Malonic acid

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Not to be confused with malic acid or maleic acid.
Malonic acid
Malonic acid
Malonic-acid-3D-balls.png
Identifiers
CAS number 141-82-2 YesY
PubChem 867
ChemSpider 844 YesY
DrugBank DB02175
ChEBI CHEBI:30794 YesY
ChEMBL CHEMBL7942 YesY
Jmol-3D images Image 1
Properties
Molecular formula C3H4O4
Molar mass 104.06 g mol−1
Density 1.619 g/cm3
Melting point 135–136 °C
Boiling point decomposes
Solubility in water Miscible
Acidity (pKa) pKa1 = 2.83[1]
pKa2 = 5.69[1]
Related compounds
Other anions malonate
Related carboxylic acids acetic acid
oxalic acid
propionic acid
tartronic acid
acrylic acid
butyric acid
succinic acid
fumaric acid
Related compounds propanone
propionaldehyde
propanedial
dimethyl malonate
Hazards
MSDS External MSDS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Malonic acid (IUPAC systematic name: propanedioic acid) is a dicarboxylic acid with structure CH2(COOH)2. The ionized form of malonic acid, as well as its esters and salts, are known as malonates. For example, diethyl malonate is malonic acid's diethyl ester. The name originates from the Greek word μᾶλον (malon) meaning 'apple'.

Biochemistry[edit]

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 classic example of a competitive inhibitor: It acts against succinate dehydrogenase (complex II) in the respiratory electron transport chain.

Preparation[edit]

A classical preparation of malonic acid starts from chloroacetic acid:[2]

Preparation of malonic acid from chloroacetic acid.

Sodium carbonate generates the sodium salt, which is then reacted with sodium cyanide to provide the cyano acetic acid salt via a nucleophilic substitution. The nitrile group can be hydrolyzed with sodium hydroxide to sodium malonate, and acidification affords malonic acid.

Malonic acid was first prepared in 1858 by the French chemist Victor Dessaignes (1800-1885) via the oxidation of malic acid.[3]

Organic reactions[edit]

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

Additionally, the coenzyme A derivative of malonate, malonyl-CoA, is an important precursor in fatty acid biosynthesis along with acetyl CoA. Malonyl CoA is formed from acetyl CoA by the action of acetyl-CoA carboxylase, and the malonate is transferred to an acyl carrier protein to be added to a fatty acid chain.

References[edit]

  1. ^ a b pKa Data Compiled by R. Williams (pdf; 77 kB)
  2. ^ Nathan Weiner, "Malonic acid", Org. Synth. ; Coll. Vol. 2: 376 
  3. ^ See:

External links[edit]