Crystal structure of 2-(2,3-dimethylanilino)-N′-[(1E)-2-hydroxybenzylidene]benzohydrazide

The asymmetric unit of the title compound, C22H21N3O2, consists of two independent molecules (A and B) having differing conformations. The differences mainly concern the dihedral angles which the hydroxyphenyl and dimethylphenyl rings subtend to the central phenylene ring, these being 30.16 (6) and 58.60 (6)° in molecule A and 13.42 (7) and 60.31 (7)° in B. With the exception of the dimethyphenyl substituent, the conformations of the rest of each molecule are largely determined by intramolecular O—H⋯N and N—H⋯O hydrogen bonds. In the crystal, N—H⋯O hydrogen bonds link the molecules into chains extending parallel to the a axis in which the types of molecules alternate in an …A…B…A…B… fashion.

The asymmetric unit of the title compound, C 22 H 21 N 3 O 2 , consists of two independent molecules (A and B) having differing conformations. The differences mainly concern the dihedral angles which the hydroxyphenyl and dimethylphenyl rings subtend to the central phenylene ring, these being 30.16 (6) and 58.60 (6) in molecule A and 13.42 (7) and 60.31 (7)
The asymmetric unit of the title compound consists of two independent molecules (A and B) having differing conformations. Differences reside mainly in the dihedral angles which the hydroxyphenyl and dimethylphenyl rings make with the central phenylene ring, being 30.16 (6) and 58.60 (6)° in one of the molecules (A) and 13.42 (7) and 60.31 (7)° in the remaining one (B). With the exception of the dimethyphenyl substituent, the conformations of the rest of each molecule are largely determined by intramolecular O-H···N and N-H···O hydrogen bonds ( Fig. 1 and Table 1).
Intermolecular N-H···O hydrogen bonds form chains extending parallel to the a axis ( Fig. 2 and Table 1) where molecules on both types alternate in a.. A···B···A···B.. fashion.

S2. Experimental
A mixture of equimolar ratio of Mefenamic acid hydrazide (1 mmol, 255 mg) and salicaldehyde (1 mmol, 122 mg) with catalytic amount of glacial acetic acid was refluxed for 5 h. On cooling, the precipitate was separated then collected and recrystallized from ethanol to furnish the title compound as brown crystals with m.p= 457-459 K.  The asymmetric unit with labeling scheme and 50% probability ellipsoids. O-H···N and N-H···O hydrogen bonds are

Figure 2
The cell-packing diagram of the title compound viewed down the c axis. Symmetry codes: (a) 1 + x, y, z;  Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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. 0.0329 (7) 0.0369 (7) 0.0293 (7) 0.0049 (6) 0.0040 (6) 0.0006 (6)  0.0300 (7) 0.0306 (7) 0.0352 (7