3,5-Dihydroxy-2-methyl-4H-pyran-4-one

In the title compound, C6H6O4, inter- and intramolecular hydrogen bonds are observed which help to establish the crystal structure. There are weak π–π interactions between pyran rings separated by 3.5692 (9) Å.

In the title compound, C 6 H 6 O 4 , inter-and intramolecular hydrogen bonds are observed which help to establish the crystal structure. There are weakinteractions between pyran rings separated by 3.5692 (9) Å .
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PV2074).

Comment
The title compound, 3,5-dihydroxy-2-methyl-pyran-4-one, (I) was identified as a decomposition product in the stored solution of orange juice (Shinoda, et al., 2004). We report here the crystal structure of the title compound ( Fig. 1) which was isolated from Hydrocotyle sibthorpoioides Lam. The structure of (I) is stabilized by two strong intermolecular hydrogen bonds of the type O-H···O and a weak intermolecular interaction of the type C-H···O. Intramolecular interactions are also observed which result in five membered rings; details are given in Table 1. There is indication of π-π interactions between the pyran rings lying about inversion centers with minimum separation of 3.5692 (9) Å. The crystal structures of 2-hydroxymethyl analogue (Yao et al., 2005) and 5-hydroxy-3-methoxy-pyran-4-one (Gibbons et al., 2000) have been reported.

Experimental
Dried powder of Hydrocotyle sibthorpoioides Lam was exacted with EtOH and the extract was concentrated in vacuo.
The residue was subjected to silical-gel coloumn chromatography. Elution with chloroform-methanol (95:5 v/v) yielded the title compound. Crystals suitable for XRD study were grwon from a solution of methanol at room temperature by slow evaporation.

Refinement
All H atoms were located from difference map and allowed to refine freely. Fig. 1. A view of the molecule of (I). Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-supplementary materials sup-3 factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.