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Acta Crystallogr Sect E Struct Rep Online. 2009 May 1; 65(Pt 5): o1096.
Published online 2009 April 22. doi:  10.1107/S160053680901321X
PMCID: PMC2977774

4,4′-(Hexane-1,6-diyldi­oxy)dianiline

Abstract

The complete molecule of the title compound, C18H24N2O2, is generated by a crystallographic inversion centre. The torsion angles in the hexa­methyl­ene chain are consistent with an anti­periplanar conformation, whereas the conformation of the O—CH2—CH2—CH2 unit is gauche. The three-dimensional crystal packing is stabilized by N—H(...)O and N—H(...)N hydrogen bonding.

Related literature

For aromatic diamines as building blocks for the preparation of high-performance polymers, see: Mehdipour-Ataei (2005 [triangle]; Mehdipour-Ataei et al. (2007 [triangle]). For the use of flexible linkages, see: Shao et al. (2007 [triangle]); Yin et al. (1998 [triangle]).

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Object name is e-65-o1096-scheme1.jpg

Experimental

Crystal data

  • C18H24N2O2
  • M r = 300.39
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-65-o1096-efi1.jpg
  • a = 5.4777 (6) Å
  • b = 13.6049 (12) Å
  • c = 21.7278 (18) Å
  • V = 1619.2 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.08 mm−1
  • T = 173 K
  • 0.33 × 0.23 × 0.11 mm

Data collection

  • Stoe IPDS-II two-circle diffractometer
  • Absorption correction: none
  • 9301 measured reflections
  • 1854 independent reflections
  • 1403 reflections with I > 2σ(I)
  • R int = 0.056

Refinement

  • R[F 2 > 2σ(F 2)] = 0.039
  • wR(F 2) = 0.103
  • S = 1.02
  • 1854 reflections
  • 109 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.24 e Å−3
  • Δρmin = −0.18 e Å−3

Data collection: X-AREA (Stoe & Cie, 2001 [triangle]); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: PLATON (Spek, 2009 [triangle]) and XP (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXL97.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680901321X/tk2416sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680901321X/tk2416Isup2.hkl

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

Acknowledgments

The authors are grateful to the Department of Chemistry, Quaid-i-Azam University, Islamabad, Pakistan, and the Institute for Inorganic Chemistry, University of Frankfurt, Germany, for providing laboratory and analytical facilities.

supplementary crystallographic information

Comment

Aromatic diamines are valuable building blocks for the preparation of high-performance polymers including polyamides, polyimides and polyureas (Mehdipour-Ataei, 2005). Therefore, these can be used to produce desired alterations in the chemical nature of macromolecular chains (Mehdipour-Ataei et al., 2007). Much research in recent years has focused on the design and synthesis of novel diamines in order to obtain suitable polymers. One of the popular approaches to achieve this goal is the introduction of flexible linkages such as an ether moiety (Shao et al., 2007) and/or methylene spacers (Yin et al., 1998) in the core structure of the diamines. These linkages increase the degree of freedom by reducing the segmental rotational barrier and inhibit close chain packing. The title compound, (I), in which flexible methylene spacers are present between the aryl ether moieties, is an outcome of efforts to modify the aromatic diamine monomers by flexible linkages in order to improve the processability and performance of the resulting polymers.

Molecules of (I) (Fig. 1) are located about a crystallographic centre of inversion. All torsion angles in the hexamethylene chain indicate an antiperiplanar conformation whereas the conformation of the O—CH2—CH2—CH2 unit is gauche. The crystal packing (Table 1) is stabilized by N—H···O and N—H···N hydrogen bonds which lead to a three-dimensional network.

