Oxalic acid
Systematic name	ethanedioic acid
Chemical formula	C2H2O4 (anhydrous) C2H2O4.2H2O (dihydrate)
SMILES	OC(=O)C(O)=O
Molecular mass	90.03 g/mol (anhydrous) 126.07 g/mol (dihydrate)
Appearance	white crystals
CAS number	[144-62-7] (anhydrous) [6153-56-6] (dihydrate)
Properties
Density	1.90 g/cm3 (anhydrous) 1.653 g/cm3 (dihydrate)
Solubility in water	9.5 g / 100 ml (15°C) 14.3 g / 100 ml (25°C?) 120 g / 100 ml (100°C)
Solubility in Ethanol	23.7 g / 100 ml (15°C) (dihydrate)
Solubility in Diethyl ether	1.37 g / 100 ml (15°C) (dihydrate)
Sublimation point	157 °C
Decomposition	189.5 °C
pKa 25°C	1.23 (pK1) 4.19 (pK2)
Crystal Structure	rhombic (anhydrous) monoclinic (dihydrate)
Hazards
LD50	7.5 g/kg
NFPA 704	Image File history File links Oxalic_acid. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. ... The molecular mass (abbreviated MM) of a substance, called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... Density (symbol: ρ - Greek: rho) is a measure of mass per unit of volume. ... It has been suggested that this article or section be merged with Solution. ... Water (H2O, HOH) is the most abundant molecule on Earth, composing 70-75% of the Earths surface as liquid and solid state in addition to being found in the atmosphere as a vapor. ... It has been suggested that this article or section be merged with Solution. ... This article is about the chemical compound. ... It has been suggested that this article or section be merged with Solution. ... Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic smell. ... Sublimation of an element or substance is a conversion between the solid and the gaseous phases of matter, with no intermediate liquid stage. ... Rotting fruit Decomposition is a phenomenon common in the sciences of biology and chemistry. ... In chemistry and biochemistry, the acid dissociation constant, the acidity constant, or the acid-ionization constant (Ka) is a specific type of equilibrium constant that indicates the extent of dissociation of hydrogen ions from an acid. ... Rose des Sables (Sand Rose), formed of gypsum crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... This shape is a Rhombus In geometry, a rhombus (also known as a rhomb) is a parallelogram in which all of the sides are of equal length. ... In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ... An LD50 test being administered In toxicology, the LD50 or colloquially semilethal dose of a particular substance is a measure of how much constitutes a lethal dose. ... NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ... Image File history File links NFPA_704. ... 1 3 0
Flash point	166 °C
Related compounds
Related compounds	oxalyl chloride disodium oxalate calcium oxalate phenyl oxalate ester
Disclaimer and references

Oxalic acid (IUPAC name: ethanedioic acid, formula C₂H₂O₄) 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. The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture with air. ... Safety (MSDS) data for oxalyl chloride General Synonyms: ethanedioyl chloride, oxalic acid chloride, oxalic acid dichloride, oxalyl dichloride, oxalic dichloride, oxaloyl chloride Molecular formula: C2Cl2O2 CAS No: 79-37-8 EINECS No: 201-200-2 Physical data Appearance: colourless liquid Melting point: - 9 C Boiling point: 63 - 64 C Vapour... Disodium oxalate is a sodium salt of oxalic acid. ... Calcium oxalate is a chemical compound that forms needle-shaped crystals. ... Phenyl oxalate ester, also known as Cyalume, is a liquid ester whos hydrolysis products are responsible for the luminescence in a glowstick. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A dicarboxylic acid is an organic compound where each molecule contains two carboxylic acid functional groups, often written -COOH. Dicarboxylic acids can be used to prepare copolymers such as nylon and polyethylene terephthalate. ... In chemistry, a carboxyl group is a functional group consisting of a carbon atom doubly bonded to an oxygen atom and single-bonded to a hydroxyl (-OH) group, typically written as -COOH: where R is a hydrogen or an organic group. ... In chemistry, a carboxyl group is a functional group consisting of a carbon atom doubly bonded to an oxygen atom and single-bonded to a hydroxyl (-OH) group, typically written as -COOH: where R is a hydrogen or an organic group. ... An organic acid is an organic compound that is an acid. ... A reducing agent is the element or a compound in a redox (reduction-oxidation) reaction (see electrochemistry) that reduces another species. ... An anion is an ion with negative charge. ... A magnified crystal of a salt (halite/sodium chloride) In chemistry, a salt is any ionic compound composed of positively charged cations and negatively charged anions so that the product is neutral and without a net charge. ... General formula of a carboxylate ester. ... The oxalate (also ethanedioate) ion is (COO)22− (oxalic acid minus two hydrogen ions). ...

