Redetermination of 2,6-dimethoxy­benzoic acid

Portalone, G.

doi:10.1107/S1600536809001408

Volume 65
Part 2
Pages o327-o328
February 2009

Received 2 January 2009
Accepted 12 January 2009
Online 17 January 2009

Key indicators
Single-crystal X-ray study
T = 298 K
Mean (C-C) = 0.003 Å
R = 0.042
wR = 0.110
Data-to-parameter ratio = 9.7
Details

Redetermination of 2,6-dimethoxybenzoic acid

Gustavo Portalone ^a ^*

^aChemistry Department, "Sapienza" University of Rome, P.le A. Moro, 5, I-00185 Rome, Italy
Correspondence e-mail: g.portalone@caspur.it

The crystal structure of the title compound, C₉H₁₀O₄, was first reported by Swaminathan, Vimala & Lotter [Acta Cryst. (1976), B32, 1897-1900]. It has been re-examined, improving the precision of the derived geometric parameters. The asymmetric unit comprises a non-planar independent molecule, as the methoxy substituents force the carboxy group to be twisted away from the plane of the aromatic ring by 56.12 (9)°. Due to the antiplanar conformation adopted by the OH group, the molecular components do not form the conventional dimeric units, but are associated in the crystal in chains stabilized by linear O-HO hydrogen bonds, involving the OH groups and the carbonyl O atoms, which form C(3) motifs.

Related literature

For previous structure determinations, see: Swaminathan et al. (1976); Bryan & White (1982). For related literature, see: Gopalakrishna & Cartz, 1972; Leiserowitz, 1976; Byriel et al., 1991; Chen et al., 2007. For computation of ring patterns formed by hydrogen bonds in crystal structures, see: Etter et al. (1990); Bernstein et al. (1995); Motherwell et al. (1999). For a description of the Cambridge Structural Database, see: Allen (2002).

Experimental

Crystal data

C₉H₁₀O₄
M_r = 182.17
Orthorhombic, P 2₁ 2₁ 2₁
a = 7.12255 (13) Å
b = 8.92296 (15) Å
c = 13.79430 (18) Å
V = 876.69 (2) Å³
Z = 4
Mo K radiation
= 0.11 mm^-1
T = 298 (2) K
0.12 × 0.10 × 0.10 mm

Data collection

Oxford Diffraction Xcalibur S CCD diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006 $[Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]$ ) T_min = 0.967, T_max = 0.999
234729 measured reflections
1246 independent reflections
1241 reflections with I > 2(I)
R_int = 0.039

Refinement

R[F² > 2(F²)] = 0.042
wR(F²) = 0.110
S = 1.25
1246 reflections
129 parameters
H atoms treated by a mixture of independent and constrained refinement
_max = 0.17 e Å^-3
_min = -0.20 e Å^-3

Table 1
Hydrogen-bond geometry (Å, °)

D-HA	D-H	HA	DA	D-HA
O2-H2O1ⁱ	0.87 (4)	1.82 (4)	2.681 (2)	172 (4)
Symmetry code: (i) $[-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Data collection: CrysAlis CCD (Oxford Diffraction, 2006 $[Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]$ ); cell refinement: CrysAlis RED (Oxford Diffraction, 2006 $[Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.]$ ); data reduction: CrysAlis RED; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: KP2203 ).

Acknowledgements

We thank MIUR (Rome) for 2006 financial support of the project `X-ray diffractometry and spectrometry'.

References

Allen, F. H. (2002). Acta Cryst. B58, 380-388.
Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.
Bryan, R. F. & White, D. H. (1982). Acta Cryst. B38, 1014-1016.
Byriel, K. A., Lynch, D. E., Smith, G. & Kennard, C. H. L. (1991). Aust. J. Chem. 44, 1459-1464.
Chen, Q., Qin, J.-K., Zeng, M.-H. & Ng, S. W. (2007). Acta Cryst. E63, o453-o454.
Etter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46, 256-262.
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.
Gopalakrishna, E. M. & Cartz, L. (1972). Acta Cryst. B28, 2917-2924.
Leiserowitz, L. (1976). Acta Cryst. B32, 775-802.
Motherwell, W. D. S., Shields, G. P. & Allen, F. H. (1999). Acta Cryst. B55, 1044-1056.
Oxford Diffraction (2006). CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Abingdon, England.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Swaminathan, S., Vimala, T. M. & Lotter, H. (1976). Acta Cryst. B32, 1897-1900.

organic compounds