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Acta Cryst. (2009). E65, o335    [ doi:10.1107/S1600536809001093 ]

Methyl 3-carboxy-5-nitrobenzoate

P. Zou, M.-H. Xie, S.-N. Luo, Y.-L. Liu and Y.-J. Shen

Abstract top

The structure of the title compound, C9H7NO6, is essentially planar [maximum deviation 0.284 (2)Å] except for the methyl H atoms. The crystal structure is stabilized by asymmetric O-H...O hydrogen bonds linking the hydrogen carboxylates into pairs around the inversion centres. There is also [pi]-[pi] stacking of the benzene rings [centroid-centroid distance 3.6912 (12) Å].

Comment top

The molecule of the title complex (Fig.1) is useful as an important intermediate for the preparation of iodinated X-ray contrast media, such as iotalamic acid, ioxitalamic acid, and Ioxilan, which are used clinically all over the world (Morin et al., 1987; Singh et al., 1980; Stacul et al., 2001). We report here the crystal structure of title compound. The crystal data show that the bond lengths and angles are within expected ranges. TThe molecule is essentially planar: the maximum deviation from the weighted least-squares plane calculated through all the non-H atoms is 0.284 (2)Å for O2. The molecules are stacked via π-π interactions, with the centroid–centroid distance of 3.6912 (12)Å [symmetry code(i): 2-x, 1-y, 1-z]. The stacked columns are linked together by two intermolecular hydrogen bonds, O—H···O and C—H···O (Tab. 1 and Fig. 2). The O—H···O hydrogen bonds bind the hydrogencarboxylates into pairs.

Related literature top

The title complex is as an important intermediate for the preparation of iodinated X-ray contrast media, see: Morin et al. (1987); Singh & Rathore (1980); Stacul et al. (2001); Jin & Xiao (2005).

Experimental top

Dimethyl 5-nitroisophthalic acid (956 mg, 4 mmol) was dissolved in hot methanol (6 ml), then sodium hydroxide (152 mg, 3.8 mmol) in methanol (2 ml) was added and refluxed for 30 min. Methanol was distilled off. The solid residue was extracted by warm water and the undissolved diester was filtered off. The filtrate was acidified with 1 mol/l hydrochloric acid (4 ml). The precipitate was filtered and washed with cold water. The crude product was purified by recrystallization. Single crystals were grown by slow evaporation of a ethanol/water (v/v 1:1) solution: colourless block-shaped crystals were formed after several days.

Refinement top

All the H atoms could have been discerned in the difference electron density maps. With exception of the hydrogen belonging to the hydroxyl group of the hydrogencarboxylate the hydrogens were situated into the idealized positions and refined in riding motion approximation. The hydroxyl hydrogen was refined freely. The used constraints: Caryl—H = 0.93 Å, Uiso(H) = 1.2Ueq(Caryl); Cmethyl—H = 0.96 Å, Uiso(H) = 1.5Ueq(methyl).

