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Acta Crystallogr Sect E Struct Rep Online. 2010 January 1; 66(Pt 1): o130.
Published online 2009 December 12. doi:  10.1107/S1600536809052295
PMCID: PMC2980160

2,3-Bis(4-ethoxy­phen­yl)quinoxaline

Abstract

The title compound, C24H22N2O2, was prepared by condensation of 1,2-bis­(4-ethoxy­phen­yl)ethane-1,2-dione and 1,2-diamino­benzene. The asymmetric unit contains one half-mol­ecule, close to a twofold axis. The plane of the quinoxaline ring is twisted with respect to the planes of the two ethoxy­phenyl ring systems, exhibiting dihedral angles of 39.95 (9)°. The crystal packing is dominated by weak C—H(...)π inter­actions. No classical hydrogen bonds or stacking inter­actions are observed.

Related literature

For applications of quinoxaline derivatives, see: Seitz et al. (2002 [triangle]); He et al. (2003 [triangle]); Dailey et al. (2001 [triangle]). For the syntheses of quinoxaline derivatives, see: Bhosale et al. (2005 [triangle]); More et al. (2006 [triangle]); Raw et al. (2003 [triangle]). For the synthesis of the title compound, see: Heravi et al. (2006 [triangle]).

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Object name is e-66-0o130-scheme1.jpg

Experimental

Crystal data

  • C24H22N2O2
  • M r = 370.44
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-0o130-efi2.jpg
  • a = 19.4837 (18) Å
  • b = 11.2682 (11) Å
  • c = 9.2629 (9) Å
  • β = 100.196 (1)°
  • V = 2001.5 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.08 mm−1
  • T = 293 K
  • 0.37 × 0.27 × 0.24 mm

Data collection

  • Bruker SMART CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.972, T max = 0.981
  • 6487 measured reflections
  • 1743 independent reflections
  • 1560 reflections with I > 2σ(I)
  • R int = 0.028

Refinement

  • R[F 2 > 2σ(F 2)] = 0.035
  • wR(F 2) = 0.092
  • S = 1.03
  • 1743 reflections
  • 128 parameters
  • H-atom parameters constrained
  • Δρmax = 0.17 e Å−3
  • Δρmin = −0.12 e Å−3

Data collection: SMART (Bruker, 2004 [triangle]); cell refinement: SAINT (Bruker, 2004 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXL97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 (Farrugia, 1997 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809052295/bh2259sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809052295/bh2259Isup2.hkl

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

Acknowledgments

The authors thank the National Natural Science Foundation of China (grant No. 20376071).

supplementary crystallographic information

Comment

Quinoxaline derivatives are an important class of benzoheterocycles. They have found applications as anticancer, antiviral, and antibacterial agents (Seitz et al., 2002; He et al., 2003), and dyes (Dailey et al., 2001). In recent years, many synthesis of quinoxaline derivatives have been reported (Raw et al., 2003; Bhosale et al., 2005; More et al., 2006). The title compound is one of such quinoxaline derivatives. We have synthesized the title compound and report now its crystal structure.

The molecular structure of title compound is as shown in Fig. 1. The molecule lies on a twofold axis. The quinoxaline ring and two ethoxyphenyl rings are independent and planar. The quinoxaline ring is twisted with respect to the ethoxyphenyl ring with a dihedral angle of 39.95 (9)°. Packing is dominated by rather weak C—H···π interactions (Table 1). In contrast, no significant hydrogen bonds or stacking interactions are observed in the crystal structure.

Experimental

The title compound was prepared according to the procedure reported by Heravi et al. (2006). A mixture of 1,2-bis(4-ethoxyphenyl)ethane-1,2-dione (1 mmol), 1,2-diaminobenzene (1 mmol), and ammonium fluoride (10% mol) in CH3OH (5 ml) was stirred at room temperature. The progress of the reaction was monitored by TLC. After completion, CH2Cl2 was added to the reaction mixture. The product dissolves in CH2Cl2 and the catalyst separated easily from the mixture by filtration. Solvents evaporation afforded the crude product. The solid was recrystallized from ethanol. Single crystals suitable for X-ray data collection were obtained by recrystallization from a dichloromethane-methanol mixture.

