A strong dicarboxylic acid occurring in many plants and vegetables. It is produced in the body by metabolism of glyoxylic acid or ascorbic acid. It is not metabolized but excreted in the urine. It is used as an analytical reagent and general reducing agent. Present in many plants and vegetables. Toxin from rhubarb, esp. the leaves but also present in the stems A strong dicarboxylic acid occurring in many plants and vegetables. It is produced in the body by metabolism of glyoxylic acid or ascorbic acid. It is not metabolized but excreted in the urine. It is used as an analytical reagent and general reducing agent. -- Pubchem; Bodily oxalic acid may also be synthesized via the metabolism of either glyoxylic acid or unused ascorbic acid (vitamin C), which is a serious health consideration for long term megadosers of vitamin C supplements. 80% of kidney stones are formed from calcium oxalate. Some Aspergillus species produce oxalic acid, which reacts with blood or tissue calcium to precipitate calcium oxalate. There is some preliminary evidence that the administration of probiotics can affect oxalic acid excretion rates (and presumably oxalic acid levels as well.) -- Wikipedia; Oxalate, the conjugate base of oxalic acid, is an excellent ligand for metal ions. It usually binds as a bidentate ligand forming a 5-membered MO2C2 ring. An illustrative complex is potassium ferrioxalate, K3[Fe(C2O4)3]. The drug Oxaliplatin exhibits improved water solubility relative to older platinum-based drugs, avoiding the dose-limiting side-effect of nephrotoxicity. Oxalic acid and oxalates can be oxidized by permanganate in an autocatalytic reaction.; Oxalic acid (IUPAC name: ethanedioic acid, formula H2C2O4) is a dicarboxylic acid with structure (HOOC)-(COOH). Because of the joining of two carboxyl groups, this is one of the strongest organic acids. It is also a reducing agent. The anions of oxalic acid as well as its salts and esters are known as oxalates. -- Wikipedia; Oxalic acid is an important reagent in lanthanide chemistry. Hydrated lanthanide oxalates form readily in strongly acid solution in a densely crystalline easily filtered form, largely free from contamination by non-lanthanide elements. Lanthanide oxalates figure importantly in commercial processing of lanthanides, and are used to recover lanthanides from solution after separation. Upon ignition, lanthanide oxalates are converted to the oxides, which are the most common form in which the lanthanides are marketed.; Oxalic acid is the chemical compound with the formula H2C2O4. This dicarboxylic acid is better described with the formula HOOCCOOH. It is a relatively strong organic acid, being about 3,000 times as strong as acetic acid. The di-anion, known as oxalate, is also a reducing agent as well as a ligand in coordination chemistry. Many metal ions form insoluble precipitates with oxalate, a prominent example being calcium oxalate, which is the primary constituent of the most common kind of kidney stones.

Oxalic acid is a dicarboxylic acid. It is a colorless crystalline solid that dissolves in water to give colorless, acidic solutions. In terms of acid strength, it is much stronger than acetic acid. Oxalic acid, because of its di-acid structure can also act as a chelating agent for metal cations. About 25% of produced oxalic acid is used as a mordant in dyeing processes. It is also used in bleaches, especially for pulpwood. Oxalic acid's main applications include cleaning (it is also found in baking powder) or bleaching, especially for the removal of rust. Oxalic acid is found in a number of common foods with members of the spinach family being particularly high in oxalates. Beat leaves, parsley, chives and cassava are quite rich in oxalate. Rhubarb leaves contain about 0.5% oxalic acid and jack-in-the-pulpit (Arisaema triphyllum) contains calcium oxalate crystals. Bacteria naturally produce oxalates from the oxidation of carbohydrates. At least two pathways exist for the enzyme-mediated formation of oxalate in humans. In one pathway, oxaloacetate (part of the citric acid cycle) can be hydrolyzed to oxalate and acetic acid by the enzyme oxaloacetase. Oxalic acid can also be generated from the dehydrogenation of glycolic acid, which is produced by the metabolism of ethylene glycol. Oxalate is a competitive inhibitor of lactate dehydrogenase (LDH). LDH catalyses the conversion of pyruvate to lactic acid oxidizing the coenzyme NADH to NAD+ and H+ concurrently. As cancer cells preferentially use aerobic glycolysis, inhibition of LDH has been shown to inhibit tumor formation and growth. However, oxalic acid is not particularly safe and is considered a mild toxin. In particular, it is a well-known uremic toxin. In humans, ingested oxalic acid has an oral lowest-published-lethal-dose of 600 mg/kg. It has been reported that the lethal oral dose is 15 to 30 grams. The toxicity of oxalic acid is due to kidney failure caused by precipitation of solid calcium oxalate, the main component of kidney stones. Oxalic acid can also cause joint pain due to the formation of similar precipitates in the joints.