Citraconic acid
Names
Preferred IUPAC name
(2Z)-2-Methylbut-2-enedioic acid
Other names
2-Methylmaleic acid
Citraconate
Methylmaleic acid
cis-Methylbutenedioic acid
Identifiers
3D model (JSmol)
3DMet
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.007.145
EC Number
  • 207-858-7
KEGG
UNII
  • InChI=1S/C5H6O4/c1-3(5(8)9)2-4(6)7/h2H,1H3,(H,6,7)(H,8,9)/b3-2- checkY
    Key: HNEGQIOMVPPMNR-IHWYPQMZSA-N checkY
  • O=C(O)\C=C(/C(=O)O)C
Properties
C5H6O4
Molar mass 130.099 g·mol−1
Appearance Monoclinic crystals[1]
Density 1.62 g/cm3[1]
Melting point ~90 °C (decomposition)[1]
Freely soluble[1]
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302
P264, P270, P301+P312, P330, P501
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. The alkene is cis. The related trans alkene is called 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.[2]

Steps in conversion of citric acid to citraconic acid.

In the laboratory, citraconic acid can be produced by thermal isomerization of itaconic acid anhydride to give citraconic anhydride, which can be hydrolyzed to citraconic acid.[3] The required itaconic acid anhydride is obtained by dry distillation of citric acid.

References

  1. 1 2 3 4 5 Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123
  2. ↑ Kurt Lohbeck; Herbert Haferkorn; Werner Fuhrmann; Norbert Fedtke. "Maleic and Fumaric Acids". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a16_053. ISBN 978-3527306732.
  3. ↑ 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.
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