Ethyl 4-(2-hydroxyethylamino)-3-nitrobenzoate

In the title compound, C11H14N2O5, the molecular structure is stabilized by an intramolecular N—H⋯O hydrogen bond, which generates an S(6) ring motif. The nitro group is twisted slightly from the attached benzene ring, forming a dihedral angle of 5.2 (2)°. In the crystal packing, intermolecular O—H⋯O and C—H⋯O hydrogen bonds link the molecules into a three-dimensional network. The crystal studied was a non-merohedral twin, the refined ratio of the twin components being 0.264 (2):0.736 (2).

In the title compound, C 11 H 14 N 2 O 5 , the molecular structure is stabilized by an intramolecular N-HÁ Á ÁO hydrogen bond, which generates an S(6) ring motif. The nitro group is twisted slightly from the attached benzene ring, forming a dihedral angle of 5.2 (2) . In the crystal packing, intermolecular O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds link the molecules into a three-dimensional network. The crystal studied was a nonmerohedral twin, the refined ratio of the twin components being 0.264 (2):0.736 (2).

Comment
Benzimidazoles serve as a common scaffold used worldwide for various successful drugs (Mayer et al., 1998). Construction of pharmacologically important benzimidazoles could be accessed via nitrobenzoic acid precursors (Brouillette et al., 1999;Williams et al., 1995;Wright, 1951). The title compound was obtained as an intermediate in the synthesis of benzimidazole derivatives; we present here its crystal structure.
In the title compound ( Fig. 1), the molecular structure is stabilized by an intramolecular N2-H2A···O2 hydrogen bond which generates an S(6) ring motif (Bernstein et al., 1995). The nitro group is slightly twisted away from the benzene ring, the dihedral angle between N1/O1/O2/C2 and C1-C6 being 5.2 (2)°. The bond lengths (Allen et al., 1987) and angles in the molecule are within normal ranges and are similiar to those in other related structures (Narendra Babu, Abdul Rahim, Abd Hamid et al., 2009;Narendra Babu, Abdul Rahim, Osman et al., 2009).

Experimental
The synthesis of the title compound was performed by the dropwise addition of N,N-diisopropyl ethylamine (1.1 mmol) to a stirred solution of ethyl 4-fluoro-3-nitrobenzoate (1.0 mmol) in dry dichloromethane (10.0 ml), followed by ethanolamine (1.1 mmol). The reaction mixture was left stirring overnight at room temperature under an inert atmosphere. Upon completion, the reaction mixture was washed with 10% Na 2 CO 3 (3 x 10.0 ml). The combined organic fractions were dried over MgSO 4 and evaporated in vacuo. Recrystallisation with hot hexane gave the title compound as bright yellow crystals, which were found to be suitable for characterisation by X-ray crystallography.

Refinement
H2A and H5B were located in a difference Fourier map and were refined freely The remaining H atoms were positioned geometrically [C-H = 0.93 to 0.97 Å] and were refined using a riding model, with U iso (H) = xU eq (C), where x = 1.5 for methyl H and 1.2 for all other H atoms. A rotating group model was applied to the methyl group. The crystal studied was a non-merohedral twin, the refined ratio of the twin components being 0.264 (2):0.736 (2). Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme. Hydrogen atoms are shown as spheres of arbitrary radius. The dashed line indicates an intramolecular hydrogen bond.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
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.