Malonic acid

Malonic acid

IUPAC name	propanedioic acid
Other names	methanedicarboxylic acid
Identifiers
CAS number	[141-82-2]
SMILES	O=C(O)CC(O)=O
Properties
Molecular formula	C₃H₄O₄
Molar mass	104.03 g/mol
Density	1,619 g/cm³, Solid
Melting point	135-136°C (408-409 K)
Boiling point	Decomposes
Solubility in water	Completely Soluble
Hazards
MSDS	External MSDS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Malonic acid (IUPAC systematic name: propanedioic acid) is a dicarboxylic acid with structure C H₂(COOH)₂. The ionised form of malonic acid, as well as its esters and salts, are known as malonates. For example, diethyl malonate is malonic acid's ethyl ester. The name originates from Latin malum, meaning apple.

[edit] Biochemistry

The calcium salt of malonic acid occurs in high concentrations in beetroot. It exists in its normal state as white crystals. Malonic acid is the archetypal example of a competitive inhibitor: it acts against succinate dehydrogenase (complex II) in the respiratory electron transport chain.

A classical preparation of malonic acid starts from acetic acid^[1]. This acid is chlorinated to chloroacetic acid. Sodium carbonate generates the sodium salt which is then reacted with sodium cyanide to the cyano acetic acid salt in a nucleophilic substitution. The nitrile group can be hydrolysed with sodium hydroxide to sodium malonate and acidification affords malonic acid.

In a well known reaction malonic acid condenses with urea to barbituric acid. Malonic acid is frequently used as an enolate in Knoevenagel condensations or condensed with acetone to form Meldrum's acid. Its esters are also used for the ^-CH₂COOH synthon in the malonic ester synthesis.