(E)-N′-(4-Hydroxybenzylidene)-4-hydroxybenzohydrazide methanol solvate

The title compound, C14H12N2O3·CH4O, consists of a Schiff base molecule and a methanol molecule of crystallization. The Schiff base molecule is nearly planar, the dihedral angle between the planes of the two benzene rings being 7.2 (2)°. The molecule exists in the trans configuration with respect to the methylidene unit. In the crystal structure, the Schiff base and methanol molecules are linked through O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds, forming a three-dimensional network.


Structure Reports Online
In the structure of the title compound ( Fig. 1) the Schiff base molecule is nearly planar, the dihedral angle between the two benzene rings being 7.2 (2)°. The molecule exists in a trans configuration with respect to the methylidene unit. The In the crystal structure, the Schiff base molecules and the methanol molecules are linked through intermolecular O-H···O, N-H···O and O-H···N hydrogen bonds (Table 1), forming a three dimensional network (Fig. 2).

Experimental
The compound was prepared by refluxing 4-hydroxybenzaldehyde (1.0 mol) with 4-hydroxybenzohydrazide (1.0 mol) in methanol (100 ml). Excess methanol was removed from the mixture by distillation. The colorless solid product was filtered and washed three times with methanol. Colorless block crystals of the title compound were obtained from a methanol solution by slow evaporation in air.

Refinement
H2A was located in a difference Fourier map and refined isotropically, with the N-H distance restrained to 0.90 (1)Å. Other H atoms were placed in calculated positions (C-H = 0.93 -0.96 Å, O-H = 0.82 Å) and refined as riding with U iso (H) = 1.2U eq (C) and 1.5U eq (O and methyl). A rotating group model was used for the methyl group of the methanol. Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids for the non-hydrogen atoms. Hydrogen atoms are shown as spheres of arbitrary radius. The dashed line indicates a hydrogen bond.

Special details
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.