4-(4-Chlorophenyl)piperidin-4-ol

In the title compound, C11H14ClNO, the piperidine ring adopts a chair conformation: the hydroxyl substituent and the N-bound H atom occupy the axial positions, while the benzene ring occupies the equatorial position. In the crystal, the molecules are linked into a centrosymmetric tetramer through strong O—H⋯N and weak N—H⋯O hydrogen bonds; the N and O atoms act as both donor and acceptor for these interactions. The tetramers are further joined by hydrogen bonds into a layer parallel to (100).

In the title compound, C 11 H 14 ClNO, the piperidine ring adopts a chair conformation: the hydroxyl substituent and the Nbound H atom occupy the axial positions, while the benzene ring occupies the equatorial position. In the crystal, the molecules are linked into a centrosymmetric tetramer through strong O-HÁ Á ÁN and weak N-HÁ Á ÁO hydrogen bonds; the N and O atoms act as both donor and acceptor for these interactions. The tetramers are further joined by hydrogen bonds into a layer parallel to (100).
BPS thanks R. L. FineChem, Bangalore, India, for the gift of a sample of the title compound.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IS2520).
The relatively strong and directional O-H···N hydrogen bonds join the molecules of 1, related by two-fold screw axis, into the chains along [010] directions. These chains are interconnected by far weaker N-H···O hydrogen bonds. These two kinds of contacts form centrosymmetric tetramers of the molecules (Fig. 2). In the crystal structures there are the hydrogen-bonded layers of molecules, created by interconnecting chains, in the bc plane (Fig. 3a). There are no directional interactions between neighbouring layers (Fig. 3b).

Experimental
The title compound was obtained as a gift sample from R. L. Fine Chem, Bangalore, India. X-ray quality crystals were obtained by a slow evaporation from an ethyl acetate solution (m.p. 410-413 K).

Refinement
Hydrogen atoms were found in the subsequent difference Fourier maps, and freely refined. Fig. 1. Anisotropic ellipsoid representation of the compound 1 together with atom labelling scheme. The ellipsoids are drawn at 50% probability level, hydrogen atoms are depicted as spheres with arbitrary radii.  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 > 2σ(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.