2-[(2-Acet-oxy-benzo-yl)-oxy]benzoic acid.

The title compound, C(16)H(12)O(6), is a common impurity of ortho-acetyl-salicylic 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, mol-ecules 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 = 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

Δρmax = 0.18 e Å−3

Δρmin = −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.

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

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

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

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

C16H12O6	F(000) = 624
Mr = 300.26	Dx = 1.484 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5582 reflections
a = 9.6314 (5) Å	θ = 2.9–25.0°
b = 7.7548 (3) Å	µ = 0.12 mm−1
c = 18.0763 (8) Å	T = 150 K
β = 95.572 (2)°	Lath, colourless
V = 1343.73 (11) Å3	0.40 × 0.20 × 0.02 mm
Z = 4

Bruker Nonius X8 APEXII CCD diffractometer	2367 independent reflections
Radiation source: fine-focus sealed tube	1868 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
ω and φ scans	θmax = 25.1°, θmin = 3.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −11→11
Tmin = 0.887, Tmax = 0.998	k = −9→9
15807 measured reflections	l = −21→20

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.080	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ2(Fo2) + (0.0341P)2 + 0.473P] where P = (Fo2 + 2Fc2)/3
2367 reflections	(Δ/σ)max < 0.001
204 parameters	Δρmax = 0.18 e Å−3
1 restraint	Δρmin = −0.17 e Å−3

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.

	x	y	z	Uiso*/Ueq
O1	0.25601 (10)	0.66416 (13)	0.32136 (5)	0.0262 (3)
O2	0.38752 (12)	0.75630 (15)	0.42277 (7)	0.0369 (3)
O3	0.62427 (10)	0.57401 (13)	0.46447 (5)	0.0245 (3)
O4	0.69302 (12)	0.76366 (15)	0.38150 (6)	0.0367 (3)
O5	0.07707 (13)	0.52229 (15)	0.41146 (6)	0.0373 (3)
H5	0.052 (3)	0.451 (3)	0.4443 (11)	0.082 (8)*
O6	0.00116 (13)	0.70903 (14)	0.49167 (6)	0.0351 (3)
C1	0.45005 (15)	0.49405 (19)	0.36384 (8)	0.0212 (3)
C2	0.40413 (16)	0.3714 (2)	0.31037 (8)	0.0249 (4)
H2A	0.3206	0.3914	0.2791	0.030*
C3	0.47842 (16)	0.2217 (2)	0.30243 (9)	0.0281 (4)
H3A	0.4461	0.1398	0.2656	0.034*
C4	0.59942 (17)	0.1906 (2)	0.34767 (9)	0.0296 (4)
H4A	0.6494	0.0863	0.3426	0.036*
C5	0.64823 (16)	0.3111 (2)	0.40048 (8)	0.0263 (4)
H5A	0.7320	0.2903	0.4314	0.032*
C6	0.57436 (15)	0.46175 (19)	0.40792 (8)	0.0213 (3)
C7	0.36674 (15)	0.6510 (2)	0.37434 (8)	0.0232 (4)
C8	0.67024 (15)	0.7322 (2)	0.44426 (9)	0.0266 (4)
C9	0.68674 (17)	0.8504 (2)	0.50933 (9)	0.0331 (4)
H9A	0.7316	0.9574	0.4953	0.050*
H9B	0.7447	0.7949	0.5501	0.050*
H9C	0.5948	0.8768	0.5254	0.050*
C10	0.17065 (15)	0.8088 (2)	0.32687 (8)	0.0236 (4)
C11	0.18395 (16)	0.9407 (2)	0.27723 (9)	0.0283 (4)
H11A	0.2497	0.9319	0.2415	0.034*
C12	0.10136 (16)	1.0862 (2)	0.27940 (9)	0.0305 (4)
H12A	0.1091	1.1765	0.2445	0.037*
C13	0.00762 (16)	1.1002 (2)	0.33224 (9)	0.0303 (4)
H13A	−0.0480	1.2009	0.3343	0.036*
C14	−0.00502 (16)	0.9675 (2)	0.38195 (9)	0.0273 (4)
H14A	−0.0691	0.9784	0.4185	0.033*
C15	0.07431 (15)	0.81807 (19)	0.37966 (8)	0.0234 (3)
C16	0.04899 (16)	0.6788 (2)	0.43270 (9)	0.0258 (4)

