Methyl 4-(3-chloropropoxy)-5-methoxy-2-nitrobenzoate

The asymmetric unit of the title compound, C12H14ClNO6, contains two crystallographically independent molecules, in which the benzene rings are oriented at a dihedral angle of 9.12 (3)°. In the crystal structure, weak intermolecular C—H⋯O hydrogen bonds link the molecules into a three-dimensional network.

The asymmetric unit of the title compound, C 12 H 14 ClNO 6 , contains two crystallographically independent molecules, in which the benzene rings are oriented at a dihedral angle of 9.12 (3) . In the crystal structure, weak intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules into a threedimensional network.
The asymmetric unit of the title compound contains two crystallographically independent molecules (Fig. 1), in which the bond lengths (Allen et al., 1987) and angles are within normal ranges. Rings A (C3-C8) and A′ (C15-C20) are, of course, planar and they are oriented at a dihedral angle of A/A′ = 9.12 (3)°.
In the crystal structure, weak intermolecular C-H···O hydrogen bonds (Table 1) link the molecules into a three dimensional network (Fig. 2), in which they may be effective in the stabilization of the structure.

S2. Experimental
For the preparation of the title compound, a solution of methyl 4-(3-chloro-propoxy)-3-methoxybenzoate (19 mmol) in acetic acid (20 ml) was added dropwise to nitric acid (98%, 4.5 ml) at 273-278 K. The mixture was stirred for 1 h at room temperature, and then for 2 h at 323 K. After the reaction was completed, the reaction mixture was poured into ice/water (130 ml), and then extracted with trichloromethane (20 ml). The combined organic phases were collected, washed with saturated sodium bicarbonate (20 ml), brine (20 ml), dried (Na 2 SO 4 ) and decolorized (charcoal). Trichloromethane was then removed under reduced pressure to give a yellow oil, which was crystallized from ethyl acetate/petroleum ether to afford the product as light yellow crystals (m.p. 337 K). Crystals suitable for X-ray analysis were obtained by slow evaporation of a methanol solution.

S3. 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.  The molecular structure of the title molecule, with the atom-numbering scheme.

Methyl 4-(3-chloropropoxy)-5-methoxy-2-nitrobenzoate
where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.40 e Å −3 Δρ min = −0.30 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.0049 (6) Special details 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 > 2sigma(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.