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. A view of the title compound with the atomic numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.
[Figure 2] Fig. 2. A packing diagram viewed along the b axis.
Methyl 3-carboxy-5-nitrobenzoate top
Crystal data top
C9H7NO6F(000) = 464
Mr = 225.16Dx = 1.580 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 25 reflections
a = 7.3450 (15) Åθ = 10–13°
b = 8.9050 (18) ŵ = 0.14 mm−1
c = 14.474 (3) ÅT = 293 K
β = 91.18 (3)°Block, colourless
V = 946.5 (3) Å30.30 × 0.20 × 0.10 mm
Z = 4
Data collection top
Enraf–Nonius CAD-4
diffractometer		1284 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.021
graphiteθmax = 25.3°, θmin = 2.7°
ω/2θ scansh = 0→8
Absorption correction: ψ scan
(North et al., 1968)		k = 0→10
Tmin = 0.950, Tmax = 0.977l = −17→17
1859 measured reflections3 standard reflections every 200 reflections
1717 independent reflections intensity decay: 1.0%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.039Hydrogen site location: difference Fourier map
wR(F2) = 0.105H atoms treated by a mixture of independent and constrained refinement
S = 1.03 w = 1/[σ2(Fo2) + (0.057P)2 + 0.0354P]
where P = (Fo2 + 2Fc2)/3
1717 reflections(Δ/σ)max < 0.001
150 parametersΔρmax = 0.17 e Å−3
0 restraintsΔρmin = −0.13 e Å−3
23 constraints
Crystal data top
C9H7NO6V = 946.5 (3) Å3
Mr = 225.16Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.3450 (15) ŵ = 0.14 mm−1
b = 8.9050 (18) ÅT = 293 K
c = 14.474 (3) Å0.30 × 0.20 × 0.10 mm
β = 91.18 (3)°
Data collection top
Enraf–Nonius CAD-4
diffractometer		1284 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)		Rint = 0.021
Tmin = 0.950, Tmax = 0.977θmax = 25.3°
1859 measured reflections3 standard reflections every 200 reflections
1717 independent reflections intensity decay: 1.0%
Refinement top
R[F2 > 2σ(F2)] = 0.039H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.105Δρmax = 0.17 e Å−3
S = 1.03Δρmin = −0.13 e Å−3
1717 reflectionsAbsolute structure: ?
150 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
N1.0387 (2)0.49976 (17)0.29780 (10)0.0475 (4)
O11.30752 (17)0.20120 (16)0.64959 (9)0.0588 (4)
C11.4451 (3)0.2024 (3)0.72271 (15)0.0742 (7)
H1A1.43270.11420.76020.111*
H1B1.43010.29020.76030.111*
H1C1.56380.20360.69620.111*
C21.3171 (2)0.3110 (2)0.58767 (12)0.0442 (4)
O21.4321 (2)0.40512 (19)0.58894 (10)0.0769 (5)
C31.1649 (2)0.30531 (18)0.51817 (11)0.0375 (4)
O31.1685 (2)0.58281 (18)0.29145 (11)0.0730 (5)
O40.9140 (2)0.4969 (2)0.24169 (11)0.0832 (6)
C41.0120 (2)0.21563 (18)0.53024 (11)0.0382 (4)
H4A1.00530.15330.58160.046*
O50.70372 (17)0.03897 (15)0.54893 (9)0.0561 (4)
C50.8694 (2)0.21906 (18)0.46585 (12)0.0373 (4)
O60.57474 (18)0.13777 (16)0.42237 (9)0.0560 (4)
H6B0.475 (4)0.072 (3)0.4318 (19)0.119 (10)*
C60.8793 (2)0.31082 (18)0.38850 (11)0.0380 (4)
H6A0.78500.31310.34470.046*
C71.0324 (2)0.39840 (18)0.37824 (11)0.0368 (4)
C81.1757 (2)0.39837 (18)0.44108 (11)0.0379 (4)
H8A1.27710.45890.43230.046*
C90.7057 (2)0.12519 (19)0.48049 (12)0.0396 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N0.0515 (9)0.0492 (9)0.0419 (9)−0.0049 (8)−0.0003 (7)0.0054 (7)
