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Acta Cryst. (2008). E64, o2199    [ doi:10.1107/S1600536808034272 ]

(2E,6E)-2,6-Bis(4-ethoxybenzylidene)cyclohexanone

X. Shi, S. Li and Z. Liu

Abstract top

The title compound, C24H26O3, was prepared by the condensation reaction of 4-ethoxybenzaldehyde with cyclohexanone. The molecule has crystallographic mirror symmetry and exhibits a butterfly-shaped geometry, with a dihedral angle of 5.46 (1)° between the two benzene rings. Weak intermolecular C-H...[pi] interactions help stabilize the crystal structure.

Comment top

The development of highly efficient nonlinear optical crystals is extremely important for laser spectroscopy and laser processing. Bis(arylmethylidene) cycloalkanones are reported to exhibit promising nonlinear optical properties (Yu et al., 2000). In addiiton, these compounds are widely used as building blocks for the synthesis of biologically active heterocycles (Guilford et al., 1999) The title compound C24H26O3 (I) was prepared by the condensation reaction of 4-ethoxybenzaldehyde with cyclohexanone. The molecular structure of (I) is shown in Fig. 1. It has crystallographic mirror symmetry and exhibits a butterfly-shaped geometry. Similar structures have been observed in the related substituted cyclohexanone analogues reported by Ompraba et al. (2003) and Sun et al. (2007). A dihedral angle of 5.46 (1)° is found between the mean planes of the two benzene rings. Molecules are mainly connected by intermolecular weak C—H···π interactions (Table 1).

Related literature top

For related structures, see: Du et al. (2007); Liang et al. (2007); Sun et al. (2007); Zhou et al. (2007). For background information, see: Guilford et al. (1999); Ompraba et al. (2003); Yu et al. (2000). Cg1 is the centroid of atoms C6–C11.

Experimental top

The title compound was synthesized as previously described (Sun et al., 2007). 4-Ethoxybenzaldehyde (15.0 g, 0.1 mol) and cyclohexanone (4.9 g, 0.05 mol) were dissolved in 80 ml of ethanol. To this solution, a 10% NaOH aqueous solution (20 ml) was added dropwise with stirring at room temperature. The reaction mixture was stirred for a further 8 h and then poured into a mixture of 100 ml water and diluted hydrochloric acid. The precipitate was filtered and washed thoroughly with water and finally with ethanol. The product was dried at room temperature and crystallized from ethanol to give the title compound as pale yellow solid (12.7 g, yield 70%). Crystals of (I) suitable for X-ray data collection were obtained by slow evaporation of a CH2Cl2 and MeOH solution in a ratio of 3:2 at 293 K.

Refinement top

All H atoms were positioned geometrically (C—H = 0.93–0.97 Å) and refined using a riding model, with Uiso(H) = 1.2 Ueq(C) (1.5 Ueq(C) for methyl) of the parent atoms. In the absence of significant anomalous dispersion effects, Friedel pairs were averaged.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SMART (Bruker, 2001); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. View of the molecule of (I) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. Symmetry code "a" represents the operation 1-x, y, z
(2E,6E)-2,6-Bis(4-ethoxybenzylidene)cyclohexanone top
Crystal data top
C24H26O3F(000) = 776
Mr = 362.45Dx = 1.216 Mg m−3
Orthorhombic, Cmc21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C2c-2Cell parameters from 1880 reflections
a = 24.2516 (6) Åθ = 2.7–21.4°
b = 10.8459 (3) ŵ = 0.08 mm−1
c = 7.5270 (2) ÅT = 298 K
V = 1979.83 (9) Å3Block, colourless
Z = 40.20 × 0.10 × 0.10 mm
Data collection top
Bruker SMART 4K CCD area-detector
diffractometer		1026 independent reflections
Radiation source: fine-focus sealed tube879 reflections with I > 2σ(I)
graphiteRint = 0.121
φ and ω scansθmax = 25.5°, θmin = 1.7°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1997)		h = −24→29
Tmin = 0.974, Tmax = 0.992k = −12→13
6002 measured reflectionsl = −9→9
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.048Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.115H-atom parameters constrained
S = 1.05 w = 1/[σ2(Fo2) + (0.0642P)2]
where P = (Fo2 + 2Fc2)/3
1026 reflections(Δ/σ)max < 0.001
129 parametersΔρmax = 0.20 e Å−3
1 restraintΔρmin = −0.14 e Å−3
Crystal data top
C24H26O3V = 1979.83 (9) Å3
Mr = 362.45Z = 4
Orthorhombic, Cmc21Mo Kα radiation
a = 24.2516 (6) ŵ = 0.08 mm−1
b = 10.8459 (3) ÅT = 298 K
c = 7.5270 (2) Å0.20 × 0.10 × 0.10 mm
Data collection top
Bruker SMART 4K CCD area-detector
diffractometer		1026 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1997)		879 reflections with I > 2σ(I)
Tmin = 0.974, Tmax = 0.992Rint = 0.121
6002 measured reflectionsθmax = 25.5°
Refinement top
R[F2 > 2σ(F2)] = 0.048H-atom parameters constrained
wR(F2) = 0.115Δρmax = 0.20 e Å−3
S = 1.05Δρmin = −0.14 e Å−3
1026 reflectionsAbsolute structure: ?
129 parametersFlack parameter: ?
1 restraintRogers parameter: ?
Special details top

