1-[2-Hydroxy-4-(prop-2-yn-1-yloxy)phenyl]ethanone

In the title compound, C11H10O3, there is an intramolecular O—H⋯O hydrogen bond generating an S(6) ring motif. The O atom of the hydroxy group deviates by 0.0200 (1) Å from the benzene ring to which it is attached. The propyne group is almost linear, the C—C C angle being 177.83 (15)°, and is almost coplanar with the benzene ring; the C—C—O—C torsion angle being only −1.1 (2)°. In the crystal, molecules are linked via C—H⋯O hydrogen bonds, forming infinite C(11) chains running parallel to [103]. These chains are linked by a pair of C—H⋯O hydrogen bonds, enclosing R 2 2(8) inversion dimers, forming a corrugated two-dimensional network lying parallel to (103).


Comment
Schiff bases derived from amines and substituted benzaldehydes exhibit antibacterial, anticancer and antitumour activities (Zhao et al., 2007). Several benzaldoximes, benzaldehyde-O-ethyloximes and acetophenone oximes were synthesized and evaluated as tyrosinase inhibitors (Ley & Bertram, 2001). Bis-salicylaldehydes has been shown to exhibited greater inhibitory activity than salicylaldehyde (Delogu et al., 2010). In view of these potential applications and in continuation of our work on the crystal structures of benzaldehyde derivatives, we synthesized the title compound and report herein on its crystal structure.
The molecular structure of the title compound is stabilized by an O-H···O intramolecular hydrogen bond ( Fig. 1 and Table 1), which forms an S(6) graph-set motif (Bernstein et al., 1995). The hydroxyl O atom, O1, deviates by 0.0200 (1) Å from the benzene ring (C1-C6) to which it is attached. The oxygen atom substituted propyne group is slightly twisted from the benzene ring (C1-C6) to which it is attached as evidenced by the torsion angle C6-C5-O3-C9 = -1.1 (2) °. The propyne group is almost linear, the C9-C10≡C11 angle being 177.83 (15)°, and it is also in the flagpole position on atom O3. The mean plane of the acetaldehyde group makes a dihedral angle of 0.39 (9)° with the benzene ring (C1-C6), indicating that they are almost coplanar.
In the crystal, molecules are linked via C-H···O hydrogen bonds forming infinite C(11) chains running parallel to direction [103]. These chains are linked via a pair of C-H···O hydrogen bonds, enclosing R 2 2 (8) inversion dimers, forming wave-like two-dimensional networks lying parallel to (103); see Table 1 and Fig. 2.

Experimental
Equimolar amounts of 3-bromopropyne (10 mmol), 2,4-dihydroxyacetophenone (10 mmol) and potassium carbonate (15 mmol) were suspended in dried acetone (30 ml) and refluxed for 5 h. The reaction mixture was filtered while hot to remove insoluble impurities, neutralized with water and then extracted with ethyl acetate and dried with Na 2 SO 4 . The extracts were concentrated to obtain a brown solid which was then purified by column chromatography over SiO 2 by eluting with a mixture of 5% ethyl acetate in n-hexane. Evaporation of the purified extract yielded the title compound in the form of a pure white solid [Yield: 83%]. Colourless block-like crystals, suitable for X-ray diffraction analysis, were obtained by the slow evaporation of a solution in ethyl acetate.

Refinement
All H atoms could be located in difference Fourier maps. The methyl H atoms were refined with U iso (H) = 1.5U eq (C). The

Figure 1
The molecular structure of the title molecule, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level. The intramolecular O-H···O hydrogen bond is shown as a dashed line (see Table 1 for details)

Figure 2
A view along the a axis of the crystal packing of the title compound. The hydrogen bonds are shown as dashed lines (see Table 1 for details; H atoms not involved in hydrogen bonding have been excluded for clarity).  (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.020 (4)

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. 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 > 2sigma(F 2 ) is used only for calculating R-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.