Crystal structure of 1,4-dieth­oxy-9,10-anthra­quinone

Chitoshi Kitamura; Sining Li; Munenori Takehara; Yoshinori Inoue; Katsuhiko Ono; Takeshi Kawase

doi:10.1107/S2056989015011901

. 2015 Jun 24;71(Pt 7):o504–o505. doi: 10.1107/S2056989015011901

Crystal structure of 1,4-diethoxy-9,10-anthraquinone

Chitoshi Kitamura ^a,^*, Sining Li ^a, Munenori Takehara ^a, Yoshinori Inoue ^a, Katsuhiko Ono ^b, Takeshi Kawase ^c

PMCID: PMC4518951 PMID: 26279933

Abstract

The asymmetric unit of the title compound, C₁₈H₁₆O₄, contains two crystallographically independent molecules. The anthraquinone ring systems are slightly bent with dihedral angles of 2.33 (8) and 13.31 (9)° between the two terminal benzene rings. In the crystal, the two independent molecules adopt slipped-parallel π-overlap with an average interplanar distance of 3.45 Å, forming a dimer; the centroid–centroid distances of the π–π interactions are 3.6659 (15)–3.8987 (15) Å. The molecules are also linked by C—H⋯O interactions, forming a tape structure along the a-axis direction. The crystal packing is characterized by a dimer-herringbone pattern.

Keywords: crystal structure; 9,10-anthraquinone; crystallographically independent molecules; π–π interactions; C—H⋯O interactions

Related literature

For synthesis of alkoxy-substituted 9,10-anthraquinones, see: Kitamura et al. (2004 ▸). For background information on substitution effects of alkoxy-substituted 9,10-anthraquinones, see; Ohta et al. (2012 ▸). For related structures of 1,4-dipropoxy-9,10-anthraquinone polymorphs, see: Kitamura et al. (2015 ▸). graphic file with name e-71-0o504-scheme1.jpg

Experimental

Crystal data

C₁₈H₁₆O₄
M _r = 296.31
Monoclinic,
a = 13.5514 (11) Å
b = 14.7204 (11) Å
c = 14.5905 (10) Å
β = 90.604 (3)°
V = 2910.4 (4) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 223 K
0.56 × 0.40 × 0.36 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
27699 measured reflections
6645 independent reflections
3129 reflections with I > 2σ(I)
R _int = 0.045

Refinement

R[F ² > 2σ(F ²)] = 0.076
wR(F ²) = 0.273
S = 0.93
6645 reflections
397 parameters
H-atom parameters constrained
Δρ_max = 0.27 e Å⁻³
Δρ_min = −0.48 e Å⁻³

Data collection: PROCESS-AUTO (Rigaku, 1998 ▸); cell refinement: PROCESS-AUTO; data reduction: PROCESS-AUTO; program(s) used to solve structure: SIR2004 (Burla et al., 2005 ▸); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015 ▸); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ▸) and Mercury (Macrae et al., 2008 ▸); software used to prepare material for publication: WinGX (Farrugia, 2012 ▸).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S2056989015011901/is5404sup1.cif

e-71-0o504-sup1.cif^{(37.8KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015011901/is5404Isup2.hkl

e-71-0o504-Isup2.hkl^{(364.1KB, hkl)}

Click here for additional data file.^{(5.8KB, cml)}

Supporting information file. DOI: 10.1107/S2056989015011901/is5404Isup3.cml

Click here for additional data file.^{(1.2MB, tif)}

. DOI: 10.1107/S2056989015011901/is5404fig1.tif

The asymmetric unit of the title compound, showing the atomic numbering and 40% probability displacement ellipsoids.

Click here for additional data file.^{(1.8MB, tif)}

a . DOI: 10.1107/S2056989015011901/is5404fig2.tif

A packing diagram of the title compound viewed down the a axis, showing a dimer-herringbone pattern. Hydrogen atoms are omitted for clarity.

Click here for additional data file.^{(1.9MB, tif)}

. DOI: 10.1107/S2056989015011901/is5404fig3.tif

A packing diagram of the title compound, showing C—H⋯O interactions (blue lines).

CCDC reference: 1008606

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

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
C8AH8AO3B	0.94	2.48	3.234(3)	137
C8BH8BO3A	0.94	2.55	3.304(4)	137
C11AH11AO4B ⁱ	0.94	2.60	3.325(3)	135
C11BH11BO4A ⁱⁱ	0.94	2.46	3.199(4)	135

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

This work was supported by a Grant-in-Aid for Scientific Research (C) (No. 15 K05482) from the JSPS.

supplementary crystallographic information

S1. Comment

9,10-Anthraquinone is an important framework as a dye. Various kinds of hydroxy-substituted anthraquinone dyes have been manufactured. However, there were little reports on alkoxy-substituted anthraquinone. In recent years, we presented the effects of the alkoxy substitution on the optical properties of 2,6-dialkoxy and 2,3,6,7-tetraalkoxy derivatives in solution as well as in the solid state (Ohta et al., 2012). Very recently, we have reported crystal structures of two polymorphs of 1,4-dipropoxy-9,10-anthraquinone, which contained red and yellow solids (Kitamura et al., 2015). The red crystal exhibited an anti-parallel arrangement along the stacking direction. On the other hand, the yellow crystal showed a slipped-parallel arrangement. To search the effect of alkyl chain length on molecular packing, we prepared the title compound, 1,4-diethoxy-9,10-anthraquinone, (I). In this paper, we present the crystal structure of (I).

The molecular structure of (I) is shown in Fig. 1. Two crystallographically independent molecules were found in the asymmetric unit, although the two molecules had almost the same molecular structure. There was a difference in planarity between the two molecules. Thus, the anthraquinone framework was slightly bent at the central quinone ring. For example, the dihedral angle between the two terminal benzene rings in the anthraquinone was 2.33 (8)° for one molecule and 13.31 (9)° for the other. The packing structure displays a dimer-herringbone pattern (Fig. 2), which is completely different from those of 1,4-dipropoxy-9,10-anthraquinone polymorphs (Kitamura et al., 2015). In the dimer part, the two molecules adopt slipped-parallel π-stack with an average interplanar distance of 3.45 Å, which would result in a yellow color in the solid state. The crystal structure is also stabilized by C—H···O interactions along the lateral direction of molecules (Fig. 3).

S2. Experimental

The title compound was prepared according to our previously reported method (Kitamura et al., 2004). A mixture of 1,4-hydrooxy-9,10-anthraquinone (2.20 g, 9.16 mmol), K₂CO₃ (2.51 g, 18.1 mmol), ethyl p-toluenesulfonate (5.02 g, 25.1 mmol) in o-dichlorobenzene (15 ml) was heated at reflux for 3 h under N₂ gas. After cooling to room temperature, water (65 ml) was added to the reaction mixture. Then, the resulting solid was filtered off and washed with hexane to give the title compound (2.37 g, 87% yield) as a yellow solid. Single crystals suitable for X-ray analysis were obtained by slow evaporation from a CH₂Cl₂ solution (m.p. 172–175 °C). Elemental analysis for C₁₈H₁₆O₄: C 72.96, H 5.44. Found: C 72.75, H 5.51. TOF-MS(EI): m/z Calcd C₁₈H₁₆O₄: 296.1049. Found: 296.1074.