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Acta Crystallogr Sect E Struct Rep Online. 2009 November 1; 65(Pt 11): o2819.
Published online 2009 October 23. doi:  10.1107/S1600536809042627
PMCID: PMC2971392

2-Methyl-3,5-dinitro­benzoic acid

Abstract

In the title compound, C8H6N2O6, the O atoms of the nitro groups, the methyl H atoms and the carboxyl C=O and C—OH groups are disordered over two sets of sites with an occupancy ratio of 0.595 (16):0.405 (16). In the crystal, inversion dimers linked by pairs of O—H(...)O hydrogen bonds arise for both carboxyl disorder components and C—H(...)O bonds and weak C—H(...)π inter­actions consolidate the packing.

Related literature

For general background to isocoumarins, see: Hill (1986 [triangle]); Varanda et al. (2004 [triangle]). For related structures, see: Prince et al. (1991 [triangle]); Sarma & Nagaraju (2000 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o2819-scheme1.jpg

Experimental

Crystal data

  • C8H6N2O6
  • M r = 226.15
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o2819-efi1.jpg
  • a = 26.8441 (16) Å
  • b = 5.1044 (3) Å
  • c = 13.8853 (10) Å
  • β = 104.544 (3)°
  • V = 1841.6 (2) Å3
  • Z = 8
  • Mo Kα radiation
  • μ = 0.14 mm−1
  • T = 296 K
  • 0.28 × 0.09 × 0.08 mm

Data collection

  • Bruker Kappa APEXII CCD diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2005 [triangle]) T min = 0.985, T max = 0.987
  • 8618 measured reflections
  • 2019 independent reflections
  • 1626 reflections with I > 2σ(I)
  • R int = 0.025

Refinement

  • R[F 2 > 2σ(F 2)] = 0.035
  • wR(F 2) = 0.098
  • S = 1.07
  • 2019 reflections
  • 189 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.22 e Å−3
  • Δρmin = −0.17 e Å−3

Data collection: APEX2 (Bruker, 2007 [triangle]); cell refinement: SAINT (Bruker, 2007 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]) and PLATON (Spek, 2009 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]) and PLATON.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809042627/hb5136sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809042627/hb5136Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

Isocoumarins are secondary metabolites, derived from acetate pathway, which are structurally related to coumarins but with inverted lactone ring. Isocoumarins shows a wide range of applications and biological activities including anti-cancer (Varanda et al., 2004), anti-tumor (Hill et al., 1986) etc.

The title compound (I, Fig. 1) is an intermediate towards the synthesis of substituted homophthallic acid that is a precursor for the synthesis of isocoumarins.

The ctystal structures of (II) 2,4-Dinitrotoluene (Sarma & Nagaraju 2000), (III) 3,5-Dinitrobenzoic acid (Prince et al., 1991) have been reported. The title compound contains both of these moieties.

The O-atoms of nito groups are disordered over two sets of sites with occupancy ratio of 0.595 (16):0.405 (16). Due to this disorder the H-atoms of CH3 and OH groups are also disordered with same occupancy ratio. The title compound consist of conventional carboxylate dimers (Fig. 2). The benzene ring A (C1–C6) and carboxyl group B (O1/C7/O2) are oriented at a dihedral angle of 23.82 (15)°. The disordered nitro groups C (O3A/N1/O4A), D (O3B/N1/O4B), E (O5A/N2/O6A) and F (O5B/N1/O6B) are certainly planar. The values of dihedral angles for C/E and D/F are 57 (1) and 76 (1)°, respectively. The molecules are stabilized due to H-bondings and C—H···π interactions (Table 1).

Experimental

HNO3 (28.0 g, 0.7 mol) was added as drops to an ice-chilled (273 K) solution of o-toluic acid (13.6 g, 0.1 mol) in H2SO4 (110.4 g, 11.2 mol) with constant stirring. The reaction mixture was stirred for 15 minutes, left overnight on stirring at room temperature and then refluxed at 373 K for 4 h. More HNO3 (21.0 g, 0.69 mol) was added after cooling to room temperature and refluxed for further 3 h. The reaction mixture was cooled to room temperature and poured to ice. The precipitates were filtered, washed with distilled water to remove free sulfates and nitrates. Recrystallization from methanol/water (1:1) afforded yellow needles of (I) suitable for x-ray diffraction. Yield 92%.

