respectively, for Cu; 90% and 70%, respectively, for Zn) at a mildly acidic pH of 3-4, as compared to HN[O.
The carboxylic acids used in this study were oxalic acid (OX), malic acid (MAL), citric acid (CIT), 4-hydroxybenzoic acid (HB), protocatechuic acid (PCH), 4-hydroxycinnamic acid (HC; also known as p-coumaric acid), and caffeic acid (CAF).
The fact that only the stalks are edible might have something to do with this because on no account should the leaves containing poisonous oxalic acid be eaten.
of a second alcohol ethoxylate nonionic surfactant; one or more further surfactants selected from amphoteric or zwitterionic surfactants, but which expressly exclude cationic surfactants; an organic solvent constituent; alkanolamine; and acid constituent which comprises a ternary acid system comprising each of sulfamic acid, formic acid and oxalic acid in a respective weight ratio of sulfamic acid:formic acid:oxalic acid of 1-8:1-5:1-3; optionally one or more further constituents which are directed to improving one or more aesthetic or functional features of the composition; and water.