N′-(3-Ethoxy-2-hydroxybenzylidene)-4-hydroxy-3-methoxybenzohydrazide monohydrate

In the title compound, C17H18N2O5·H2O, the dihedral angle between the two aromatic rings is 7.86 (7)° and an intramolecular O—H⋯N hydrogen bond is observed. In the crystal structure, molecules are linked into a three-dimensional network by intermolecular O—H⋯O and N—H⋯O hydrogen bonds.


An intramolecular O-H···N hydrogen bond is observed
In the crystal structure, molecules are linked into a three-dimensional network (  (Table 1).

Experimental
The title compound was prepared by the Schiff base condensation of 2-hydroxy-3-ethoxybenzaldehyde (0.1 mol) and 4-hydroxy-3-methoxybenzohydrazide (0.1 mmol) in 95% ethanol (50 ml). The excess ethanol was removed by distillation. The colourless solid obtained was filtered and washed with ethanol. Single crystals suitable for X-ray diffraction were obtained by slow evaporation of a 95% ethanol solution at room temperature.

Refinement
The imino and water H atoms were located in a difference map and refined with N-H, O-H, and H···H distance restraints of 0.90 (1), 0.85 (1) and 1.37 (2) Å, respectively. Other H atoms were positioned geometrically (C-H = 0.93-0.97 Å, O-H = 0.82 Å) and refined using a riding model, with U iso (H) = 1.2U eq (C) and 1.5U eq (C methyl and O).

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
supplementary materials sup-7