2-Chloro-1-(4-hydroxyphenyl)ethanone

The asymmetric unit of the title compound, C8H7ClO2, consists of two independent molecules, with comparable geometries. Both molecules are approximately planar (r.m.s. deviations = 0.040 and 0.064 Å for the 11 non-H atoms). In the crystal, molecules are linked via intermolecular O—H⋯O and C—H⋯O hydrogen bonds into chains two molecules thick along (-101).

The asymmetric unit of the title compound, C 8 H 7 ClO 2 , consists of two independent molecules, with comparable geometries. Both molecules are approximately planar (r.m.s. deviations = 0.040 and 0.064 Å for the 11 non-H atoms). In the crystal, molecules are linked via intermolecular O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds into chains two molecules thick along (101).
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009  In view of the importance of α-haloketones in heterocyclic synthesis and their reactivity towards oxygen nucleophiles (Erian et al., 2003), the crystal structure of title compond (I) is reported. The crystal structure of the bromo analogue of the title compound has also been reported (Qing & Zhang, 2009).
The asymmetric unit ( Fig. 1) of the title compound consists of two independent molecules (A and B), with comparable geometries. Both molecules (A and B) are approximately planar (r.m.s. deviation = 0.040 and 0.064 Å, respectively, for the eleven non-H atoms). Bond lengths (Allen et al., 1987) and angles are within normal ranges and are comparable with a related structure (Fun et al., 2012).

Refinement
O-bound hydrogen atoms were located in a difference Fourier map and refined freely with O-H = 0.814 (17) -0.840 (17) Å. The remaining H atoms were positioned geometrically and refined using a riding model with C-H = 0.95 or 0.99 Å and U iso (H) = 1.2 U eq (C).

Figure 2
The crystal structure of the title compound, viewed along the b axis. H atoms not involved in hydrogen bonds (dashed lines) have been omitted for clarity.  (Cosier & Glazer, 1986) operating at 100.0 (1) K. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Cl1A 1.09654 (