Citraconic acid

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Citraconic acid
Citraconic acid.svg
IUPAC name
(2Z)-2-Methylbut-2-enedioic acid
Other names
Citraconate; Methylmaleic acid; cis-Methylbutenedioic acid
3D model (JSmol)
ECHA InfoCard 100.007.145
Molar mass 130.10 g·mol−1
Appearance Monoclinic crystals[1]
Density 1.62 g/cm3[1]
Melting point ~90 °C (decomposition)[1]
Freely soluble[1]
R-phrases (outdated) R22[2]
S-phrases (outdated) S36[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Citraconic acid is an organic compound with the formula CH3C2H(CO2H)2. It is a white solid. It is the cis-isomer of mesaconic acid. It is one of the pyrocitric acids formed upon the heating of citric acid.[1] Citraconic acid can be produced, albeit inefficiently, by oxidation of xylene and methylbutanols. The acid displays the unusual property of spontaneously forming the anhydride, which, unlike maleic anhydride, is a liquid at room temperature.[3]

In the laboratory, citraconic acid can be produced by heating, itaconic acid anhydride to give citraconic acid anhydride, which can be hydrolyzed to citraconic acid.[4] The required itaconic acid anhydride is obtained by dry distillation of citric acid.


  1. ^ a b c d e Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123 
  2. ^ a b Citraconic acid Archived January 19, 2012, at the Wayback Machine.
  3. ^ Kurt Lohbeck; Herbert Haferkorn; Werner Fuhrmann; Norbert Fedtke (2005), "Maleic and Fumaric Acids", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a16_053 
  4. ^ R. L. Shriner; S. G. Ford; l. J. Roll (1931). "Citraconic Anhydride and Citraconic Acid". Org. Synth. 28: 28. doi:10.15227/orgsyn.011.0028.