	U11	U22	U33	U12	U13	U23
O1	0.0273 (6)	0.0265 (6)	0.0240 (6)	0.0042 (5)	−0.0015 (5)	−0.0055 (5)
O2	0.0365 (7)	0.0319 (7)	0.0394 (7)	0.0092 (5)	−0.0106 (5)	−0.0158 (6)
O3	0.0298 (6)	0.0216 (6)	0.0218 (5)	−0.0006 (5)	0.0007 (4)	−0.0024 (5)
O4	0.0456 (7)	0.0353 (7)	0.0296 (7)	−0.0121 (6)	0.0064 (5)	0.0006 (5)
O5	0.0572 (8)	0.0227 (7)	0.0343 (7)	0.0042 (6)	0.0154 (6)	0.0015 (5)
O6	0.0490 (7)	0.0281 (7)	0.0299 (6)	0.0074 (5)	0.0123 (5)	0.0022 (5)
C1	0.0256 (8)	0.0192 (8)	0.0196 (8)	−0.0030 (6)	0.0066 (6)	0.0000 (6)
C2	0.0259 (8)	0.0258 (9)	0.0235 (8)	−0.0048 (7)	0.0047 (6)	−0.0016 (7)
C3	0.0339 (9)	0.0233 (9)	0.0284 (9)	−0.0048 (7)	0.0097 (7)	−0.0078 (7)
C4	0.0372 (9)	0.0212 (9)	0.0322 (9)	0.0034 (7)	0.0125 (8)	−0.0008 (7)
C5	0.0297 (8)	0.0254 (9)	0.0246 (8)	0.0025 (7)	0.0056 (7)	0.0011 (7)
C6	0.0269 (8)	0.0203 (8)	0.0175 (8)	−0.0032 (6)	0.0062 (6)	−0.0006 (6)
C7	0.0230 (8)	0.0235 (8)	0.0233 (8)	−0.0025 (6)	0.0025 (7)	−0.0007 (7)
C8	0.0227 (8)	0.0262 (9)	0.0303 (9)	−0.0005 (7)	0.0004 (7)	−0.0002 (7)
C9	0.0333 (9)	0.0316 (10)	0.0341 (9)	−0.0021 (7)	0.0019 (7)	−0.0074 (8)
C10	0.0221 (7)	0.0239 (9)	0.0235 (8)	0.0008 (6)	−0.0042 (6)	−0.0055 (7)
C11	0.0274 (8)	0.0316 (10)	0.0253 (8)	−0.0048 (7)	−0.0001 (7)	−0.0007 (7)
C12	0.0326 (9)	0.0275 (9)	0.0299 (9)	−0.0044 (7)	−0.0052 (7)	0.0059 (7)
C13	0.0288 (9)	0.0249 (9)	0.0356 (10)	0.0045 (7)	−0.0044 (7)	0.0019 (8)
C14	0.0232 (8)	0.0287 (9)	0.0293 (8)	0.0022 (7)	−0.0003 (7)	−0.0015 (7)
C15	0.0231 (8)	0.0234 (8)	0.0228 (8)	−0.0009 (6)	−0.0032 (6)	−0.0024 (7)
C16	0.0250 (8)	0.0248 (9)	0.0271 (9)	0.0035 (7)	−0.0002 (7)	−0.0026 (7)

