1-[3-Methoxy-4-(prop-2-yn-1-yloxy)phenyl]ethanone

In the title compound, C12H12O3, the methoxy and prop-2-ynyloxy groups are nearly coplanar with the attached benzene ring [C—O—C—C torsion angles = 1.2 (3) and 2.2 (3)°, respectively]. In the crystal, inversion dimers linked by pairs of C—H⋯O interactions occur.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: NC2210).

Comment
Lignin is natural polymer occurring in plant cell walls and considered to be the second most abundant biopolymer after cellulose and the β-O-4 structure is the most abundant substructure in lignin (Cathala B. et al., 2003). Lignin is an amorphous polyphenolic material arising from an enzyme-mediated dehydrogenate polymerization of three major phenylpropanoid monomers, i. e., coniferyl, sinapyl and p-coumaril alcohol. Therefore, lignin can be oxidized to produce syringaldehyde, vanillin, p-hydroxybenzaldehyde and acetovanillone etc. Acetovanillone and vanillin are usually used to synthesize lignin mimics (Kishimoto T. et al., 2005). In order to prepare well defined linear lignin mimics composed of the β-O-4 structure by "Click Chemistry" using acetovanillone, an intermediate product C 12 H 12 O 3 , the title compound was synthesized and identified by crystal structure analysis. In the molecular structure of the title compound, the acetophenone unit is almost a planar with a torsion angle C5-C6-C7-O1, -3.5 (3)° (Fig. 1). In addition, the methoxy group and the prop-2-ynyloxy group are nearly coplanar with the attached benzene ring [C9-O2-C4-C5 = 1.2 (3)° and C10-O3-C3-C2, 2.2 (3)°].
In the crystal structure weak intermolecular C terminal alkynes -H···O methoxy interactions aref found.

Experimental
A mixture of 4'-hydroxy-3'-methoxyacetophenon (5 mmol), propargyl bromide (5 mmol) and triethylamine (5 mmol) was stirred in acetone (20 ml) at 353 K. After completion of the reaction (TLC monitoring), the reaction mixture was diluted with ether (100 ml) and washed with water 3 times. The organic phase was dried over with anhydrous Na 2 SO 4 and concentrated to dryness in vacuo. The obtained crude crystalline was purified by column chromatography to obtain a pure white solid.
Colourless single crystals suitable for X-ray crystallographic analysis were grown by slow evaporation of an ethyl actate solution of the title compound.

Refinement
The H atoms were fixed geometrically and allowed to ride on the attached non-H atoms, with C-H = 0.93-0.97 Å, and with U iso (H) = 1.5 U eq (C) for methyl H atoms and 1.2 U eq (C) for all other atoms.

Special details
Experimental. Absorption correction: semi-empirical absorption based on psi-scan (North et al., 1968) 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 > σ(F 2 ) is used only for calculating Rfactors(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq O1 0.02729 (