3-Acetyl-4-hydroxyphenyl acrylate

In the title compound, C12H12O4, the hydroxy O and the C and O atoms of the acetyl group are almost coplanar [maximum deviation = 0.0356 (1) Å] with the benzene ring. The dihedral angle between the benzene ring and the plane through the non-H atoms of the methacryloyloxy group is 86.1 (1)°. In the crystal structure, molecules are linked by two C—H⋯O hydrogen bonds, forming dimers with graph-set descriptor R 2 2(16). A strong intramolecular O—H⋯O hydrogen bond is also observed.

In the title compound, C 12 H 12 O 4 , the hydroxy O and the C and O atoms of the acetyl group are almost coplanar [maximum deviation = 0.0356 (1) Å ] with the benzene ring. The dihedral angle between the benzene ring and the plane through the non-H atoms of the methacryloyloxy group is 86.1 (1) . In the crystal structure, molecules are linked by two C-HÁ Á ÁO hydrogen bonds, forming dimers with graph-set descriptor R 2 2 (16). A strong intramolecular O-HÁ Á ÁO hydrogen bond is also observed.

Comment
Acetophenones are useful synthons for the preparation of a wide variety of polyphenolic compounds such as chalcones and flavones (Parmar et al., 1996). Acetophenone derivatives have shown many interesting biological properties such as anti-inflammatory (Sala et al., 2001;Favier et al., 1998), cytotoxic and choleretic (Suksamrarn et al., 1997) activities. Acetophenone is also used as a solvent for cellulose ethers and esters for the production of alcohol-soluble resins. 2-Hydroxy-4methoxybenzophenone is used on an industrial scale as an ultraviolet absorber in cosmetics and plastics. 2-Hydroxyl-4,6dimethoxyacetophenone was isolated from the leaves of the peperomia glabella family. Peperomia glabella is an epiphyte used in Venezuelan folk medicine as an anti-asthmatic.
The molecular structure of the compound is stabilized by a weak intramolecular O-H···O hydrogen bond and the crystal packing is stabilized by intermolecular C-H···O hydrogen bonds. The molecule at (x, y, z) is linked to the symmetry-related molecule at (-1/2 + x, 1/2 -y, -1/2 + z), forming a dimer with graph set descriptor R 2 2 (16) (Bernstein et al., 1995). Propagation of these dimer units generates an infinite molecular chain along the crystallographic c axis. Fig. 2 shows the crystal packing of the compound, viewed approximately down the a axis.
Experimental 2,5-Dihydroxyacetophenone (26.31 mmol, 4.0 g), K 2 CO 3 (31.55 mmol, 4.36 g) and 150 ml of dry acetone were taken up in a 250 ml round bottomed flask and the temperature was maintained at 0 °C. A solution of methacryloyl chloride (26.80 mmol, 2.8 ml) in 20 ml of dry acetone was then added dropwise to the mixture, with constant stirring for 30 min. After the addition was complete the reaction mixture was stirred for another 6 h. The salt formed during the reaction was filtered and the filtrate was washed with water and dried over anhydrous MgSO 4 . The filtrate was concentrated under reduced pressure and the crude product was purified by column chromatography (silica) using a hexane/ethyl acetate mixture (90:10). The product was collected and recrystallized from chloroform to give a crystalline white solid. Yield: 4.5 g (77%); Mp: 65-66 °C.

Refinement
The H atoms attached to C12 were located in a difference map and refined freely. Other H atoms were positioned geometrically and were treated as riding on their parent atoms, with aromatic C-H distances of 0.93 Å, methyl C-H distances of supplementary materials sup-2 0.96 Å; U iso (H) = 1.5U eq (C) for methyl H and 1.2U eq (C) for aromatic H atoms. O-H = 0.82 Å and the isotropic dispacement parameter was refined. The methylene group was free to rotate, but not to tip. Fig. 1. The molecular structure of the title compound, with dispacement ellipsoids drawn at the 30% probability level. Hydrogen atoms are shown as spheres of arbitrary radius.  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.