Experimental

The title compound (I) was synthesized in two steps. In the first step, bis(4-nitrophenoxy)hexane was prepared by Williamson's reaction. A three-neck round bottom flask equipped with Dean-Stark trap, thermometer, magnetic stirrer and nitrogen inlet was charged with a suspension of 1,6-hexane diol (2.25 g; 19.1 mmol) and anhydrous potassium carbonate (5.3 g; 38.2 mmol) in a mixture of N,N'-dimethyl formamide (DMF) (60 ml) and toluene (20 ml), and refluxed (at 403–408 K) for 2 h for azeotropic removal of water. After cooling to 343–343 K, 1-fluoro-4-nitro benzene (4.05 ml; 38.2 mmol) was added and the mixture was again refluxed for 6 h. Subsequently, some toluene was distilled off and the resulting mixture was poured into 500 ml of chilled water after cooling to room temperature. The crude product was filtered as yellow solid, washed thoroughly with water and recrystallized from ethanol to afford bis(4-nitrophenoxy)hexane. In the second step, a two-neck flask was charged with 1,6-bis(4-nitrophenoxy)hexane (2.5 g; 6.94 mmol), hydrazine monohydrate (10 ml), ethanol (80 ml) and 0.1 g of 5% palladium on carbon (Pd–C). The mixture was refluxed for 18 h and then filtered to remove the Pd–C. The filtrate was concentrated on rotary evaporator to remove the solvent and the resulting crude solid was recrystallized from ethanol to afford colourless crystals suitable for X-ray analysis, which were stored in air-tight glass bottles for further studies. Yield 72%; m.p. 414 K. Elemental analysis. Found C, 72.03, H, 7.90, N, 9.25. Calculated for C18H24N2O2: C, 71.97, H, 8.05, N, 9.33; IR (KBr pellet) in cm-1: 3395, 3311 (NH2), 1632 (N-H bending), 1385 (C-N stretching), 1233 (C-O-C), 2935 (C—H aliphatic), 3219 (C—H aromatic). 1H NMR (CDCl3) δ: 3.92 (s, 4H, NH2), 6.40 (d, 4H, J = 3.0 Hz), 6.70 (d, 4H, J = 2.9 Hz), 3.88 (t, 4H), 1.78 (m, 4H), 1.51 (m, 4H) p.p.m. 13C NMR (CDCl3) δ: 147.52 (2 C, C4), 139.83 (2 C, C1), 116.42 (4 C, C2,2'), 115.67 (4 C, C3,3'), 68.54 (2 C, C5), 29.38 (2 C, C6), 25.91 (2 C, C7) p.p.m.

Refinement

H atoms bonded to C were geometrically positioned and refined using a riding model with with C—H(aromatic) = 0.95Å and CH(methylene) = 0.99 Å, and with U(H) = 1.2 Ueq(C). The H atoms bonded to N were freely refined, see Table 1 for distances.

Figures

Fig. 1.
Perspective view of (I) showing the atom labelling scheme and displacement ellipsoids at the 50% probability level. H atoms are drawn as spheres of arbitrary radii. Unlabelled atoms are related by the symmetry operator 1 - x, -y, 1 - z.

Crystal data

C18H24N2O2F(000) = 648
Mr = 300.39Dx = 1.232 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 6791 reflections
a = 5.4777 (6) Åθ = 3.6–27.7°
b = 13.6049 (12) ŵ = 0.08 mm1
c = 21.7278 (18) ÅT = 173 K
V = 1619.2 (3) Å3Plate, colourless
Z = 40.33 × 0.23 × 0.11 mm

Data collection

Stoe IPDS-II two-circle diffractometer1403 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.056
graphiteθmax = 27.6°, θmin = 3.5°
ω scansh = −7→5
9301 measured reflectionsk = −17→17
1854 independent reflectionsl = −24→28

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.039H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.103w = 1/[σ2(Fo2) + (0.0626P)2] where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max = 0.001
1854 reflectionsΔρmax = 0.24 e Å3
109 parametersΔρmin = −0.18 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: 0.016 (2)

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.
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.

