(E)-N′-(2,3-Dihydroxybenzylidene)-4-methoxybenzohydrazide

The molecule of the title benzohydrazide derivative, C15H14N2O4, is twisted and exists in a trans conformation with respect to the C=N double bond. The dihedral angle between the benzene rings is 56.86 (9)° and the C atom of the methoxy group deviates slightly [C—O—C—C = −10.4 (3)°] from its attached benzene ring. An intramolecular O—H⋯N hydrogen bond generates an S(6) ring. In the crystal, molecules are linked by N—H⋯O and bifurcated N—H⋯(O,O) hydrogen bonds, as well as weak C—H⋯O interactions, into two-dimensional networks lying parallel to the bc plane. A weak C—H⋯π interaction also occurs.

The molecule of the title benzohydrazide derivative, C 15 H 14 N 2 O 4 , is twisted and exists in a trans conformation with respect to the C N double bond. The dihedral angle between the benzene rings is 56.86 (9) and the C atom of the methoxy group deviates slightly [C-O-C-C = À10.4 (3) ] from its attached benzene ring. An intramolecular O-HÁ Á ÁN hydrogen bond generates an S(6) ring. In the crystal, molecules are linked by N-HÁ Á ÁO and bifurcated N-HÁ Á Á(O,O) hydrogen bonds, as well as weak C-HÁ Á ÁO interactions, into two-dimensional networks lying parallel to the bc plane. A weak C-HÁ Á Á interaction also occurs.

Comment
Our on-going research on the biological activities of benzohydrazides containing the -CO-NH-N=CH-grouping has led us to synthesize the title compound (I) in order to compare its activity with other related compounds Horkaew et al., 2011). Our results found that (I) exhibits interesting antibacterial and antioxidant activities which will be reported elsewhere with other related benzohydrazide derivatives. Herein the crystal structure of (I) is reported.
In the crystal packing ( Fig. 2), the molecules are linked by N-H···O, and O-H···O hydrogen bonds, as well as with weak C-H···O interactions (Table 1), into two dimensional networks parallel to the bc plane. A C-H···π interaction was also presented (Table 1).
Experimental 4-Methoxybenzohydrazide (2 mmol, 0.33 g) was dissolved in ethanol (10 ml) and a solution of 2,3-dihydroxybenzaldehyde (2 mmol, 0.28 g) in ethanol (10 ml) was then slowly added to it. The mixture was refluxed for around 5 hr. The solution was then cooled to room temperature and left to evaporate in air. The yellow solid product that appeared was collected by filtration and washed with ethanol and dried in air. Yellow blocks of the title compound were obtained after recrystalization from methanol by the slow evaporation of the solvent at room temperature after several days, Mp. 502-503 K.

Refinement
Amide and hydroxy H atoms were located from the difference maps and refined isotropically. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(C-H) = 0.93 Å for aromatic and CH and 0.96 Å for CH 3 atoms. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups. The highest residual electron density peak is located at 0.72 Å from C9 and the deepest hole is located at 1.02 Å from C3. Fig. 1. The molecular structure of the title compound, showing 40% probability displacement ellipsoids. Hydrogen bond is drawn as a dashed line.

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.