Refinement

The O-atoms of NO2 groups along with H-atoms of CH3 and OH groups are disordered. The coordinates of H-atoms of hydroxy group were refined.

H-atoms were positioned geometrically, with C—H = 0.93 and 0.96 Å for aryl and methyl H, respectively and constrained to ride on their parent atoms, with Uiso(H) = xUeq(C, O), where x = 1.5 for methyl and 1.2 for all other H atoms.

Figures

Fig. 1.
View of (I) with the atom numbering scheme having atoms of greater occupancy ratio. The displacement ellipsoids are drawn at the 30% probability level. H-atoms are shown by small circles of arbitrary radii.
Fig. 2.
View of (I) with the atom numbering scheme having atoms of smaller occupancy ratio. The displacement ellipsoids are drawn at the 30% probability level. H-atoms are shown by small circles of arbitrary radii.
Fig. 3.
The partial packing of (I), which shows that molecules form inversion dimers.

Crystal data

C8H6N2O6F(000) = 928
Mr = 226.15Dx = 1.631 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 2019 reflections
a = 26.8441 (16) Åθ = 3.0–27.1°
b = 5.1044 (3) ŵ = 0.14 mm1
c = 13.8853 (10) ÅT = 296 K
β = 104.544 (3)°Needle, yellow
V = 1841.6 (2) Å30.28 × 0.09 × 0.08 mm
Z = 8

Data collection

Bruker Kappa APEXII CCD diffractometer2019 independent reflections
Radiation source: fine-focus sealed tube1626 reflections with I > 2σ(I)
graphiteRint = 0.025
Detector resolution: 7.60 pixels mm-1θmax = 27.1°, θmin = 3.0°
ω scansh = −34→21
Absorption correction: multi-scan (SADABS; Bruker, 2005)k = −6→6
Tmin = 0.985, Tmax = 0.987l = −16→17
8618 measured reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.035Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.098H atoms treated by a mixture of independent and constrained refinement
S = 1.07w = 1/[σ2(Fo2) + (0.0466P)2 + 0.7672P] where P = (Fo2 + 2Fc2)/3
2019 reflections(Δ/σ)max < 0.001
189 parametersΔρmax = 0.22 e Å3
0 restraintsΔρmin = −0.17 e Å3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles
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)

