(Z)-4-(2-Hydroxyanilino)pent-3-en-2-one

In the title compound, C11H13NO2, the dihedral angle between the planes defined by the 2-hydroxyphenylamino group and the pent-3-en-2-one mean plane [maximum deviations = 0.0275 (19) and 0.054 (2) Å, respectively] is 31.01 (10)°. There are intramolecular bifurcated N—H⋯(O,O) hydrogen bonds involving the amine NH group and the adjacent carbonyl and hydroxy O atoms. In the crystal, molecules are linked via O—H⋯O hydrogen bonds, forming chains propagating along [100].

In the title compound, C 11 H 13 NO 2 , the dihedral angle between the planes defined by the 2-hydroxyphenylamino group and the pent-3-en-2-one mean plane [maximum deviations = 0.0275 (19) and 0.054 (2) Å , respectively] is 31.01 (10) . There are intramolecular bifurcated N-HÁ Á Á(O,O) hydrogen bonds involving the amine NH group and the adjacent carbonyl and hydroxy O atoms. In the crystal, molecules are linked via O-HÁ Á ÁO hydrogen bonds, forming chains propagating along [100].
The tautomeric properties and conformations of the title compound were investigated by (Kabak et al., 1998). The enol tautomer form of the crystal of the title compound is established by the present crystal structure analysis. The positive photoconductivity of this compound has been studied by (Parekh et al., 2007). The crystal exhibits positive photoconductivity and poor NLO responses, and it is photochromic not thermochromic in the solid state (Moustakali-Mavridis et al., 1978;Hadjoudis et al., 1987).
The molecular structure of the title molecule is shown in Fig. 1. It was prepared by the condensation of acetylacetone and 2-aminophenol and crystallized in the chiral space group P2 1 2 1 2 1 .
The molecule is not planar and the dihedral angle between the two planes defined by O1,C1-C6,N1 and O2,C7-C11 is equal to 31.01 (10) °. The small value of bond N1-C7 (1.346 (2) A°) in comparison to bond N1-C6 (1.416 (3) A°) results in a significant change in the bond angle C7-N1-C6 of 130.76 (17)°. The difference in the C-N bond distances is assumed to be due to the presence of the carbonyl group located at the C10 position. Shortening of the C7-N1 bond length and the large value of the C7-N1-C6 bond angle leads to the existence of an N1-H1···O2 intramolecular hydrogen bond (Table 1) with an S(6) ring motif (Bernstein et al., 1995). The second intramolecular N1-H1···O1 hydrogen bond gives an S(5) ring motif.
In the crystal, molecules are linked via O-H···O hydrogen bonds to form chains propagating along [100] -see Table 1 and Fig. 2.

Experimental
To a ethanol solution (5 ml) of (0.109 g, 1 mmol) of 2-aminophenol was slowly added a ethanol solution (5 ml) of acetylacetone (0.1 g, 1 mmol). The mixture was refluxed with constant stirring under a nitrogen atmosphere for 5 h. The mixture was removed and allowed to cool to rt and the solvent to evaporate slowly. After 20 days yellow crystals of the title compound were obtained. They were washed with ethanol then with diethyl ether.

Refinement
The OH and NH H atoms were located in a difference Fourier map and freely refined. The C-bound H atoms were included in calculated positions and refined using a riding model: C-H = 0.95 and 0.98 Å for CH and CH 3 H atoms, respectively, with U iso (H) = k × U eq (C) where k = 1.5 for methyl H atoms and = 1.2 for other H atoms. In the final cycles of refinement, in the absence of significant anomalous scattering effects, the Friedel pairs were merged and Δf " set to zero.

Figure 1
A view of the molecular structure of the title molecule, with the atom numbering. Displacement ellipsoids are drawn at the 50% probability level. The intramolecular bifurcated N-H···O/O hydrogen bond are shown as dashed lines (see Table   1 for details).  The crystal packing of the title compound viewed along the b axis. The N-H···O and O-H···O hydrogen bonds are shown as dashed lines (see Table 1 for details). Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles 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.