2-Hydroxy-3-methyl-2-cyclopenten-1-one

2-Hydroxy-3-methyl-2-cyclopenten-1-one is an organic compound related to 1,2-cyclopentanedione. It is the enol tautomer of the diketone 3-methylcyclopentane-1,2-dione. Being an enol, the compound is often called methylcyclopentenolone. It is a colorless solid.

2-Hydroxy-3-methyl-2-cyclopenten-1-one

Names
Preferred IUPAC name 3-Methylcyclopentane-1,2-dione
Other names Maple lactone, Methylcyclopentenolone, Corylon
Identifiers
CAS Number	765-70-8 Y 80-71-7 (enol form)
3D model (JSmol)	Interactive image
ChemSpider	55153 Y
ECHA InfoCard	100.001.186
EC Number	212-154-8
PubChem CID	61209 6660 (enol form)
UNII	627E92X64B Y
CompTox Dashboard (EPA)	DTXSID4035128
InChI InChI=1S/C6H8O2/c1-4-2-3-5(7)6(4)8/h4H,2-3H2,1H3 Y Key: OACYKCIZDVVNJL-UHFFFAOYSA-N Y
SMILES CC1C(=O)C(=O)CC1
Properties
Chemical formula	C6H8O2
Molar mass	112.128 g·mol−1
Density	1.312 g/cm3
Melting point	104–108 °C (219–226 °F; 377–381 K)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis and structure

The compound is prepared by base-catalyzed condensation of 1-hydroxyhexane-2,5-dione, a derivative of hydroxymethylfurfural.^[2]

The structure has been confirmed by X-ray crystallography.^[2] Quantum calculations also indicate that the enol is strongly favored relative to the diketo tautomer. Furthermore, the enolization occurs at the methyl-substituted carbon.^[3]

Use and occurrence

It is one of many products from the pyrolysis of lignocellulose.^[4]

It is used in flavors and perfumery for its maple- or caramel-like odor.^[5] It contributes to the flavor or odor of many foods including wines, coffee, paprika, and salmon. It is sometimes called maple lactone because it occurs in maple syrup (it is not, however, a lactone).^[6]

See also

• 1,2-Cyclopentanedione