4-[2-(4-Hydroxyphenyl)ethyl]-3-propyl-1H-1,2,4-triazol-5(4H)-one

The asymmetric unit of the title compound, C13H17N3O2, contains eight crystallographically independent molecules. The planes of the benzene and triazole rings in the eight molecules make dihedral angles of 5.53 (13), 9.33 (13), 19.28 (11), 17.36 (8), 12.84 (12), 8.03 (8), 19.97 (11), and 7.98 (8)°. The eight molecules in the asymmetric unit are linked by intermolecular O—H⋯O and N—H⋯O hydrogen bonds, forming a three-dimensional network.


Related literature
Eight independent molecules of the title compound (I) in the asymmetric unit are shown in Fig. 1 and labelled as A to H.
In the crystal structure ( Fig. 3), the molecules are linked through O-H···O and N-H···O intra-and intermolecular hydrogen bonds (Table 1) to form a three-dimensional network.

Experimental
A solution of 4-(4-metoksifeniletil)-5-propil-2H-1,2,4-triazol-3(4H)-on (10 mmol) in chloroform (100 ml) was added to a solution of boron tribromide (10 mmol) in chloroform (200 ml) at 273 K. The reaction mixture was poured into ice containing sufficient 50% sodium hydroxide to attain a pH of 10. The addition of concentrated sulfuric acid provided a precipitate that was extracted into ether. The combined organic extract was washed with water and brine, and then dried and concentrated in a vacuum to obtain compounds. The crude product was recrystallized using ethyl acetate and

Figure 1
The eight independent molecules in the asymmetric unit of the title compound, showing the atom-numbering scheme.  One of the eight independent molecules in the asymmetric unit to show clearly the atomic labelling (molecule A). The other seven molecules are labelled in a similar manner.  The crystal packing of the title compound viewed along the c axis, showing the formation of hydrogen bonded dimers further linked by additional hydrogen bonding. The hydrogen bonds as dashed lines.

Special details
Experimental. CrysAlis RED, (Oxford Diffraction, 2007) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. (Clark & Reid, 1995). Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.