N-(4-Hydroxyphenyl)-4-nitrobenzamide

The molecular structure of the title compound, C13H10N2O4, shows an almost planar conformation as the benzene rings make a dihedral angle of 2.31 (7)°. The nitro group lies in plane with the benzamide ring, with a C—C—N—O torsion angle of 0.6 (2)°. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link molecules into sheets stacked along [10-1].

The molecular structure of the title compound, C 13 H 10 N 2 O 4 , shows an almost planar conformation as the benzene rings make a dihedral angle of 2.31 (7) . The nitro group lies in plane with the benzamide ring, with a C-C-N-O torsion angle of 0.6 (2) . In the crystal, N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds link molecules into sheets stacked along [101].

Related literature
For background to aromatic polyimides, see: Sheng et al. (2009). For the solubilizing role of ether and amide groups in polyimides, see: Litvinov et al. (2010). For a related structure, see: Raza et al. (2010).
Fairly high thermooxidative and outstanding thermal stability, exceptional mechanical and electrical properties and upright chemical resistance are some distinctions of aromatic polyimides that make them documented as high performance polymeric materials (Sheng et al., 2009). The reported title compound, (I), containing ether and amide groups, serve multiple purposes, such as a boost in solubility and upsurge thermal stability of the resulting polyimide (Litvinov et al., 2010). In this connection, the title compound was investigated.

Experimental
Reagent grade quality chemicals were used in this preparation. 4-Aminophenol (0.94 g, 8.6 mmol) in dry dichloromethane (30 ml), a few drops of N, N-dimethylformamide (DMF) and triethylamine (1.25 ml, 8.6 mmol) were placed in a 100 ml, three necked, round bottomed flask, equipped with a condenser, a nitrogen gas inlet tube, a thermometer and a magnetic stirrer. The mixture was stirred at 273-278 K for 30-45 minutes. A solution of 4-nitrobenzoyl chloride (1.59 g, 8.6 mmol) in dichloromethane (20 ml) was added drop-wise via a dropping funnel along with continuous stirring. The reaction mixture was then refluxed for 45 minutes. The flask contents were cooled to room temperature, poured into water and let to stand for 24 h. The resulting bright-yellow precipitate was filtered, washed with hot water and 5% NaOH solution. Finally, product was washed with hot water and dried under vacuum at 350 K. The crude product was recrystallized from ethanol and dichloromethane (2:1, v/v). Yield: 91%; m.p. 406-407 K.

Refinement
Hydrogen atoms were clearly identified in difference syntheses, refined at idealized positions riding on the parent atoms with C-H 0.95, N-H 0.88 and O-H 0.84 Å, and with U ĩso (H) = 1.2U eq (C,N,O)

Figure 2
Crystal packing viewed along c axis with hydrogen bonds as dotted lines. H-atoms not involved are omitted. 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.