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

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 with formula C₃H₂O₅ or HO-(C=O)₃-OH.

Mesoxalic acid is both a dicarboxylic acid

Dicarboxylic acid

Dicarboxylic acids are organic compounds that contain two carboxylic acid functional groups. In molecular formulae for dicarboxylic acids, these groups are often written as HOOC-R-COOH, where R may be an alkyl, alkenyl, alkynyl, or aryl group...

 and a ketonic acid. It readily loses two proton

Proton

The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....

s to yield the divalent

Valence (chemistry)

In chemistry, valence, also known as valency or valence number, is a measure of the number of bonds formed by an atom of a given element. "Valence" can be defined as the number of valence bonds...

 anion C₃O₅²⁻, called mesoxalate, oxomalonate, or ketomalonate. These terms are also used for salts containing this anion, such as sodium mesoxalate, Na₂C₃O₅); and for ester

Ester

Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...

s containing the -C₃O₅- or -O-(C=O)₃-O- moiety

Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

, such as diethyl mesoxalate, C₂H₅)₂C₃O₅. Mesoxalate is one of the oxocarbon anion

Oxocarbon anion

In chemistry, an oxocarbon anion is a negative ion consisting solely of carbon and oxygen atoms, and therefore having the general formula CxOyn− for some integers x, y, and n....

s, which (like carbonate

Carbonate

In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....

 CO₃²⁻ and oxalate

Oxalate

Oxalate , is the dianion with formula C2O42− also written 22−. Either name is often used for derivatives, such as disodium oxalate, 2C2O42−, or an ester of oxalic acid Oxalate (IUPAC: ethanedioate), is the dianion with formula C2O42− also written (COO)22−. Either...

 C₂O₄²⁻) consist solely of carbon

Carbon

Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 and oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

.

Mesoxalic acid readily absorbs and reacts with water to form a product commonly called "mesoxalic acid (mono)hydrate", more properly dihydroxymalonic acid

Dihydroxymalonic acid

Dihydroxymalonic acid is an organic compound with formula C3H4O6 or HO--C2--OH, found in some plants such as alfalfa and in beet molasses.The compound may also be called dihydroxymesoxalic acid, dihydroxypropanedioic acid...

, HO-(C=O)-C(OH)₂-(C=O)-OH. In product catalogs and other contexts, the terms "mesoxalic acid", "oxomalonic acid", etc. often refer to this "hydrated" compound. In particular, the product traded as "sodium mesoxalate monohydrate" is almost always sodium dihydroxymalonate.

Synthesis

Mesoxalic acid can be obtained synthetically by hydrolysis

Hydrolysis

Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

 of alloxan

Alloxan

Alloxan is an oxygenated pyrimidine derivative. It is present as alloxan hydrate in aqueous solution.-History:...

 with baryta water, by warming caffuric acid with lead acetate

Lead acetate

Lead acetate can refer to:* Lead acetate , Pb4* Lead acetate , Pb2...

 solution, or from glycerin diacetate

Acetate

An acetate is a derivative of acetic acid. This term includes salts and esters, as well as the anion found in solution. Most of the approximately 5 billion kilograms of acetic acid produced annually in industry are used in the production of acetates, which usually take the form of polymers. In...

 and concentrated nitric acid

Nitric acid

Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...

 in the cold. The product can be obtained also by oxidation of tartronic acid

Tartronic acid

Tartronic acid or 2-hydroxymalonic acid is a dicarboxylic acid with the structural formula of HOOCCHCOOH.Its derivative, 2-methyltartronic acid, is isomalic acid.-Uses:...

or glycerol

Glycerol

Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

. Since they are carried out in water, these procedures generally give the dihydroxy derivative.