Crystal structure of 3-acet­oxy-2-methyl­benzoic acid

Matheswaran Saranya; Annamalai Subashini; Chidambaram Arunagiri; Packianathan Thomas Muthiah

doi:10.1107/S2056989015010865

. 2015 Jun 13;71(Pt 7):o474. doi: 10.1107/S2056989015010865

Crystal structure of 3-acetoxy-2-methylbenzoic acid

Matheswaran Saranya ^a, Annamalai Subashini ^a,^*, Chidambaram Arunagiri ^b, Packianathan Thomas Muthiah ^c

PMCID: PMC4518910 PMID: 26279915

Abstract

In the title molecule, C₁₀H₁₀O₄, the carboxylic acid group is twisted by 11.37 (15)° from the plane of the benzene ring and the acetoxy group is twisted from this plane by 86.60 (17)°. In the crystal, molecules are linked by pairs of O—H⋯O hydrogen bonds, forming inversion dimers with the expected R ₂ ²(8) graph-set motif.

Keywords: crystal structure, ester, acetoxy, benzoic acid, hydrogen bonding, graph-set motifs

Related literature

For related structures, see: Chiari et al. (1981 ▸); Fronczek et al. (1982 ▸); Montis & Hursthouse (2012 ▸); Shoaib et al. (2014 ▸); Wheatley (1964 ▸). graphic file with name e-71-0o474-scheme1.jpg

Experimental

Crystal data

C₁₀H₁₀O₄
M _r = 194.18
Orthorhombic,
a = 7.754 (2) Å
b = 11.346 (3) Å
c = 21.187 (6) Å
V = 1864.0 (9) Å³
Z = 8
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 293 K
0.38 × 0.22 × 0.06 mm

Data collection

Bruker SMART APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▸) T _min = 0.960, T _max = 0.994
14775 measured reflections
2131 independent reflections
1017 reflections with I > 2σ(I)
R _int = 0.095

Refinement

R[F ² > 2σ(F ²)] = 0.063
wR(F ²) = 0.184
S = 1.03
2131 reflections
133 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▸); cell refinement: SAINT (Bruker, 2009 ▸); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: PLATON (Spek, 2009 ▸); software used to prepare material for publication: PLATON.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989015010865/lh5765sup1.cif

e-71-0o474-sup1.cif^{(17.3KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015010865/lh5765Isup2.hkl

e-71-0o474-Isup2.hkl^{(102.7KB, hkl)}

Click here for additional data file.^{(3.8KB, cml)}

Supporting information file. DOI: 10.1107/S2056989015010865/lh5765Isup3.cml

Click here for additional data file.^{(1.1MB, tif)}

. DOI: 10.1107/S2056989015010865/lh5765fig1.tif

The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level.

Click here for additional data file.^{(2.2MB, tif)}

x y z . DOI: 10.1107/S2056989015010865/lh5765fig2.tif

Part of the crystal structure with hydrogen bonds shown as dashed lines [symmetry code: (i) −x, −y + 2, −z + 1].

CCDC reference: 1405114

Additional supporting information: crystallographic information; 3D view; checkCIF report

Enhanced figure: interactive version of Fig. 1

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
O1H1O2ⁱ	0.93(5)	1.70(5)	2.622(3)	176(3)

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Symmetry code: (i) Inline graphic .

Acknowledgments

MS thanks Collegiate Education Chennai, Tamil Nadu, for financial support (College Research Student Fellowship Ref· No. 28696/K2/12).

supplementary crystallographic information

S1. Comment

Crystal structures of 2-acetoxy-3-methylbenzoic acid (3-methyl aspirin) (Chiari et al., 1981) and 2-acetoxy-6-methylbenzoic acid (6-methyl aspirin) have already been reported in the literature (Fronczek et al. 1982). Aspirin is a unique drug as it is effective against pain, it has anti-pyretic and anti-inflammatory properties, and it is widely used during heart attacks or strokes. The crystal and molecular structure of aspirin has been reported by Wheatley in 1964. We report herein on the crystal structure of the title molecule.

The molecular structure of the title compound is shown in Fig. 1. There are some very definite angular distortions within the molecule, both in the benzene ring and the carboxyl group, but more particularly, in the acetyl group. The internal angle at C3 (123.6 (3)°) is greater than 120° (the expected value in terms of hybridization principles), and that at C2 is less (116.2 (2)°). The carboxyl group is bent away from the methyl and acetyl group, possibly by repulsion between O1 and O2, so that there is a substantial increase in the angle C2—C1—C7, and a decrease in C6—C1—C7. The angle O1—C7—O2 is greater than 120°, again suggesting repulsion between oxygen atoms. The carboxyl group is twisted by 11.37 (15)° out of the plane of the benzene ring, and the acetoxy group is twisted out of plane by 86.60 (17)°.

Certain torsion angles reveal conformational changes in the carboxyl and acetoxy groups caused by methyl substitution at C2. Atoms C7 and C8 lie in the plane of the benzene ring and O3 is slightly out of plane. The deviations of atoms C7, C8 and O3 from the least-squares plane of the benzene ring are -0.015 (3), 0.010 (3) and 0.111 (2) Å, respectively.

A similar situation is exists in 2-acetoxy-6-methyl benzoic acid (Fronczek et al. 1982). Comparison of the C2—C3—O3—C9 angle (94.8 (3)°) reveals that the acetoxy group is skewed slightly away from the methyl group in this structure. There is also a slight but significant twist in the ester backbone, C3—O3—C9—C10 = -178.3 (3)°, present in the title compound, a result quite similar to that in 6-methyl aspirin (Fronczek et al. 1982). In the crystal, pairs of O—H···O hydrogen bonds form inversion dimers with the expected R²₂(8) graph-set motif (Fig. 2). The carboxyl oxygen atom O1 acts as a donor in an intermolecular hydrogen bond to atom O2, producing an R²₂(8) ring, thus creating a hydrogen-bonded dimer. This type of motif is commonly observed (Shoaib et al., 2014; Montis & Hursthouse et al., 2012).

S2. Experimental

A hot methanol solution (20 ml) of 3-acetoxy-2-methyl benzoic acid [3 A2MBA] (1 mm 0.194 g, Alfa aesar) was stirred at room temperature for 20 minutes. The resulting solution was kept as such for crystallization. After a few days colourless block-shaped crystals were appeared from the mother liquor.