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

The title compound, C15H14N2O4, was prepared from 3,4-dihydroxybenzaldehyde and 2-methoxybenzhydrazide in absolute methanol. An intramolecular N–H⋯O hydrogen bond makes an S(6) ring motif and the dihedral angle between the aromatic rings is 3.2 (3)°. The meta-O atom is disordered over two positions in a 0.809 (6):0.191 (6) ratio. The crystal structure features O—H⋯N and O—H⋯O hydrogen bonds.

The title compound, C 15 H 14 N 2 O 4 , was prepared from 3,4dihydroxybenzaldehyde and 2-methoxybenzhydrazide in absolute methanol. An intramolecular N-HÁ Á ÁO hydrogen bond makes an S(6) ring motif and the dihedral angle between the aromatic rings is 3.2 (3) . The meta-O atom is disordered over two positions in a 0.809 (6)

Tong Shen, Guoli Li and Bin Zheng Comment
In recent years, benzohydrazone derivatives have received much attention especially for their structures and biological aspects (Horkaew et al., 2012;Rassem et al., 2012;Zhang et al., 2012;Fun et al., 2011). We report herein the title new benzohydrazone derivative, (I).

Experimental
The title compound was prepared by stirring 3,4-dihydroxybenzaldehyde (1 mmol, 0.14 g) and 2-methoxybenzohydrazide (1 mmol, 0.17 g) in absolute methanol (30 ml). The mixture was refluxed for 1 h. The solution was then cooled to room temperature. Colorless blocks were recrystallized from methanol by slow evaporation of the solvent at room temperature after a few days.

Refinement
The amide H atom was located in a difference map and refined isotropically [N-H = 0.90 (1) Å]. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with C-H = 0.93 Å for aromatic and CH and 0.96 Å for CH 3 atoms, O-H = 0.82 Å. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl and hydroxyl H atoms and 1.2U eq for the remaining H atoms. The O3 atom is disordered over two sites with occupancies of 0.809 (2) and 0.191 (2), respectively.

Figure 2
A crystal packing diagram of the title compound viewed along the a axis. Hydrogen bonds were drawn as dashed lines.

N′-(3,4-Dihydroxybenzylidene)-2-methoxybenzohydrazide
Crystal data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.24 e Å −3 Δρ min = −0.18 e Å −3 Special details 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (