N-(4-Chloro-3-nitrophenyl)succinamic acid

In the title compound, C10H9ClN2O5, the nitro group is significantly twisted out of the plane of the benzene ring to which it is attached [dihedral angle = 27.4 (6)°]. In the crystal, molecules are linked into centrosymmetric dimers via pairs of O—H⋯O hydrogen bonds. These dimers are further linked by N—H⋯O hydrogen bonds into double chains running along the a axis.

BTG thanks the University Grants Commission, Government of India, New Delhi, for a special grant under UGC-BSR one-time grant to faculty.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT5832).
In the structure, the O-H···O and N-H···O intermolecular hydrogen bonds link the molecules into double chains running along the a axis (Table 1, Fig. 2).

Experimental
Succinic anhydride (0.025 mol) in toluene (25 ml) was treated dropwise with 4-chloro-3-nitroaniline (0.025 mol) also in toluene (20 ml) with constant stirring. The resulting mixture was stirred for about 30 min and set aside for an additional 30 min at room temperature for the completion of reaction. The mixture was then treated with dilute hydrochloric acid to remove the unreacted 4-chloro-3-nitroaniline. The resultant solid N-(4-Chloro-3-nitrophenyl)succinamic acid was filtered under suction and washed thoroughly with water to remove the unreacted succinic anhydride and succinic acid. It was recrystallized to constant melting point from ethanol. The purity of the compound was checked and characterized by its infrared spectra.
Rod like colorless single crystals of the title compound used in X-ray diffraction studies were grown in an ethanol solution by slow evaporation of the solvent (0.5 g in about 30 ml of ethanol) at room temperature.

Refinement
All H atoms were located in a difference map Those bonded to C H atoms were positioned with idealized geometry using a riding model with the aromatic C-H = 0.93 Å and methylene C-H = 0.97 Å. The coordinates of the H atoms bonded to N and O were refined with the N-H and O-H distance restrained to 0.86 (2) Å and 0.82 (2)Å, respectively. All H atoms were refined with isotropic displacement parameters set at 1.2 U eq of the parent atom.  (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figure 1
Molecular structure of the title compound, showing the atom labelling scheme and with displacement ellipsoids drawn at the 50% probability level.

Figure 2
Molecular packing of the title compound with hydrogen bonding shown as dashed lines. 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.