Biological hazards

Main article: oxalate poisoning

Oxalic acid and oxalates are mild nephrotoxic acids that are abundantly present in many plants, most notably fat hen (lamb's quarters), rhubarb and sorrel. Oxalic acid irritates the lining of the gut when consumed, and can prove fatal in large doses. The LD50 for pure oxalic acid is predicted to be about 378 mg/kg body weight, or about 22 g for a 60 kg human. Oxalic acid can also be present in the body due to the consumption of another toxin, ethylene glycol (generally known as automobile antifreeze), because over time, the body metabolizes ethylene glycol partially into oxalic acid. Estimated fatal dose is 5 to 15 grams. Oxalate poisoning in animals generally occurs when quantities of oxalate-containing plants are grazed by livestock that are not accustomed to eating the plants. ... Nephrotoxicity is a poisonous effect of some substances, both toxins and medication, on the kidney. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants... Binomial name Chenopodium album L. Fat Hen (Chenopodium album), also called white goosefoot, lambs quarters, lambsquarters, or pigweed, is a fast-growing, upright, weedy annual species of goosefoot, very common in temperate regions, growing almost everywhere in soils rich in nitrogen, especially on wasteland. ... Species See text Rhubarb is a perennial plant that grows from thick short rhizomes, comprising the genus Rheum. ... Binomial name Rumex acetosa The common sorrel, or spinach dock, is a perennial herb, which grows abundantly in meadows in most parts of Europe and is cultivated as a leaf vegetable. ... For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... An LD50 test being administered In toxicology, the LD50 or colloquially semilethal dose of a particular substance is a measure of how much constitutes a lethal dose. ... The milligram (symbol mg) is an SI unit of mass. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ... Body weight is simply the weight of anything, including humans. ... BIC pen cap, about 1 gram. ... Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin for wise man or knowing man) under the family Hominidae (the great apes). ... Ethylene glycol (monoethylene glycol (MEG), IUPAC name: ethane-1,2-diol) is an alcohol with two -OH groups (a diol), a chemical compound widely used as an automotive antifreeze. ...

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. ^[1] Some Aspergillus species produce oxalic acid, which reacts with blood or tissue calcium to precipitate calcium oxalate.^[2] There is some preliminary evidence that the administration of probiotics can affect oxalic acid excretion rates ^[3] (and presumably oxalic acid levels as well.) This article deals with the molecular aspects of ascorbic acid. ... 3D representation of vitamin C Chemical structure of vitamin C Vitamin C is a water-soluble nutrient and vitamin essential for life and for maintaining optimal health. ... Kidney stones are solid accretions (crystals) of dissolved minerals in urine found inside the kidneys or ureters. ... Species Aspergillus caesiellus Aspergillus candidus Aspergillus carneus Aspergillus clavatus Aspergillus deflectus Aspergillus flavus Aspergillus fumigatus Aspergillus glaucus Aspergillus nidulans Aspergillus niger Aspergillus ochraceus Aspergillus oryzae Aspergillus parasiticus Aspergillus penicilloides Aspergillus restrictus Aspergillus sojae Aspergillus sydowi Aspergillus terreus Aspergillus ustus Aspergillus versicolor Aspergillus is a genus of around 200 fungi (moulds...

Action of poisoning

Oxalic acid also combines with metals such as calcium, iron, sodium, magnesium, and potassium in the body to form oxalate crystals which precipitate and irritate the gut and kidneys. The calcium oxalate preciptate (better known as kidney stones) obstruct the kidney tubules. Because it binds vital nutrients such as calcium, long-term consumption of foods high in oxalic acid can lead to nutrient deficiencies. Healthy individuals can safely consume such foods in moderation, but those with kidney disorders, gout, rheumatoid arthritis, or certain forms of chronic vulvar pain (vulvodynia) are typically advised to avoid foods high in oxalic acid or oxalates. Conversely, calcium supplements taken along with foods high in oxalic acid can cause oxalic acid to precipitate in the gut and drastically reduce the levels of oxalate absorbed by the body (by 97% in some cases.)^{[4] [5]} General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Atomic mass 39. ... Human kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... Bladder stone redirects here. ... Nutrients and the body A nutrient is any element or compound necessary for or contributing to an organisms metabolism, growth, or other functioning. ... // Nutrients and the body A nutrient is any element or compound necessary for or contributing to an organisms metabolism, growth, or other functioning. ... Human kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. ... Rheumatoid arthritis (RA) is traditionally considered a chronic, inflammatory autoimmune disorder that causes the immune system to attack the joints. ... The term vulvodynia is used to describe pain in the vulva, often severe, of unknown cause. ... Oxalates are hard lumps of salt crystals formed when Oxalic Acid combines with calcium, iron, sodium, magnesium, or potassium. ...

