Crystal structure of 2-bromo-1,4-dihy­droxy-9,10-anthra­quinone

In an attempt to brominate 1,4-diprop­oxy-9,10-anthra­quinone, a mixture of products, including the title compound, C₁₄H₇BrO₄, was obtained. The mol­ecule is essentially planar (r.m.s. deviation = 0.029 Å) and two intra­molecular O—H...O hydrogen bonds occur. In the crystal, the mol­ecules are linked by weak C—H...O hydrogen bonds, Br...O contacts [3.240 (5) Å], and π–π stacking inter­actions [shortest centroid–centroid separation = 3.562 (4) Å], generating a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 200 K
• Mean [sigma](C-C) = 0.011 Å
• R factor = 0.057
• wR factor = 0.099
• Data-to-parameter ratio = 13.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT090_ALERT_3_C Poor Data / Parameter Ratio (Zmax > 18) ........       7.32 Note
PLAT341_ALERT_3_C Low Bond Precision on  C-C Bonds ...............     0.0113 Ang.
PLAT431_ALERT_2_C Short Inter HL..A  Contact Br1    ..  O3      ..       3.24 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H9     ..  O2      ..       2.69 Ang.
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......      3.776 Check
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          3 Report
PLAT975_ALERT_2_C Check Calcd Residual Density  0.79A From      O3       0.41 eA-3

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF     Please Do !
PLAT333_ALERT_2_G Check Large Av C6-Ring C-C Dist. C5     -C14           1.45 Ang.
PLAT850_ALERT_4_G Check Flack Parameter Exact Value 0.00 and su ..       0.01 Check
PLAT910_ALERT_3_G Missing # of FCF Reflections Below Th(Min) .....          3 Report
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600          3 Note

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   7 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   5 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Anthraquinone and its derivatives are important dyestuff molecules. In this work, we attempted to brominate 1,4-dipropoxy-9,10-anthraquinone (Kitamura et al., 2004) with elementary bromine in acetic acid to obtain 2-bromo-1,4-dipropoxy-9,10-anthraquinone. As a result, the reaction afforded a complex mixture of products containing 2-bromo-1,4-dihydroxy-9,10-anthraquinone, C₁₄H₇BrO₄ (I). Synthesis of the title compound, (I), was already reported by Peters & Tenny (1977) using a different method. However, the X-ray structure of (I) was not reported so far. We report here the crystal structure of the title compound, (I).

The title compound crystallizes in the orthorhombic space group Pca2₁ with a Flack parameter of 0.000 (11). The molecular structure of (I) is shown in Figure 1. The molecule is nearly planar with the maximum deviation of 0.053 (7) Å for O2. The bond length of C6—O3 and C13—O4 is 1.246 (9) Å and 1.238 (9) Å, respectively. The length of the single C—O bond of C1—O1 and C4—O2 is 1.340 (9) Å and 1.348 (10) Å, respectively. There are two intramolecular hydrogen bonds, O1—H1···O4 and O2—H2···O3. The distance of O1—O4 and O2—O3 is 2.536 (8) Å and 2.568 (9) Å, respectively. These values are in good agreement with those observed for 1,4-dihydroxy-9,10-anthraquinone (Nigam & Deppisch, 1980) and 2,3-dichloro-1,4-dihydroxy-9,10-anthraquinone (Hall et al., 1988).

As shown in Figure 2, in the crystal, molecules are linked by C—H···O hydrogen bonds (Table 1) and Br···O contacts [Br1···O3ⁱ = 3.240 (5) Å; symmetry code: (i) x - 1/2, -y + 1, z], whose value is shorter than the sum of van der Waals radii of bromine and oxygen atoms. The molecules are π-stacked along the a axis with an interplanar distance of 3.450 Å.

Related literature

For the original synthesis of the title compound, see: Peters & Tenny (1977). For related crystal structures of 1,4-dihydroxy-9,10-anthraquinone derivatives, see: Nigam & Deppisch (1980); Hall et al. (1988). For 1,4-dipropoxy-9,10-anthraquinone, see: Kitamura et al. (2004).

