Ethyl 4-chloro-3-nitrobenzoate

In the molecule of the title compound, C9H8ClNO4, an intramolecular C—H⋯O hydrogen bond results in the formation of a planar five-membered ring, which is nearly coplanar with the adjacent six-membered ring, the rings being oriented at a dihedral angle of 4.40 (3)°. In the crystal structure, intermolecular C—H⋯O hydrogen bonds link the molecules.

In the molecule of the title compound, C 9 H 8 ClNO 4 , an intramolecular C-HÁ Á ÁO hydrogen bond results in the formation of a planar five-membered ring, which is nearly coplanar with the adjacent six-membered ring, the rings being oriented at a dihedral angle of 4.40 (3) . In the crystal structure, intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules.
In the molecule of (I), (Fig. 1) the bond lengths and angles are within normal ranges (Allen et al., 1987). The intramolecular C-H···O hydrogen bond (Table 1) results in the formation of a planar five-membered ring B (C2/H2B/C3/O1/O2). Ring A (C4-C9) is, of course, planar and the dihedral angle between them is A/B = 4.40 (3)°. So, rings A and B are also nearly co-planar.
In the crystal structure, intermolecular C-H···O hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Experimental
For the preparation of the title compound, 4-chloro-3-nitrobenzoic acid (35.0 g, 174 mmol) was suspended in ethanol (150 ml) and cooled to 273 K. Concentrated sulfuric acid (15 ml) was slowly added with stirring, and then the mixture was heated under reflux for 17 h. Upon cooling to room temperature, a precipitate formed, which was collected by filtration and washed with cold ethanol (2 × 50 ml) and hexane (2 × 50 ml) to afford the ethyl ester as a white solid (yield; 29.9 g, 75%) (Daniel et al., 2004). Crystals of (I) suitable for X-ray analysis were obtained by slow evaporation of a methanol solution.

Refinement
H atoms were positioned geometrically, with C-H = 0.93, 0.97 and 0.96 Å for aromatic, methylene and methyl H, respectively, and constrained to ride on their parent atoms, with U iso (H) = xU eq (C), where x = 1.5 for methyl H, and x = 1.2 for all other H atoms. Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.