Refinement

All H atoms were located geometrically and treated as riding, with C—H distances in the range 0.93–0.97 Å and Uiso(H)=1.2Ueq(parent atom) or Uiso(H)=1.5Ueq(parent atom) in the case of the methyl group.

Figures

Fig. 1.
The molecular structure of the title molecule, with 40% probability displacement ellipsoids. Atoms labeled with _2 are generated by symmetry 1 - x, y, 1/2 - z.

Crystal data

C24H22N2O2F(000) = 784
Mr = 370.44Dx = 1.229 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 3608 reflections
a = 19.4837 (18) Åθ = 5.6–52.7°
b = 11.2682 (11) ŵ = 0.08 mm1
c = 9.2629 (9) ÅT = 293 K
β = 100.196 (1)°Prism, yellow
V = 2001.5 (3) Å30.37 × 0.27 × 0.24 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer1743 independent reflections
Radiation source: fine-focus sealed tube1560 reflections with I > 2σ(I)
graphiteRint = 0.028
[var phi] and ω scansθmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)h = −23→22
Tmin = 0.972, Tmax = 0.981k = −12→13
6487 measured reflectionsl = −10→10

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.035H-atom parameters constrained
wR(F2) = 0.092w = 1/[σ2(Fo2) + (0.0422P)2 + 0.9006P] where P = (Fo2 + 2Fc2)/3
S = 1.03(Δ/σ)max < 0.001
1743 reflectionsΔρmax = 0.17 e Å3
128 parametersΔρmin = −0.12 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0289 (19)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
C10.46773 (6)−0.00154 (10)0.19704 (12)0.0281 (3)
N10.43983 (5)−0.10164 (8)0.14060 (11)0.0321 (3)
C20.47078 (6)−0.20565 (10)0.19257 (13)0.0333 (3)
C30.44262 (8)−0.31482 (11)0.13548 (16)0.0459 (4)
H30.4044−0.31570.05940.055*
C40.47143 (9)−0.41910 (12)0.19182 (17)0.0580 (4)
H40.4531−0.49080.15290.070*
O10.31520 (5)0.41927 (8)0.03771 (11)0.0503 (3)
C80.35080 (6)0.31489 (10)0.06662 (14)0.0369 (3)
C60.41928 (6)0.19601 (11)0.25439 (13)0.0365 (3)
H60.43950.18560.35230.044*
C100.39626 (6)0.12701 (10)0.00690 (13)0.0334 (3)
H100.40030.0690−0.06250.040*
C50.42812 (6)0.10907 (10)0.15155 (12)0.0294 (3)
C70.38108 (7)0.29661 (11)0.21256 (14)0.0402 (3)
H70.37540.35320.28260.048*
C90.35851 (6)0.22927 (11)−0.03675 (14)0.0368 (3)
H90.33850.2403−0.13470.044*
C110.28097 (7)0.44243 (12)−0.10928 (17)0.0514 (4)
H11A0.24760.3801−0.14280.062*
H11B0.31480.4455−0.17450.062*
C120.24435 (8)0.55950 (14)−0.1089 (2)0.0689 (5)
H12A0.22090.5777−0.20650.103*
H12B0.27780.6204−0.07550.103*
H12C0.21090.5552−0.04450.103*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0309 (6)0.0289 (6)0.0251 (6)−0.0019 (5)0.0067 (5)0.0001 (4)
N10.0342 (5)0.0298 (6)0.0320 (6)−0.0025 (4)0.0051 (4)−0.0004 (4)
C20.0394 (6)0.0289 (6)0.0328 (7)−0.0020 (5)0.0096 (5)−0.0004 (5)
C30.0582 (8)0.0346 (7)0.0437 (8)−0.0107 (6)0.0053 (6)−0.0041 (6)
C40.0851 (12)0.0279 (7)0.0607 (10)−0.0092 (7)0.0119 (8)−0.0052 (6)
O10.0515 (6)0.0377 (5)0.0575 (6)0.0140 (4)−0.0017 (5)0.0093 (4)
C80.0338 (6)0.0303 (7)0.0451 (8)0.0029 (5)0.0032 (5)0.0078 (5)
C60.0426 (7)0.0371 (7)0.0286 (6)0.0073 (5)0.0030 (5)0.0014 (5)
C100.0343 (6)0.0331 (7)0.0320 (7)−0.0020 (5)0.0037 (5)−0.0010 (5)
C50.0285 (5)0.0290 (6)0.0307 (6)−0.0010 (5)0.0048 (4)0.0015 (5)
C70.0472 (7)0.0345 (7)0.0383 (7)0.0093 (6)0.0061 (6)−0.0027 (5)
C90.0365 (6)0.0385 (7)0.0327 (7)−0.0014 (5)−0.0015 (5)0.0065 (5)
C110.0398 (7)0.0482 (8)0.0622 (10)0.0006 (6)−0.0024 (6)0.0242 (7)
C120.0434 (8)0.0553 (10)0.1049 (14)0.0103 (7)0.0049 (8)0.0361 (9)