xyzUiso*/UeqOcc. (<1)
O10.01701 (4)0.2581 (2)0.43564 (8)0.0512 (3)
O20.05404 (4)−0.13177 (19)0.47311 (8)0.0478 (3)
O3A0.2288 (4)−0.200 (2)0.3383 (8)0.083 (2)0.595 (16)
O4A0.2604 (2)0.1735 (16)0.3731 (8)0.0879 (18)0.595 (16)
O5A0.1204 (4)0.696 (2)0.1252 (9)0.082 (3)0.595 (16)
O6A0.0510 (4)0.781 (2)0.1802 (7)0.0573 (14)0.595 (16)
N10.22362 (4)0.0323 (3)0.35244 (10)0.0497 (4)
N20.09302 (5)0.6426 (3)0.17734 (9)0.0485 (4)
C10.09152 (4)0.1704 (2)0.38137 (9)0.0325 (3)
C20.14060 (4)0.0536 (2)0.39970 (9)0.0335 (3)
C30.17128 (4)0.1421 (3)0.33837 (10)0.0367 (4)
C40.15720 (5)0.3269 (3)0.26482 (10)0.0399 (4)
C50.10921 (5)0.4375 (3)0.25252 (9)0.0371 (4)
C60.07666 (4)0.3649 (3)0.31037 (9)0.0360 (4)
C70.05193 (4)0.0909 (3)0.43530 (9)0.0346 (4)
C80.16097 (5)−0.1411 (3)0.48095 (11)0.0448 (4)
O4B0.2566 (3)0.149 (3)0.4132 (8)0.084 (3)0.405 (16)
O5B0.0598 (5)0.750 (3)0.1754 (11)0.061 (2)0.405 (16)
O6B0.1179 (7)0.655 (3)0.1105 (11)0.061 (2)0.405 (16)
O3B0.2269 (6)−0.152 (3)0.3038 (13)0.094 (4)0.405 (16)
H8B0.15619−0.074880.542720.0672*0.595 (16)
H8C0.19697−0.169350.486910.0672*0.595 (16)
H8A0.14278−0.303730.465220.0672*0.595 (16)
H1−0.0046 (14)0.209 (6)0.465 (2)0.0614*0.595 (16)
H40.178960.375040.225250.0479*
H60.044840.446120.301770.0432*
H20.0315 (19)−0.169 (9)0.498 (4)0.0614*0.405 (16)
H8D0.19134−0.071890.525750.0672*0.405 (16)
H8E0.16930−0.301480.452420.0672*0.405 (16)
H8F0.13531−0.174590.516690.0672*0.405 (16)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0444 (5)0.0495 (6)0.0706 (7)0.0066 (4)0.0349 (5)0.0127 (5)
O20.0450 (5)0.0407 (5)0.0658 (7)−0.0019 (4)0.0293 (5)0.0092 (5)
O3A0.058 (2)0.064 (3)0.121 (5)0.0211 (19)0.012 (3)−0.014 (3)
O4A0.0343 (13)0.091 (2)0.142 (5)−0.0100 (13)0.029 (3)−0.005 (3)
O5A0.068 (3)0.114 (5)0.071 (5)−0.004 (3)0.031 (3)0.051 (4)
O6A0.052 (3)0.060 (2)0.061 (2)0.027 (2)0.016 (2)0.0131 (16)
N10.0356 (6)0.0591 (8)0.0593 (8)0.0035 (6)0.0213 (6)0.0073 (7)
N20.0488 (7)0.0541 (7)0.0416 (7)−0.0018 (6)0.0093 (6)0.0104 (6)
C10.0303 (6)0.0364 (6)0.0325 (6)−0.0048 (5)0.0109 (5)−0.0019 (5)
C20.0315 (6)0.0354 (6)0.0345 (6)−0.0036 (5)0.0100 (5)−0.0024 (5)
C30.0295 (6)0.0424 (7)0.0401 (7)−0.0005 (5)0.0124 (5)−0.0016 (6)
C40.0364 (6)0.0489 (8)0.0388 (7)−0.0063 (6)0.0175 (5)0.0012 (6)
C50.0374 (6)0.0421 (7)0.0320 (6)−0.0034 (5)0.0089 (5)0.0039 (5)
C60.0300 (6)0.0414 (7)0.0368 (7)−0.0013 (5)0.0090 (5)−0.0003 (5)
C70.0316 (6)0.0369 (6)0.0376 (7)−0.0031 (5)0.0128 (5)−0.0007 (5)
C80.0416 (7)0.0468 (8)0.0466 (8)0.0033 (6)0.0124 (6)0.0089 (6)
O4B0.029 (3)0.115 (5)0.102 (5)0.000 (3)0.005 (3)−0.011 (4)
O5B0.064 (5)0.068 (4)0.064 (3)0.046 (3)0.039 (3)0.032 (3)
O6B0.075 (5)0.075 (3)0.040 (2)0.020 (3)0.027 (2)0.017 (2)
O3B0.070 (5)0.074 (6)0.152 (10)0.020 (3)0.053 (6)−0.025 (6)

Geometric parameters (Å, °)