S2. Experimental

A mixture of 1,4-dipropoxy-9,10-anthraquinone (653 mg, 2.01 mmol), iron powder (50 mg, 0.89 mmol), bromine (0.40 g, 2.5 mmol) in acetic acid (20 ml) was stirred at 80 °C under air. The reaction was quenched with an aqueous solution of Na₂SO₃. Then the reaction products were precipitated. After filtration, the residue was subjected to column chromatography on silica gel using CH₂Cl₂-hexane as the eluent to afford the title compound (18 mg, 2.8% yield) as a red solid. Red platelets were obtained by slow evaporation of a CH₂Cl₂ solution.

S3. Refinement

All the aromatic H atoms were positioned geometrically and refined using a riding model with C—H = 0.95 Å and with U_iso(H) = 1.2U_eq(C). The H atoms of the OH groups were located in a difference Fourier map and freely refined [O1—H1 = 0.80 (9) Å and O2—H2 = 0.99 (10) Å].

Computing details

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: PROCESS-AUTO (Rigaku, 1998); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures

	Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids. The intramolecular hydrogen bonds are drawn by dashed lines.
	Fig. 2. The crystal packing of (I), showing short contacts of selected C–H···O and Br···O interactions by blue lines.

2-Bromo-1,4-dihydroxy-9,10-anthraquinone

Crystal data

C14H7BrO4	Dx = 1.905 Mg m^−3
Mr = 319.11	Melting point: 485 K
Orthorhombic, Pca21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2ac	Cell parameters from 12445 reflections
a = 18.977 (3) Å	θ = 3.4–27.5°
b = 3.7811 (4) Å	µ = 3.70 mm^−1
c = 15.5047 (18) Å	T = 200 K
V = 1112.5 (2) Å^3	Platelet, red
Z = 4	0.5 × 0.4 × 0.05 mm
F(000) = 632