Geometric parameters (Å, °)

C1—N11.3193 (14)C6—C71.3737 (17)
C1—C1i1.452 (2)C6—C51.3981 (16)
C1—C51.4871 (15)C6—H60.9300
N1—C21.3660 (15)C10—C91.3881 (17)
C2—C31.4111 (17)C10—C51.3882 (16)
C2—C2i1.414 (2)C10—H100.9300
C3—C41.3655 (19)C7—H70.9300
C3—H30.9300C9—H90.9300
C4—C4i1.406 (3)C11—C121.500 (2)
C4—H40.9300C11—H11A0.9700
O1—C81.3676 (14)C11—H11B0.9700
O1—C111.4301 (17)C12—H12A0.9600
C8—C91.3860 (18)C12—H12B0.9600
C8—C71.3912 (18)C12—H12C0.9600
N1—C1—C1i120.98 (6)C5—C10—H10119.2
N1—C1—C5116.59 (10)C10—C5—C6117.88 (11)
C1i—C1—C5122.38 (6)C10—C5—C1121.10 (10)
C1—N1—C2117.95 (10)C6—C5—C1120.97 (10)
N1—C2—C3119.85 (11)C6—C7—C8120.77 (11)
N1—C2—C2i120.77 (6)C6—C7—H7119.6
C3—C2—C2i119.33 (8)C8—C7—H7119.6
C4—C3—C2120.05 (13)C8—C9—C10119.56 (11)
C4—C3—H3120.0C8—C9—H9120.2
C2—C3—H3120.0C10—C9—H9120.2
C3—C4—C4i120.61 (8)O1—C11—C12107.47 (14)
C3—C4—H4119.7O1—C11—H11A110.2
C4i—C4—H4119.7C12—C11—H11A110.2
C8—O1—C11118.57 (11)O1—C11—H11B110.2
O1—C8—C9125.21 (11)C12—C11—H11B110.2
O1—C8—C7115.51 (11)H11A—C11—H11B108.5
C9—C8—C7119.28 (11)C11—C12—H12A109.5
C7—C6—C5120.80 (11)C11—C12—H12B109.5
C7—C6—H6119.6H12A—C12—H12B109.5
C5—C6—H6119.6C11—C12—H12C109.5
C9—C10—C5121.69 (11)H12A—C12—H12C109.5
C9—C10—H10119.2H12B—C12—H12C109.5

Symmetry codes: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the N1,C1,C1',N1',C2 ring and Cg2 is the centroid of the C5–C10 ring.
D—H···AD—HH···AD···AD—H···A
C10—H10···Cg1ii0.932.853.3936 (17)119
C11—H11A···Cg2iii0.962.933.743 (2)143

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BH2259).

References

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