O1—C71.2686 (17)C1—C61.3854 (18)
O2—C71.2473 (18)C1—C71.5015 (16)
O3A—N11.216 (10)C2—C31.3999 (17)
O3B—N11.174 (16)C2—C81.4999 (19)
O4A—N11.198 (7)C3—C41.372 (2)
O4B—N11.215 (12)C4—C51.377 (2)
O5A—N21.186 (12)C5—C61.3779 (18)
O5B—N21.041 (14)C4—H40.9300
O6A—N21.340 (11)C6—H60.9300
O6B—N21.274 (17)C8—H8A0.9600
O1—H10.83 (4)C8—H8B0.9600
O2—H20.79 (5)C8—H8C0.9600
N1—C31.4794 (17)C8—H8D0.9600
N2—C51.465 (2)C8—H8E0.9600
C1—C21.4098 (16)C8—H8F0.9600
C7—O1—H1114 (2)C4—C5—C6121.86 (13)
C7—O2—H2116 (3)N2—C5—C4118.82 (12)
O4A—N1—C3120.1 (4)N2—C5—C6119.31 (12)
O3B—N1—C3115.7 (8)C1—C6—C5119.75 (11)
O3A—N1—C3119.5 (5)O2—C7—C1119.55 (11)
O3B—N1—O4B130.2 (10)O1—C7—O2124.54 (12)
O4B—N1—C3114.1 (6)O1—C7—C1115.86 (12)
O3A—N1—O4A120.3 (6)C3—C4—H4122.00
O5A—N2—O6A123.5 (7)C5—C4—H4122.00
O5B—N2—C5119.6 (8)C1—C6—H6120.00
O6B—N2—C5116.0 (7)C5—C6—H6120.00
O5B—N2—O6B123.9 (11)C2—C8—H8A109.00
O6A—N2—C5117.2 (4)C2—C8—H8B109.00
O5A—N2—C5118.7 (5)C2—C8—H8C109.00
C2—C1—C7122.82 (10)C2—C8—H8D109.00
C2—C1—C6121.37 (10)C2—C8—H8E109.00
C6—C1—C7115.80 (10)C2—C8—H8F109.00
C3—C2—C8120.82 (11)H8A—C8—H8B109.00
C1—C2—C8124.31 (11)H8A—C8—H8C109.00
C1—C2—C3114.81 (11)H8B—C8—H8C109.00
N1—C3—C2118.80 (12)H8D—C8—H8E109.00
N1—C3—C4115.71 (12)H8D—C8—H8F109.00
C2—C3—C4125.49 (12)H8E—C8—H8F109.00
C3—C4—C5116.64 (12)
O3A—N1—C3—C263.2 (6)C2—C1—C7—O1158.86 (11)
O3A—N1—C3—C4−117.2 (6)C2—C1—C7—O2−23.53 (18)
O4A—N1—C3—C2−120.3 (6)C6—C1—C7—O1−22.16 (17)
O4A—N1—C3—C459.4 (6)C6—C1—C7—O2155.46 (12)
O5A—N2—C5—C44.6 (6)C1—C2—C3—N1179.58 (12)
O5A—N2—C5—C6−176.9 (6)C1—C2—C3—C4−0.1 (2)
O6A—N2—C5—C4−167.3 (5)C8—C2—C3—N12.39 (19)
O6A—N2—C5—C611.2 (5)C8—C2—C3—C4−177.24 (14)
C6—C1—C2—C3−2.47 (17)N1—C3—C4—C5−178.07 (13)
C6—C1—C2—C8174.61 (12)C2—C3—C4—C51.6 (2)
C7—C1—C2—C3176.46 (12)C3—C4—C5—N2177.87 (13)
C7—C1—C2—C8−6.46 (18)C3—C4—C5—C6−0.6 (2)
C2—C1—C6—C53.43 (19)N2—C5—C6—C1179.73 (12)
C7—C1—C6—C5−175.58 (12)C4—C5—C6—C1−1.8 (2)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1—H1···O2i0.83 (4)1.80 (4)2.6216 (16)175 (3)
C8—H8B···O5Aii0.962.553.385 (11)145
C8—H8C···O3A0.962.433.023 (11)120
C8—H8A···Cg1iii0.962.963.781 (2)144
C8—H8E···Cg1iii0.962.963.781 (2)144

Symmetry codes: (i) −x, −y, −z+1; (ii) x, −y+1, z+1/2; (iii) x, y−1, z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB5136).

References

  • Bruker (2005). SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Bruker (2007). APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Hill, R. A. (1986). Chem. Org. Naturst. Fortschr 49, 1–78.
  • Prince, P., Fronczek, F. R. & Gandour, R. D. (1991). Acta Cryst. C47, 895–898.
  • Sarma, J. A. R. P. & Nagaraju, A. (2000). J. Chem. Soc. Perkin Trans. 2, pp. 1113–1118.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]
  • Varanda, E. A., Devienne, K. F., Raddi, M. S. G., Furuya, E. M. & Vilegas, W. (2004). Toxicol. in Vitro, 18, 109–114. [PubMed]

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