5-Pentyl-4-phenylsulfonyl-1H-pyrazol-3-ol

In the title compound, C14H18N2O3S, the 1H-pyrazole ring is approximately planar, with a maximum deviation of 0.005 (1) Å. The dihedral angle formed between the 1H-pyrazole and phenyl rings is 79.09 (5)°. Pairs of intermolecular N—H⋯O and O⋯H⋯N hydrogen bonds form dimers between neighboring molecules, generating R 2 2(10) ring motifs. These dimers are further linked by intermolecular N—H⋯O and O—H⋯N hydrogen bonds into two-dimensional arrays parallel to the ac plane. The crystal structure is also stabilized by C—H⋯π interactions.

In the title compound, C 14 H 18 N 2 O 3 S, the 1H-pyrazole ring is approximately planar, with a maximum deviation of 0.005 (1) Å . The dihedral angle formed between the 1Hpyrazole and phenyl rings is 79.09 (5) . Pairs of intermolecular N-HÁ Á ÁO and OÁ Á ÁHÁ Á ÁN hydrogen bonds form dimers between neighboring molecules, generating R 2 2 (10) ring motifs. These dimers are further linked by intermolecular N-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonds into two-dimensional arrays parallel to the ac plane. The crystal structure is also stabilized by C-HÁ Á Á interactions.

Comment
Pyrazolone derivatives have a broad spectrum of biological activities, being used as analgesic, antipyretic and anti-inflammatory therapeutical drugs (Brogden, 1986;Gursoy et al., 2000). A class of new compounds with the pyrazolone unit has been synthesized and reported to possess antibacterial and antifungal activities (Ragavan et al., 2009(Ragavan et al., , 2010. A new pyrazolone derivative, edaravone (3-methyl-1-phenyl-2-pyrazoline-5-one), is being used as a drug in clinical practice for brain ischemia (Watanabe et al., 1984;Kawai et al., 1997) and the same has been found to be effective against myocardial ischemia (Wu et al., 2002).

Experimental
The compound 5-pentyl-4-(phenylsulfonyl)-1H-pyrazol-3-ol was synthesized according to the procedure available in the literature (Ragavan et al., 2009(Ragavan et al., , 2010, which in turn was dissolved using a THF/water (1:1) mixture. Oxone (4 mmol) was then added and the solution was stirred at room temperature for 3 h. The reaction mixture was diluted with water (20 ml), and then was extracted with ethyl acetate (2 x 50 ml). The combined extract was washed with water (20 ml) and brine solution (10 ml). Crystallization was carried out using absolute ethanol.

Refinement
All hydrogen atoms were located in a difference map and were refined freely   Glazer, 1986) operating at 100.0 (1) K.

5-Pentyl-4-phenylsulfonyl-1H-pyrazol-3-ol
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 S1 0.252485 (