Oxalic acid containing foods

The root and leaves of rhubarb contain dangerously high concentrations of oxalic acid. Species See text Rhubarb is a perennial plant that grows from thick short rhizomes, comprising the genus Rheum. ...

Foods that are edible, but still contain significant concentrations of oxalic acid include - in decreasing order - buckwheat, star fruit (carambola), black pepper, parsley, poppy seed, rhubarb stalks, amaranth, spinach, chard, beets, cocoa, chocolate, most nuts, most berries, and beans. The gritty feel one gets in the mouth when drinking milk with rhubarb desserts is caused by precipitation of calcium oxalate. Thus even dilute amounts of oxalic acid can readily "crack" the casein found in various dairy products. Binomial name Fagopyrum esculentum Common Buckwheat (Fagopyrum esculentum) is a plant in the genus Fagopyrum (sometimes merged into genus Polygonum) in the family Polygonaceae. ... Binomial name Averrhoa carambola L. Carambolas still on the tree The carambola is a species of tree native to Sri Lanka and Bangladesh and is popular throughout Southeast Asia. ... Binomial name Piper nigrum L. Black pepper (Piper nigrum) is a flowering vine in the family Piperaceae, cultivated for its fruit, which is usually dried and used as a spice and seasoning. ... Species Percentages are relative to US RDI values for adults. ... Poppy at High Wood Cemetery, France. ... Species See text Rhubarb is a perennial plant that grows from thick short rhizomes, comprising the genus Rheum. ... Species See text. ... Binomial name Spinacia oleracea L. Percentages are relative to US RDI values for adults. ... Trinomial name Beta vulgaris var. ... Binomial name Beta vulgaris L. The beet (Beta vulgaris) is a flowering plant in the family Amaranthaceae, native to the coasts of western and southern Europe, from southern Sweden and the British Isles south to the Mediterranean Sea. ... Cocoa beans in a cacao pod Cocoa is the dried and partially fermented fatty seed of the cacao tree from which chocolate is made. ... Chocolate most commonly comes in dark, milk, and white varieties, with cocoa solids contributing to the brown coloration. ... Hazelnuts from the Common Hazel Chestnut Carya ovata nut anatomy A nut is a seed of a plant. ... Several types of berries from the market, but none of these are true berries. ... Green beans Bean is a common name for large plant seeds of several genera of Fabaceae (formerly Leguminosae) used for food or feed. ... A glass of cows milk Milk is the nutrient fluid produced by the mammary glands of female mammals (including monotremes). ... Calcium oxalate is a chemical compound that forms needle-shaped crystals. ... Casein is the predominant phosphoprotein found in fresh milk. ...

Leaves of the tea plant (Camellia sinensis) are known to contain among the greatest measured concentrations of oxalic acid relative to other plants. However the infusion beverage typically contains only low to moderate amounts of oxalic acid per serving, due to the small mass of leaves used for brewing. Tea leaves in a Chinese gaiwan. ... Binomial name Camellia sinensis (L.) Kuntze Camellia sinensis is one of the two major varieties or strains of the tea plant, the plant species whose leaves and leaf buds are used to produce tea (The other being Camellia Assamica). ...

Research is being done on methods to safely reduce oxalate in food. ^[6]

Uses

• In household chemical products such as Bar Keeper's Friend, some bleaches, and rustproofing treatments.
• In wood restorers where the acid dissolves away a layer of dry surface wood to expose fresh material underneath.
• As a mordant in dyeing processes.
• Vaporized oxalic acid is used by some beekeepers as an insecticide against the parasitic Varroa mite.

