Mesoxalic acid, also called oxomalonic acid or ketomalonic acid, is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with formula C₃H₂O₅ or HO−(C=O)₃−OH. Mesoxalic acid is both a

dicarboxylic acid In organic chemistry, a dicarboxylic acid is an organic compound containing two carboxyl groups (). The general molecular formula for dicarboxylic acids can be written as , where R can be aliphatic or aromatic.Boy Cornils, Peter Lappe "Dicarbox ...

and a ketonic acid. It readily loses two

proton A proton is a stable subatomic particle, symbol , Hydron (chemistry), H+, or 1H+ with a positive electric charge of +1 ''e'' (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an e ...

s to yield the

divalent In chemistry, the valence (US spelling) or valency (British spelling) of an atom is a measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Valence is generally understood to be the number of chemica ...

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

, called mesoxalate, oxomalonate, or ketomalonate. These terms are also used for

salts In chemistry, a salt or ionic compound is a chemical compound consisting of an assembly of positively charged ions ( cations) and negatively charged ions (anions), which results in a compound with no net electric charge (electrically neutral). ...

containing this anion, such as sodium mesoxalate, Na₂C₃O₅; and for

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

s containing the −C₃O₅− or −O−(C=O)₃−O− moiety, such as diethyl mesoxalate, (C₂H₅)₂C₃O₅. Mesoxalate is one of the oxocarbon anions, which (like

carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...

and

oxalate Oxalate (systematic IUPAC name: ethanedioate) is an anion with the chemical formula . This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (), and several esters such as ...

) consist solely of

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

and

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

. Mesoxalic acid readily absorbs and reacts with water to form a product commonly called "mesoxalic acid monohydrate", more properly dihydroxymalonic acid, HO−(C=O)−C(OH)₂−(C=O)−OH. In product catalogs and other contexts, the terms "mesoxalic acid", "oxomalonic acid" and so on often refer to this "hydrated" compound. In particular, the product traded as "sodium mesoxalate monohydrate" is almost always sodium dihydroxymalonate. Mesoxalic acid hydration equilibrium

Synthesis

Mesoxalic acid can be obtained synthetically by

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

alloxan Alloxan, sometimes referred to as alloxan monohydrate, is an organic compound with the formula . It is classified as a derivative of pyrimidine. The anhydrous derivative is also known, as well as a dimeric derivative. These are some of the earlie ...

with baryta water, by warming caffuric acidThe chemical structure of caffuric acid was given in Allen, W. F. (1932). The preparation and pyrolytic molecular rearrangment icof the 8-ethers of caffeine: And their conversion to 8-methyl and 8-ethylcaffeine. Ann Arbor, Mich.: Edwards Brothers. with lead acetate solution,Henry Enfield Roscoe (1888), ''A Treatise on Chemistry'', volume 3, part2 ''Organic Chemistry'', p. 161. D. Appleton and Co., New York or from glyceryl diacetate and concentrated

nitric acid Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...

in ice-cold water. The product can be obtained also by oxidation of tartronic acid or

glycerol Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pha ...

. Rosaria Ciriminna and Mario Pagliaro (2003), ''One-Pot Homogeneous and Heterogeneous Oxidation of Glycerol to Ketomalonic Acid Mediated by TEMPO''. Advanced Synthesis & Catalysis, volume 345, issue 3, Pages 383–388. {{doi, 10.1002/adsc.200390043 Since they are carried out in water, these procedures generally give the dihydroxy derivative. It is also prepared by the oxidation of glycerol with the help of bismuth(III) nitrate.

References

Dicarboxylic acids Deliquescent materials Alpha-keto acids

Synthesis

See also

References