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;
ChEBI	CHEBI:17626 ;
ChemSpider	553689 ;
DrugBank	DB04734 ;
ECHA InfoCard	100.007.145
EC Number	207-858-7;
KEGG	C02226;
PubChem CID	643798;
UNII	0RQ6CXO9KD ;
CompTox Dashboard (EPA)	DTXSID601019903 ;
	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
Density	1.62 g/cm3
Melting point	~90 °C (decomposition)
Solubility in water	Freely soluble
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302
Precautionary statements	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). verify (what is ?) 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

^ ^a ^b ^c ^d ^e 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. ISBN 978-3-527-30673-2.
^ 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.

[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. ISBN 978-3-527-30673-2.

[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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