Coumalic acid

Names
Preferred IUPAC name 2-Oxo-2H-pyran-5-carboxylic acid
Other names Cumalic acid
Identifiers
CAS Number	500-05-0
3D model (JSmol)	Interactive image
ECHA InfoCard	100.007.182
PubChem CID	68141
UNII	OB1JPY343G
CompTox Dashboard (EPA)	DTXSID60870569
InChI InChI=1S/C6H4O4/c7-5-2-1-4(3-10-5)6(8)9/h1-3H,(H,8,9) Key: ORGPJDKNYMVLFL-UHFFFAOYSA-N
SMILES C1=CC(=O)OC=C1C(=O)O
Properties
Chemical formula	C6H4O4
Molar mass	140.094 g·mol−1
Melting point	210 °C (410 °F; 483 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Coumalic acid is an organic compound with the molecular formula C₆H₄O₄. Its melting point is around 210 °C.

In laboratory coumalic acid may be obtained by self-condensation of malic acid in fuming sulfuric acid:^[1]

Note that this scheme is incorrect. 4 H2O and 2 CO (carbon monoxide, not carbon dioxide) are liberated during the condensation.