Data collection

Rigaku R-AXIS RAPID diffractometer	2476 independent reflections
Radiation source: fine-focus sealed x-ray tube	2103 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.091
Detector resolution: 10 pixels mm^-1	θmax = 27.5°, θmin = 3.4°
ω scans	h = −24→24
Absorption correction: numerical (NUMABS; Higashi, 1999)	k = −4→4
Tmin = 0.322, Tmax = 0.912	l = −20→20
15045 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.057	w = 1/[σ^2(Fo^2) + (0.0171P)^2 + 1.2737P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.099	(Δ/σ)max = 0.001
S = 1.11	Δρmax = 0.85 e Å^−3
2476 reflections	Δρmin = −1.36 e Å^−3
179 parameters	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.017 (2)
0 constraints	Absolute structure: Flack x determined using 846 quotients [(I^+)-(I^-)]/[(I^+)+(I^-)] (Parsons & Flack, 2004)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.000 (11)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Br1	−0.12607 (3)	0.68820 (18)	0.29479 (9)	0.0301 (2)
O1	−0.0661 (3)	0.3974 (18)	0.4573 (4)	0.0354 (15)
O2	0.1215 (3)	0.3132 (19)	0.1883 (4)	0.0381 (15)
O3	0.2118 (2)	0.0436 (14)	0.2927 (4)	0.0350 (11)
O4	0.0247 (3)	0.1085 (17)	0.5543 (3)	0.0361 (15)
C1	−0.0179 (4)	0.373 (2)	0.3944 (5)	0.0242 (16)
C2	−0.0352 (4)	0.4934 (18)	0.3106 (5)	0.0258 (17)
C3	0.0105 (4)	0.476 (2)	0.2437 (5)	0.0259 (17)
H3	−0.0024	0.5634	0.1885	0.031*
C4	0.0786 (5)	0.325 (2)	0.2576 (5)	0.0262 (18)
C5	0.0979 (4)	0.209 (2)	0.3392 (5)	0.0222 (17)
C6	0.1685 (4)	0.061 (2)	0.3529 (5)	0.0271 (17)
C7	0.1876 (4)	−0.062 (2)	0.4400 (5)	0.0236 (15)
C8	0.2550 (4)	−0.196 (2)	0.4556 (5)	0.0280 (17)
H8	0.2885	−0.2062	0.4101	0.034*
C9	0.2731 (4)	−0.312 (2)	0.5369 (6)	0.0304 (18)
H9	0.319	−0.4027	0.5471	0.037*
C10	0.2248 (5)	−0.299 (2)	0.6038 (6)	0.0310 (19)
H10	0.2378	−0.3771	0.6598	0.037*
C11	0.1572 (4)	−0.171 (2)	0.5885 (5)	0.0282 (17)
H11	0.1239	−0.1641	0.6342	0.034*
C12	0.1385 (4)	−0.054 (2)	0.5078 (5)	0.0228 (16)
C13	0.0675 (4)	0.0989 (19)	0.4941 (5)	0.0234 (15)
C14	0.0487 (4)	0.2263 (19)	0.4077 (5)	0.0226 (15)
H1	−0.051 (5)	0.30 (2)	0.499 (6)	0.034*
H2	0.164 (5)	0.20 (2)	0.212 (6)	0.034*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0287 (4)	0.0284 (4)	0.0332 (4)	0.0024 (3)	−0.0052 (4)	0.0010 (8)
O1	0.030 (3)	0.052 (4)	0.024 (3)	0.008 (3)	0.002 (2)	0.003 (3)
O2	0.033 (3)	0.061 (4)	0.021 (3)	0.002 (3)	0.006 (2)	0.007 (3)
O3	0.031 (3)	0.048 (3)	0.025 (2)	0.003 (2)	0.006 (3)	0.000 (5)
O4	0.032 (4)	0.055 (5)	0.022 (3)	0.007 (3)	0.006 (2)	0.003 (3)
C1	0.025 (4)	0.026 (5)	0.021 (3)	−0.004 (3)	0.000 (3)	−0.003 (4)
C2	0.029 (4)	0.021 (4)	0.028 (5)	−0.002 (2)	−0.004 (3)	0.001 (4)
C3	0.038 (5)	0.017 (4)	0.023 (4)	−0.002 (3)	0.001 (3)	0.007 (3)
C4	0.027 (5)	0.028 (5)	0.023 (4)	−0.003 (3)	0.003 (3)	0.007 (4)
C5	0.025 (4)	0.018 (4)	0.023 (4)	−0.002 (3)	0.003 (3)	0.002 (4)
C6	0.030 (4)	0.025 (4)	0.026 (4)	−0.002 (3)	0.001 (3)	−0.003 (4)
C7	0.025 (4)	0.021 (4)	0.025 (4)	−0.003 (3)	0.002 (3)	−0.005 (3)
C8	0.025 (4)	0.028 (4)	0.031 (4)	0.000 (3)	0.003 (3)	0.004 (4)
C9	0.022 (4)	0.031 (4)	0.039 (5)	0.001 (3)	−0.003 (4)	0.002 (5)
C10	0.034 (5)	0.030 (5)	0.029 (4)	−0.001 (3)	−0.005 (4)	0.006 (5)
C11	0.029 (4)	0.031 (4)	0.024 (4)	0.000 (3)	0.000 (3)	−0.002 (4)
C12	0.030 (4)	0.017 (4)	0.022 (4)	−0.002 (3)	0.001 (3)	0.002 (3)
C13	0.030 (4)	0.022 (4)	0.019 (3)	−0.002 (3)	0.000 (3)	−0.001 (3)
C14	0.026 (4)	0.021 (4)	0.020 (3)	−0.001 (3)	0.001 (3)	−0.002 (3)

Geometric parameters (Å, º)

