1-(4-Fluorophenyl)-3-hydroxy-3-phenylprop-2-en-1-one

In the crystal structure the title compound, C15H11FO2, the molecule exists in the enol form. It is stabilized by an intramolecular O—H⋯O hydrogen bond, in which the donor O—H and acceptor H⋯O distances are almost equal. The dihedral angle between the two benzene rings is 22.30 (4)°.

In the crystal structure the title compound, C 15 H 11 FO 2 , the molecule exists in the enol form. It is stabilized by an intramolecular O-HÁ Á ÁO hydrogen bond, in which the donor O-H and acceptor HÁ Á ÁO distances are almost equal. The dihedral angle between the two benzene rings is 22.30 (4) .

Data collection
Bruker SMART CCD area-detector diffractometer Absorption correction: multi-scan (SADABS; Sheldrick, 1996) Table 1 Hydrogen-bond geometry (Å , ). (19) 157 (2) Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.  1,3-Diketones posses a broad spectrum of useful and sometimes unique chemical properties, which make them extremely attractive as intermediates in syntheses (Hasegawa et al., 1997). They are also used in the chemistry of metallocomplexes (Ma et al., 1999;Yoshida et al., 2005;Jang et al., 2006). 1,3-Diketone structures have received increasing attention due to their enolic tautomeric forms and their ability to form strong intermolecular or intramolecular hydrogen bonds (Gilli et al., 2004). The crystal structure of the title compound ( Fig. 1) is in the enol form, stabilized by an intramolecular hydrogen bond (Table 2). The bond lengths in the diketone fragment are either significantly shorter than normal single bonds or significantly longer than normal double bonds (Table 1). This shows that the structure displays a strong delocalization of double bonds in this region. The geometric data are in agreement with reported literature values (Bertolasi et al., 1991;Wang et al., 2006).
The dihedral angle between the two aromatic rings is 22.30 (4)°.
Experimental 1-(4-Fluorophenyl)ethanone (1.38 g, 0.01 mol), ethyl benzoate (1.50 g, 0.01 mol), NaNH 2 (0.78 g, 0.02 mol) and dry ether (40 ml) were placed in a round bottom flask. The mixture was stirred 6 h at room temperature under a blanket of nitrogen, acidified with dilute hydrochloric acid, and stirring was continued until all solids dissolved. The ether layer was separated and washed with saturated NaHCO 3 solution, dried over anhydrous Na 2 SO 4 and the solvent was removed by evaporation.
The residual solid was recrystallized from an ethanol solution to give the title compound (yield 1.27 g, 52.4%, m.p. 351 K).
Crystals suitable for X-ray diffraction were grown by slow evaporation of CHCl 2 -EtOH (1:5) solutions at room temperature.

Refinement
The H atom of the hydroxyl group was located in a difference Fourier map and its position was refined freely, with U iso (H) = 1.5 U iso (O). The other H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C-H distances of 0.93 to 0.97 Å, and with U iso (H) = 1.2 U eq (C). Fig. 1