2-Ethoxy-4-[2-(3-nitrophenyl)hydrazonomethyl]phenol

The title Schiff base compound, C15H15N3O4, was prepared from a condensation reaction of 3-ethoxy-4-hydroxybenzaldehyde and 3-nitrophenylhydrazine. The molecule is nearly planar; the dihedral angle between the hydroxybenzene ring and the nitrobenzene ring is 6.57 (7)°. O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonding helps to stabilize the crystal structure.

The title Schiff base compound, C 15 H 15 N 3 O 4 , was prepared from a condensation reaction of 3-ethoxy-4-hydroxybenzaldehyde and 3-nitrophenylhydrazine. The molecule is nearly planar; the dihedral angle between the hydroxybenzene ring and the nitrobenzene ring is 6.57 (7) . O-HÁ Á ÁO, O-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonding helps to stabilize the crystal structure.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: XU2611).

Comment
The chemistry of Schiff base has attracted a great deal of interest in recent years. These compounds play an important role in the development of various proteins and enzymes (Kahwa et al., 1986;Santos et al., 2001). As part of our study of the coordination chemistry of Schiff bases, we synthesized the title compound and determined its crystal structure.
The molecular structure of (I) is shown in Fig. 1. The hydroxybenzene ring and the nitrobenzene ring is roughly co-planar, making a dihedral angle of 6.57 (7)°. Intramolecular O-H···O hydrogen bond and intermolecular O-H···N and C-H···O hydrogen bonds are observed (Table 1), they help to stabilize the crystal structure ( Fig. 2).
Experimental 2-Nitrophenylhydrazine (1 mmol, 0.153 g) was dissolved in anhydrous ethanol (15 ml). The solution was stirred for several min at 351 K, 3-ethoxy-4-hydroxybenzaldehyde (1 mmol, 0.166 g) in ethanol (8 mm l) was added dropwise and the mixture was stirred at refluxing temperature for 2 h. The solid product was isolated and recrystallized from methanol, red single crystals were obtained after 3 d.

Refinement
Hydroxy H atom was located in a difference Fourier map and refined isotropically. The other H atoms were positioned geometrically and refined as riding with C-H = 0.93 (aromatic), 0.97 (methylene), 0.96 Å (methyl) and N-H = 0.86 Å, with U iso (H) = 1.5U eq (C) for methyl H and U iso (H) = 1.2U eq (C,N). Fig. 1. The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level, showing intramolecular hydrogen bonds as dashed line.  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 Rfactors(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.