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. The authors have merged Friedel pairs before the final refinement. In the absence of anomalous scatterers, no attempt was made to establish the absolute configuration of the title compound.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.50000.2069 (4)0.1013 (7)0.0752 (13)
C20.44694 (11)0.1650 (2)0.1831 (4)0.0599 (7)
C30.44890 (11)0.0930 (3)0.3532 (4)0.0641 (8)
H3A0.44860.00560.32620.077*
H3B0.41630.11140.42310.077*
C40.50000.1232 (4)0.4615 (5)0.0713 (11)
H4A0.50000.21000.49260.086*
H4B0.50000.07550.57050.086*
C50.40084 (12)0.1962 (2)0.0943 (4)0.0604 (8)
H50.40670.2472−0.00330.072*
C60.34301 (12)0.1637 (2)0.1252 (3)0.0534 (7)
C70.32483 (12)0.0581 (2)0.2149 (4)0.0568 (8)
H70.35070.00590.26630.068*
C80.26987 (12)0.0298 (2)0.2288 (3)0.0561 (7)
H80.2590−0.04120.28850.067*
C90.23052 (12)0.1066 (2)0.1543 (4)0.0535 (7)
C100.24723 (12)0.2127 (2)0.0674 (4)0.0585 (7)
H100.22120.26580.01880.070*
C110.30222 (11)0.2389 (2)0.0536 (4)0.0572 (7)
H110.31280.3101−0.00620.069*
C120.13522 (12)0.1324 (3)0.0784 (6)0.0798 (10)
H12A0.14330.1310−0.04770.096*
H12B0.13310.21770.11680.096*
C130.08165 (14)0.0681 (4)0.1142 (7)0.1005 (14)
H13A0.0865−0.01930.10080.151*
H13B0.05430.09650.03160.151*
H13C0.06980.08580.23320.151*
O10.50000.2707 (5)−0.0304 (6)0.1303 (19)
O20.17725 (8)0.06933 (16)0.1745 (3)0.0673 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.074 (3)0.070 (2)0.082 (3)0.0000.0000.028 (2)
C20.0684 (18)0.0474 (13)0.0640 (18)0.0046 (12)0.0043 (15)0.0077 (13)
C30.0661 (18)0.0647 (19)0.0614 (17)0.0063 (13)0.0094 (15)0.0044 (15)
C40.085 (3)0.077 (3)0.052 (2)0.0000.0000.000 (2)
C50.073 (2)0.0483 (14)0.0598 (17)0.0014 (11)0.0048 (14)0.0111 (12)
C60.0702 (17)0.0420 (13)0.0481 (14)0.0040 (11)−0.0010 (13)0.0023 (11)
C70.071 (2)0.0422 (13)0.0567 (17)0.0091 (12)0.0011 (14)0.0086 (12)
C80.0723 (18)0.0427 (14)0.0532 (15)0.0006 (12)0.0008 (14)0.0082 (12)
C90.0663 (17)0.0460 (14)0.0482 (14)−0.0013 (11)0.0004 (13)−0.0063 (12)
C100.0701 (19)0.0449 (14)0.0605 (16)0.0083 (12)−0.0071 (14)0.0016 (13)
C110.0731 (17)0.0403 (14)0.0583 (15)−0.0021 (11)−0.0034 (15)0.0083 (11)
C120.072 (2)0.075 (2)0.092 (3)0.0082 (16)−0.008 (2)0.0095 (19)
C130.065 (2)0.099 (2)0.138 (4)0.0051 (17)−0.004 (2)0.008 (3)
O10.076 (2)0.170 (4)0.145 (4)0.0000.0000.110 (4)