Household chemicals are chemicals that are commonly found and used in and around the average household. ... Bar Keepers Friend is a powdered household cleaner sold for use particularly on metals, but also on other household items. ... In chemistry, to bleach something generally means to whiten it or oxidize it. ... A blacksmith removing rust with sand prior to welding Rust damage in automobiles can create hidden dangers. ... Look up Mordant on Wiktionary, the free dictionary A mordant is a substance used to set dyes. ... Beekeeping (or apiculture) is the maintenance of one or more hives of honeybees. ... A insecticide is a pesticide used against insects in all development forms. ... Binomial name Varroa destructor Anderson & Trueman, 2000 Varroa destructor is an external parasitic mite that attacks honey bees Apis cerana and Apis mellifera, the bumblebee Bombus pennsylvanicus, the scarab beetle Palpada vinetorum and the flower-fly Phanaeus vindex. ...

Tests for oxalic acid

Titration with potassium permanganate can reveal the presence of oxalic acid (as the acid is only a weak reductant, and needs an oxidant as strong as permanganate in order to react). However, this test will confuse ascorbate and oxalic acid, as will most tests based on reducing power: the solution is to run a second test for strong reductants using, for example, iodine. Titration setup: the titrant drops from the burette into the analyte solution in the flask. ... Potassium permanganate is the chemical compound KMnO4. ... Electrochemistry is the science of the reactions that can take place at the interface of an electronic conductor (the electrode, which can be a metal or a semiconductor including graphite) and an ionic conductor (the electrolyte). ... An oxidizing agent is a substance that oxidizes another substance in electrochemistry or redox chemical reactions in general. ... Ascorbic acid is an organic acid with antioxidant properties. ... General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ...

Preparation and Manufacture

Oxalic acid can be conveniently prepared in the laboratory by oxidizing sucrose using nitric acid as the oxidizer and a small amount of vanadium pentoxide as a catalyst.^[7] On a large scale, sodium oxalate is manufactured by absorbing carbon monoxide under pressure in hot sodium hydroxide.^[8] Sucrose (common name: table sugar, also called saccharose) is a disaccharide (glucose + fructose) with the molecular formula C12H22O11. ... The chemical compound nitric acid (HNO3), otherwise known as aqua fortis or spirit of nitre, is a colorless, corrosive liquid, a toxic acid which can cause severe burns. ... An oxidizing agent is a substance that oxidizes another substance in electrochemistry or redox chemical reactions in general. ... Vanadium(V) oxide (V2O5), commonly known as vanadium pentoxide, is the most important compound of vanadium. ... In chemistry, a catalyst (Greek: καταλύτης, catalytēs) is a substance that decreases the activation energy of a chemical reaction (see also catalysis) without itself being changed at the end of the chemical reaction. ... Carbon monoxide, chemical formula CO, is a colorless, odorless, tasteless, and highly toxic gas. ... Sodium hydroxide (NaOH), also known as lye (USA) or caustic soda, is a caustic metallic base. ...

External links

• International Chemical Safety Card 0529
• Oxalic acid description, properties, manufacture, and applications (ChemicalLand21.com)
• Oxalic acid MSDS (Mallinckrodt Baker, Inc.)
• Table: Oxalic acid content of selected vegetables (USDA)
• Query engine: Dr. Duke's Phytochemical and Ethnobotanical Databases (USDA ARS)
• About rhubarb poisoning (The Rhubarb Compendium)
• Article: 'Go Light on Oxalic Acid' (Dr. Mary Schrick's June 2004 newsletter)
• Medical Terminology Dictionary
• Low-Oxalate Diet (PDF)
• Link page to external chemical sources.

References

1. ^ Kidney stone disease by Coe FL, Evan A, Worcester E, on NIH website
2. ^ Aspects of oxalosis associated with aspergillosis in pathology specimens by Pabuccuoglu U. on NIH website
3. ^ Use of a probiotic to decrease enteric hyperoxaluria by Lieske JC, Goldfarb DS, De Simone C, Regnier C. on NIH website
4. ^ Gastrointestinal oxalic acid absorption in calcium-treated rats by Morozumi M, Hossain RZ, Yamakawa KI, Hokama S, Nishijima S, Oshiro Y, Uchida A, Sugaya K, Ogawa Y. on NIH website
5. ^ Milk and calcium prevent gastrointestinal absorption and urinary excretion of oxalate in rats by Hossain RZ, Ogawa Y, Morozumi M, Hokama S, Sugaya K. on NIH website
6. ^ Biodegradation of oxalic acid from spinach using cereal radicles by Betsche T, Fretzdorff B. on NIH website
7. ^ Practical Organic Chemistry by Julius B. Cohen, 1930 ed. preparation #42
8. ^ U.S. Patent 1602802