Citraconic acid

Citraconic acid
Names
	Preferred IUPAC name (2Z)-2-Methylbut-2-enedioic acid
	Other names 2-Methylmaleic acid; Citraconate; Methylmaleic acid; cis-Methylbutenedioic acid
Identifiers
CAS Number	498-23-7 ;
3D model (JSmol)	Interactive image;
3DMet	B00408;
ChEBI	CHEBI:17626 ;
ChemSpider	553689 ;
DrugBank	DB04734 ;
ECHA InfoCard	100.007.145
EC Number	207-858-7;
KEGG	C02226;
PubChem CID	643798;
UNII	0RQ6CXO9KD ;
	InChI InChI=1S/C5H6O4/c1-3(5(8)9)2-4(6)7/h2H,1H3,(H,6,7)(H,8,9)/b3-2- Key: HNEGQIOMVPPMNR-IHWYPQMZSA-N ;
	SMILES O=C(O)\C=C(/C(=O)O)C;
Properties
Chemical formula	C5H6O4
Molar mass	130.099 g·mol−1
Appearance	Monoclinic crystals[1]
Density	1.62 g/cm3[1]
Melting point	~90 °C (decomposition)[1]
Solubility in water	Freely soluble[1]
Hazards
GHS pictograms
GHS Signal word	Warning
GHS hazard statements	H302
GHS precautionary statements	P264, P270, P301+312, 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. 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.[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

Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123
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.
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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[Merck-1] Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123

[ullmann-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.

[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.