O10.0542 (8)0.0634 (9)0.0579 (8)−0.0185 (7)−0.0205 (6)0.0167 (7)
C10.0644 (13)0.1017 (19)0.0555 (13)−0.0228 (13)−0.0249 (11)0.0225 (13)
C20.0414 (9)0.0467 (11)0.0443 (10)−0.0094 (9)−0.0046 (8)0.0030 (8)
O20.0626 (9)0.0911 (12)0.0759 (11)−0.0421 (9)−0.0269 (8)0.0280 (9)
C30.0377 (9)0.0344 (9)0.0404 (9)−0.0030 (7)−0.0009 (7)−0.0046 (7)
O30.0685 (10)0.0765 (10)0.0737 (10)−0.0267 (8)−0.0043 (8)0.0321 (8)
O40.0783 (11)0.1067 (14)0.0635 (10)−0.0288 (10)−0.0274 (8)0.0353 (9)
C40.0408 (9)0.0331 (9)0.0407 (9)−0.0040 (7)−0.0017 (7)−0.0005 (7)
O50.0499 (8)0.0578 (8)0.0601 (8)−0.0174 (6)−0.0112 (6)0.0174 (7)
C50.0369 (8)0.0324 (9)0.0424 (9)−0.0027 (7)−0.0020 (7)−0.0053 (7)
O60.0454 (8)0.0569 (9)0.0650 (9)−0.0201 (7)−0.0184 (7)0.0123 (7)
C60.0396 (9)0.0369 (9)0.0373 (9)−0.0014 (8)−0.0049 (7)−0.0040 (7)
C70.0409 (9)0.0355 (9)0.0342 (8)−0.0027 (7)0.0020 (7)−0.0005 (7)
C80.0332 (8)0.0370 (9)0.0436 (10)−0.0037 (7)0.0034 (7)−0.0050 (8)
C90.0420 (9)0.0330 (9)0.0435 (10)−0.0055 (8)−0.0060 (8)−0.0006 (8)
Geometric parameters (Å, °) top
N—O31.211 (2)C4—C51.388 (2)
N—O41.2122 (19)C4—H4A0.9300
N—C71.475 (2)O5—C91.254 (2)
O1—C21.329 (2)C5—C61.389 (2)
O1—C11.448 (2)C5—C91.483 (2)
C1—H1A0.9600O6—C91.270 (2)
C1—H1B0.9600O6—H6B0.95 (3)
C1—H1C0.9600C6—C71.379 (2)
C2—O21.190 (2)C6—H6A0.9300
C2—C31.489 (2)C7—C81.377 (2)
C3—C41.393 (2)C8—H8A0.9300
C3—C81.393 (2)
O3—N—O4123.18 (16)C3—C4—H4A119.9
O3—N—C7118.11 (15)C4—C5—C6120.19 (15)
O4—N—C7118.71 (15)C4—C5—C9119.62 (15)
C2—O1—C1116.20 (15)C6—C5—C9120.19 (15)
O1—C1—H1A109.5C9—O6—H6B115.3 (17)
O1—C1—H1B109.5C7—C6—C5118.42 (15)
H1A—C1—H1B109.5C7—C6—H6A120.8
O1—C1—H1C109.5C5—C6—H6A120.8
H1A—C1—H1C109.5C8—C7—C6122.86 (15)
H1B—C1—H1C109.5C8—C7—N119.05 (15)
O2—C2—O1123.71 (17)C6—C7—N118.05 (15)
O2—C2—C3123.86 (17)C7—C8—C3118.28 (15)
O1—C2—C3112.41 (15)C7—C8—H8A120.9
C4—C3—C8120.06 (15)C3—C8—H8A120.9
C4—C3—C2122.07 (15)O5—C9—O6123.82 (16)
C8—C3—C2117.81 (15)O5—C9—C5118.73 (15)
C5—C4—C3120.18 (16)O6—C9—C5117.45 (15)
C5—C4—H4A119.9
C1—O1—C2—O21.4 (3)C5—C6—C7—N−177.71 (14)
C1—O1—C2—C3−177.00 (17)O3—N—C7—C8−2.1 (2)
O2—C2—C3—C4−165.32 (18)O4—N—C7—C8178.43 (17)
O1—C2—C3—C413.1 (2)O3—N—C7—C6175.95 (17)
O2—C2—C3—C812.0 (3)O4—N—C7—C6−3.6 (2)
O1—C2—C3—C8−169.58 (15)C6—C7—C8—C30.1 (2)
C8—C3—C4—C5−0.3 (2)N—C7—C8—C3178.04 (14)
C2—C3—C4—C5176.95 (16)C4—C3—C8—C7−0.1 (2)
C3—C4—C5—C60.7 (2)C2—C3—C8—C7−177.46 (15)
C3—C4—C5—C9−178.81 (15)C4—C5—C9—O5−3.4 (2)
C4—C5—C6—C7−0.6 (2)C6—C5—C9—O5177.14 (16)
C9—C5—C6—C7178.84 (15)C4—C5—C9—O6176.41 (16)
C5—C6—C7—C80.2 (2)C6—C5—C9—O6−3.1 (2)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O6—H6B···O5i0.95 (3)1.67 (3)2.6206 (19)177.9 (17)
C8—H8A···O2ii0.932.483.406 (2)174
Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x+3, −y+1, −z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O6—H6B···O5i0.95 (3)1.67 (3)2.6206 (19)177.9 (17)
C8—H8A···O2ii0.932.483.406 (2)174
Symmetry codes: (i) −x+1, −y, −z+1; (ii) −x+3, −y+1, −z+1.
Acknowledgements top

The authors acknowledge financial support from Jiangsu Institute of Nuclear Medicine.

references
References top

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