O20.0661 (13)0.0624 (10)0.0733 (14)−0.0012 (9)−0.0051 (12)0.0077 (11)
Geometric parameters (Å, °) top
C1—O11.209 (6)C7—H70.9300
C1—C2i1.497 (4)C8—C91.385 (4)
C1—C21.497 (4)C8—H80.9300
C2—C51.346 (4)C9—O21.362 (3)
C2—C31.500 (4)C9—C101.384 (4)
C3—C41.519 (4)C10—C111.367 (4)
C3—H3A0.9700C10—H100.9300
C3—H3B0.9700C11—H110.9300
C4—C3i1.519 (4)C12—O21.425 (4)
C4—H4A0.9700C12—C131.499 (5)
C4—H4B0.9700C12—H12A0.9700
C5—C61.465 (4)C12—H12B0.9700
C5—H50.9300C13—H13A0.9600
C6—C111.391 (4)C13—H13B0.9600
C6—C71.400 (4)C13—H13C0.9600
C7—C81.372 (4)
O1—C1—C2i120.73 (18)C6—C7—H7119.1
O1—C1—C2120.73 (18)C7—C8—C9120.3 (2)
C2i—C1—C2118.5 (4)C7—C8—H8119.9
C5—C2—C1115.7 (3)C9—C8—H8119.9
C5—C2—C3125.5 (3)O2—C9—C10125.3 (2)
C1—C2—C3118.8 (3)O2—C9—C8115.4 (2)
C2—C3—C4111.8 (3)C10—C9—C8119.3 (3)
C2—C3—H3A109.3C11—C10—C9119.6 (3)
C4—C3—H3A109.3C11—C10—H10120.2
C2—C3—H3B109.3C9—C10—H10120.2
C4—C3—H3B109.3C10—C11—C6122.8 (3)
H3A—C3—H3B107.9C10—C11—H11118.6
C3i—C4—C3109.3 (3)C6—C11—H11118.6
C3i—C4—H4A109.8O2—C12—C13107.8 (3)
C3—C4—H4A109.8O2—C12—H12A110.2
C3i—C4—H4B109.8C13—C12—H12A110.2
C3—C4—H4B109.8O2—C12—H12B110.2
H4A—C4—H4B108.3C13—C12—H12B110.2
C2—C5—C6131.0 (3)H12A—C12—H12B108.5
C2—C5—H5114.5C12—C13—H13A109.5
C6—C5—H5114.5C12—C13—H13B109.5
C11—C6—C7116.3 (3)H13A—C13—H13B109.5
C11—C6—C5118.6 (2)C12—C13—H13C109.5
C7—C6—C5125.1 (3)H13A—C13—H13C109.5
C8—C7—C6121.7 (2)H13B—C13—H13C109.5
C8—C7—H7119.1C9—O2—C12118.6 (2)
O1—C1—C2—C54.1 (7)C5—C6—C7—C8−175.8 (3)
C2i—C1—C2—C5−174.1 (3)C6—C7—C8—C9−0.4 (4)
O1—C1—C2—C3−176.0 (5)C7—C8—C9—O2179.5 (3)
C2i—C1—C2—C35.7 (6)C7—C8—C9—C10−0.7 (4)
C5—C2—C3—C4−153.2 (3)O2—C9—C10—C11−179.0 (3)
C1—C2—C3—C427.0 (4)C8—C9—C10—C111.2 (4)
C2—C3—C4—C3i−59.6 (4)C9—C10—C11—C6−0.7 (5)
C1—C2—C5—C6174.4 (3)C7—C6—C11—C10−0.4 (4)
C3—C2—C5—C6−5.4 (5)C5—C6—C11—C10176.5 (3)
C2—C5—C6—C11158.6 (3)C10—C9—O2—C129.9 (4)
C2—C5—C6—C7−24.8 (5)C8—C9—O2—C12−170.3 (3)
C11—C6—C7—C81.0 (4)C13—C12—O2—C9176.1 (3)
Symmetry codes: (i) −x+1, y, z.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C8—H8···Cg1ii0.932.923.601 (2)132
Symmetry codes: (ii) x, −y, z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C8—H8···Cg1i0.932.923.601 (2)132
Symmetry codes: (i) x, −y, z+1/2.
Acknowledgements top

The authors are grateful to Xiangfan University for financial support.

references
References top

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