Br1—C2	1.890 (7)	C5—C6	1.467 (12)
O1—C1	1.340 (9)	C6—C7	1.474 (11)
O1—H1	0.80 (9)	C7—C8	1.396 (11)
O2—C4	1.348 (10)	C7—C12	1.405 (10)
O2—H2	0.99 (10)	C8—C9	1.379 (12)
O3—C6	1.246 (9)	C8—H8	0.95
O4—C13	1.238 (9)	C9—C10	1.384 (13)
C1—C14	1.397 (10)	C9—H9	0.95
C1—C2	1.414 (10)	C10—C11	1.391 (12)
C2—C3	1.354 (10)	C10—H10	0.95
C3—C4	1.431 (12)	C11—C12	1.375 (11)
C3—H3	0.95	C11—H11	0.95
C4—C5	1.387 (10)	C12—C13	1.481 (10)
C5—C14	1.416 (10)	C13—C14	1.467 (10)
C1—O1—H1	108 (7)	C12—C7—C6	120.9 (7)
C4—O2—H2	102 (5)	C9—C8—C7	120.0 (7)
O1—C1—C14	122.5 (7)	C9—C8—H8	120
O1—C1—C2	119.2 (7)	C7—C8—H8	120
C14—C1—C2	118.3 (7)	C8—C9—C10	120.6 (8)
C3—C2—C1	122.6 (7)	C8—C9—H9	119.7
C3—C2—Br1	120.2 (6)	C10—C9—H9	119.7
C1—C2—Br1	117.1 (5)	C9—C10—C11	119.7 (8)
C2—C3—C4	118.8 (7)	C9—C10—H10	120.2
C2—C3—H3	120.6	C11—C10—H10	120.2
C4—C3—H3	120.6	C12—C11—C10	120.4 (7)
O2—C4—C5	123.9 (8)	C12—C11—H11	119.8
O2—C4—C3	116.0 (7)	C10—C11—H11	119.8
C5—C4—C3	120.2 (7)	C11—C12—C7	120.1 (7)
C4—C5—C14	119.7 (7)	C11—C12—C13	119.4 (7)
C4—C5—C6	119.6 (7)	C7—C12—C13	120.4 (7)
C14—C5—C6	120.7 (7)	O4—C13—C14	121.3 (7)
O3—C6—C5	120.9 (8)	O4—C13—C12	120.0 (7)
O3—C6—C7	120.5 (7)	C14—C13—C12	118.6 (6)
C5—C6—C7	118.6 (7)	C1—C14—C5	120.3 (7)
C8—C7—C12	119.2 (7)	C1—C14—C13	119.1 (7)
C8—C7—C6	119.9 (7)	C5—C14—C13	120.6 (7)
O1—C1—C2—C3	−179.7 (7)	C9—C10—C11—C12	−0.7 (14)
C14—C1—C2—C3	−1.1 (11)	C10—C11—C12—C7	−0.1 (13)
O1—C1—C2—Br1	1.0 (9)	C10—C11—C12—C13	−176.8 (7)
C14—C1—C2—Br1	179.6 (5)	C8—C7—C12—C11	1.0 (12)
C1—C2—C3—C4	1.2 (12)	C6—C7—C12—C11	179.8 (8)
Br1—C2—C3—C4	−179.5 (6)	C8—C7—C12—C13	177.6 (7)
C2—C3—C4—O2	179.5 (7)	C6—C7—C12—C13	−3.6 (11)
C2—C3—C4—C5	−2.2 (13)	C11—C12—C13—O4	−2.7 (12)
O2—C4—C5—C14	−178.8 (7)	C7—C12—C13—O4	−179.3 (8)
C3—C4—C5—C14	3.0 (14)	C11—C12—C13—C14	179.3 (7)
O2—C4—C5—C6	−0.7 (15)	C7—C12—C13—C14	2.6 (11)
C3—C4—C5—C6	−178.8 (7)	O1—C1—C14—C5	−179.6 (7)
C4—C5—C6—O3	1.6 (13)	C2—C1—C14—C5	1.9 (11)
C14—C5—C6—O3	179.6 (7)	O1—C1—C14—C13	−1.2 (11)
C4—C5—C6—C7	−179.6 (8)	C2—C1—C14—C13	−179.8 (6)
C14—C5—C6—C7	−1.5 (11)	C4—C5—C14—C1	−2.9 (12)
O3—C6—C7—C8	0.7 (12)	C6—C5—C14—C1	179.0 (7)
C5—C6—C7—C8	−178.2 (8)	C4—C5—C14—C13	178.7 (8)
O3—C6—C7—C12	−178.2 (7)	C6—C5—C14—C13	0.7 (11)
C5—C6—C7—C12	3.0 (11)	O4—C13—C14—C1	2.5 (11)
C12—C7—C8—C9	−0.9 (13)	C12—C13—C14—C1	−179.5 (7)
C6—C7—C8—C9	−179.8 (8)	O4—C13—C14—C5	−179.2 (7)
C7—C8—C9—C10	0.1 (14)	C12—C13—C14—C5	−1.1 (11)
C8—C9—C10—C11	0.8 (14)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O4	0.80 (9)	1.82 (9)	2.536 (8)	148 (9)
O2—H2···O3	0.99 (10)	1.65 (10)	2.568 (9)	152 (8)
C3—H3···O4^i	0.95	2.46	3.396 (9)	169
C9—H9···O1^ii	0.95	2.59	3.308 (10)	133
C9—H9···O2^iii	0.95	2.69	3.394 (10)	132

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