O1—C7	1.3662 (18)	C5—C6	1.381 (2)
O1—C10	1.3998 (18)	C5—H5A	0.950
O2—C7	1.1995 (18)	C8—C9	1.488 (2)
O3—C8	1.3659 (19)	C9—H9A	0.980
O3—C6	1.3923 (18)	C9—H9B	0.980
O4—C8	1.2013 (18)	C9—H9C	0.980
O5—C16	1.3090 (19)	C10—C11	1.375 (2)
O5—H5	0.86 (1)	C10—C15	1.396 (2)
O6—C16	1.2242 (18)	C11—C12	1.383 (2)
C1—C6	1.395 (2)	C11—H11A	0.950
C1—C2	1.397 (2)	C12—C13	1.381 (2)
C1—C7	1.480 (2)	C12—H12A	0.950
C2—C3	1.378 (2)	C13—C14	1.379 (2)
C2—H2A	0.950	C13—H13A	0.950
C3—C4	1.378 (2)	C14—C15	1.391 (2)
C3—H3A	0.950	C14—H14A	0.950
C4—C5	1.385 (2)	C15—C16	1.480 (2)
C4—H4A	0.950
C7—O1—C10	115.71 (11)	C8—C9—H9A	109.5
C8—O3—C6	117.58 (11)	C8—C9—H9B	109.5
C16—O5—H5	108.2 (16)	H9A—C9—H9B	109.5
C6—C1—C2	117.99 (14)	C8—C9—H9C	109.5
C6—C1—C7	121.35 (13)	H9A—C9—H9C	109.5
C2—C1—C7	120.63 (14)	H9B—C9—H9C	109.5
C3—C2—C1	120.84 (15)	C11—C10—C15	121.20 (14)
C3—C2—H2A	119.6	C11—C10—O1	117.20 (13)
C1—C2—H2A	119.6	C15—C10—O1	121.59 (14)
C2—C3—C4	120.23 (15)	C10—C11—C12	119.87 (14)
C2—C3—H3A	119.9	C10—C11—H11A	120.1
C4—C3—H3A	119.9	C12—C11—H11A	120.1
C3—C4—C5	120.08 (14)	C13—C12—C11	120.00 (15)
C3—C4—H4A	120.0	C13—C12—H12A	120.0
C5—C4—H4A	120.0	C11—C12—H12A	120.0
C6—C5—C4	119.63 (15)	C14—C13—C12	119.82 (15)
C6—C5—H5A	120.2	C14—C13—H13A	120.1
C4—C5—H5A	120.2	C12—C13—H13A	120.1
C5—C6—O3	117.13 (13)	C13—C14—C15	121.24 (14)
C5—C6—C1	121.20 (14)	C13—C14—H14A	119.4
O3—C6—C1	121.54 (13)	C15—C14—H14A	119.4
O2—C7—O1	121.63 (14)	C14—C15—C10	117.83 (14)
O2—C7—C1	126.80 (14)	C14—C15—C16	117.59 (13)
O1—C7—C1	111.55 (12)	C10—C15—C16	124.57 (14)
O4—C8—O3	121.91 (14)	O6—C16—O5	122.61 (14)
O4—C8—C9	127.32 (15)	O6—C16—C15	121.59 (14)
O3—C8—C9	110.77 (13)	O5—C16—C15	115.77 (13)
C6—C1—C2—C3	1.1 (2)	C6—O3—C8—O4	−14.2 (2)
C7—C1—C2—C3	−177.36 (13)	C6—O3—C8—C9	166.09 (12)
C1—C2—C3—C4	0.3 (2)	C7—O1—C10—C11	104.36 (15)
C2—C3—C4—C5	−1.2 (2)	C7—O1—C10—C15	−76.66 (17)
C3—C4—C5—C6	0.6 (2)	C15—C10—C11—C12	0.3 (2)
C4—C5—C6—O3	176.69 (13)	O1—C10—C11—C12	179.32 (13)
C4—C5—C6—C1	0.9 (2)	C10—C11—C12—C13	1.2 (2)
C8—O3—C6—C5	115.45 (14)	C11—C12—C13—C14	−1.1 (2)
C8—O3—C6—C1	−68.76 (17)	C12—C13—C14—C15	−0.6 (2)
C2—C1—C6—C5	−1.7 (2)	C13—C14—C15—C10	2.0 (2)
C7—C1—C6—C5	176.74 (13)	C13—C14—C15—C16	−177.04 (14)
C2—C1—C6—O3	−177.31 (12)	C11—C10—C15—C14	−1.9 (2)
C7—C1—C6—O3	1.1 (2)	O1—C10—C15—C14	179.14 (13)
C10—O1—C7—O2	0.9 (2)	C11—C10—C15—C16	177.09 (14)
C10—O1—C7—C1	179.84 (11)	O1—C10—C15—C16	−1.8 (2)
C6—C1—C7—O2	−6.4 (2)	C14—C15—C16—O6	−25.3 (2)
C2—C1—C7—O2	172.01 (15)	C10—C15—C16—O6	155.67 (15)
C6—C1—C7—O1	174.74 (12)	C14—C15—C16—O5	152.75 (14)
C2—C1—C7—O1	−6.87 (18)	C10—C15—C16—O5	−26.3 (2)

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)

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)

Symmetry code: (i) .