4-Chloro-N′-[(E)-2-chlorobenzylidene]benzohydrazide monohydrate

The title compound, C14H10Cl2N2O·H2O, has a nearly planar extended conformation [C—N—N—C = −173.66 (15)°]. The dihedral angle between the aromatic rings is 4.6 (2)°. The water molecules alternate with benzohydrazide molecules in chains formed by O—H⋯O hydrogen bonds which run parallel to the a axis. These chains are linked to neighboring chains through N—H⋯O and C—H⋯O interactions, forming a layer parallel to (001).

The title compound, C 14 H 10 Cl 2 N 2 OÁH 2 O, has a nearly planar extended conformation [C-N-N-C = À173.66 (15) ]. The dihedral angle between the aromatic rings is 4.6 (2) . The water molecules alternate with benzohydrazide molecules in chains formed by O-HÁ Á ÁO hydrogen bonds which run parallel to the a axis. These chains are linked to neighboring chains through N-HÁ Á ÁO and C-HÁ Á ÁO interactions, forming a layer parallel to (001).

Comment
Use of non-steroidal anti-inflammatory drugs (NSAIDs) in treatment of pain and inflammation is usually associated with undesirable side effect such as gastrointestinal toxins and ulceration. Recently arylhydrazone scaffold compounds have showed safer profiles of activity and enhanced efficacy in the battle of pain in inflammatory diseases (Koopaei et al., 2013). They have been depicted as dual COX/5-LO inhibitors (Almasirad et al., 2005;Almasirad et al., 2006). In this context and as part of our on-going study in the synthesis of safe profiles of anti-inflammatory pro-drugs we report the synthesis and crystal structure of the title compound.
The title compound (I) in Fig. 1 is in the "extended" conformation with the ring C1-C6 making a dihedral angle of 15.3 (1)° with the mean plane of the C1/C7/N1/O1 unit while the ring C9-C14 makes a dihedral angle of 4.6 (2)° with the plane of the C8/C9/N2 unit. The bond lengths and angles of (I) are normal and comparable with those observed for a similar compound (Cao, 2009).
The lattice water molecules alternate with molecules of (I) in chains formed by O2-H2A(or B)···O1 hydrogen bonds (Table 1 and Fig. 2) which run parallel to the a axis. These chains are linked to neighboring chains through N1-H1···O2 and C8-H8···O2 interactions. In these, the mean plane of the benzohydrazide molecule is inclined approximately 48° to (110).

Experimental
The compound was prepared by refluxing a mixture of 4-chlorobenzohydrazide (1 mmol, 171 mg)) with 2-chlorobenzaldehyde (1 mmol, 141 mg) in ethanol (30 mL) for 5h in the presence of a catalytic amount of glacial acetic acid.
The mixture was cooled and the precipitate was filtered off, dried and recrystallized from ethanol to give pale brown crystals of poor quality. Slow evaporation of an aqueous ethanolic solution of the product afforded colorless block-like crystals of sufficient quality for x-ray diffraction. M. p. 452 454 K    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.