2-[(2-Acet­oxy­benzo­yl)­oxy]benzoic acid

Katarzyna A Solanko; Andrew D Bond

doi:10.1107/S1600536812026475

. 2012 Jun 16;68(Pt 7):o2108. doi: 10.1107/S1600536812026475

2-[(2-Acetoxybenzoyl)oxy]benzoic acid

Katarzyna A Solanko ^a, Andrew D Bond ^a,^*

PMCID: PMC3393920 PMID: 22798785

Abstract

The title compound, C₁₆H₁₂O₆, is a common impurity of ortho-acetylsalicylic acid (aspirin). The benzene rings form a dihedral angle of 81.9 (1)° while the acetyl and carboxyl groups form dihedral angles of 74.0 (1) and 26.4 (2)°, respectively, with the benzene rings to which they are bound. In the crystal, molecules are linked by pairs of O—H⋯O hydrogen bonds between the carboxyl groups, forming inversion dimers.

Related literature

For background literature concerning the crystallization and crystal structure of aspirin, see: Bond et al. (2007 ▶, 2011 ▶). For a discussion of the pharmacological effects of acetylsalicylsalicylic acid, see: Bundgaard (1974 ▶). For related structures, see: Greener et al. (2000 ▶); Cox et al. (2000 ▶); Iqbal et al. (2007 ▶).

Experimental

Crystal data

C₁₆H₁₂O₆
M _r = 300.26
Monoclinic,
a = 9.6314 (5) Å
b = 7.7548 (3) Å
c = 18.0763 (8) Å
β = 95.572 (2)°
V = 1343.73 (11) Å³
Z = 4
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 150 K
0.40 × 0.20 × 0.02 mm

Data collection

Bruker Nonius X8 APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ▶) T _min = 0.887, T _max = 0.998
15807 measured reflections
2367 independent reflections
1868 reflections with I > 2σ(I)
R _int = 0.031

Refinement

R[F ² > 2σ(F ²)] = 0.033
wR(F ²) = 0.080
S = 1.04
2367 reflections
204 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.18 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: APEX2 (Bruker, 2010 ▶); cell refinement: SAINT (Bruker, 2010 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812026475/fy2058sup1.cif

e-68-o2108-sup1.cif^{(22.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812026475/fy2058Isup2.hkl

e-68-o2108-Isup2.hkl^{(116.3KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812026475/fy2058Isup3.cml

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5—H5⋯O6ⁱ	0.86 (1)	1.81 (1)	2.6660 (16)	176 (2)

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Symmetry code: (i) Inline graphic .

Acknowledgments

We are grateful to the Danish Natural Science Research Council and the Carlsberg Foundation for provision of the X-ray equipment.

supplementary crystallographic information

Comment

Acetylsalicylsalicylic acid is a condensation (dehydration) product of acetylsalicylic acid (aspirin) and salicylic acid, and is a common impurity in commerical aspirin samples. Its pharmacological effects have been examined by Bundgaard (1974), and it has been suggested that the compound is a potentially immunogenic substance involved in the development of allergic reactions to aspirin.

Experimental

The compound was prepared by acetylation of salicylsalicylic acid (purchased from Alfa Aesar) using acetic anhydride. 0.02 mol of salicylsalicylic acid was mixed with 0.01 mol of acetic anhydride with addition of 10% NaOH (5 ml) and ca 50 ml ice. The reactants were stirred for ca 2 h and the reaction was monitored by thin-layer chromotography. When the reaction was complete, the white solid was filtered and recrystallized from ethanol (yield 90%).