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

xyzUiso*/Ueq
N10.9705 (2)0.55262 (7)0.71082 (5)0.0289 (3)
H1A1.131 (3)0.5464 (11)0.7257 (7)0.045 (4)*
H1B0.956 (3)0.6080 (11)0.6885 (7)0.044 (4)*
O10.60683 (17)0.20721 (5)0.60327 (4)0.0303 (2)
C10.8839 (2)0.46681 (8)0.68123 (5)0.0235 (3)
C20.6800 (2)0.47129 (8)0.64298 (5)0.0258 (3)
H20.60600.53320.63510.031*
C30.5818 (2)0.38691 (8)0.61598 (5)0.0255 (3)
H30.44320.39170.58990.031*
C40.6879 (2)0.29578 (8)0.62748 (5)0.0237 (3)
C50.8897 (2)0.29005 (8)0.66663 (5)0.0262 (3)
H50.96040.22790.67550.031*
C60.9879 (2)0.37456 (8)0.69278 (5)0.0259 (3)
H61.12700.36970.71870.031*
C70.3984 (2)0.20972 (8)0.56312 (5)0.0269 (3)
H7A0.43630.24780.52550.032*
H7B0.25820.24100.58410.032*
C80.3376 (2)0.10382 (8)0.54656 (5)0.0267 (3)
H8A0.17700.10240.52570.032*
H8B0.32270.06520.58500.032*
C90.5262 (2)0.05471 (7)0.50505 (5)0.0248 (3)
H9A0.69000.06210.52370.030*
H9B0.52820.08850.46470.030*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
N10.0355 (7)0.0239 (5)0.0274 (5)−0.0043 (4)−0.0043 (5)−0.0005 (4)
O10.0369 (6)0.0204 (4)0.0336 (5)−0.0005 (3)−0.0102 (4)−0.0031 (3)
C10.0284 (6)0.0230 (5)0.0192 (5)−0.0030 (4)0.0032 (5)−0.0002 (4)
C20.0311 (7)0.0213 (5)0.0251 (6)0.0025 (5)−0.0006 (5)0.0002 (4)
C30.0271 (6)0.0256 (6)0.0238 (5)0.0003 (4)−0.0023 (5)0.0001 (4)
C40.0277 (7)0.0209 (5)0.0226 (5)−0.0018 (4)0.0012 (5)−0.0021 (4)
C50.0295 (7)0.0222 (5)0.0269 (6)0.0036 (4)0.0000 (5)0.0001 (4)
C60.0249 (6)0.0287 (6)0.0241 (5)0.0004 (5)−0.0025 (5)0.0000 (4)
C70.0283 (7)0.0248 (6)0.0275 (6)0.0012 (5)−0.0018 (5)−0.0031 (4)
C80.0277 (7)0.0253 (6)0.0271 (6)−0.0030 (4)0.0004 (5)−0.0025 (4)
C90.0259 (6)0.0234 (6)0.0250 (5)−0.0041 (4)−0.0005 (5)−0.0015 (4)

Geometric parameters (Å, °)

N1—C11.4147 (14)C5—C61.3908 (16)
N1—H1A0.939 (18)C5—H50.9500
N1—H1B0.899 (16)C6—H60.9500
O1—C41.3879 (13)C7—C81.5218 (15)
O1—C71.4372 (15)C7—H7A0.9900
C1—C21.3937 (17)C7—H7B0.9900
C1—C61.4011 (15)C8—C91.5258 (16)
C2—C31.3968 (15)C8—H8A0.9900
C2—H20.9500C8—H8B0.9900
C3—C41.3919 (16)C9—C9i1.532 (2)
C3—H30.9500C9—H9A0.9900
C4—C51.3966 (17)C9—H9B0.9900
C1—N1—H1A113.3 (10)C5—C6—H6119.7
C1—N1—H1B114.7 (10)C1—C6—H6119.7
H1A—N1—H1B110.0 (14)O1—C7—C8107.15 (9)
C4—O1—C7117.63 (8)O1—C7—H7A110.3
C2—C1—C6118.16 (10)C8—C7—H7A110.3
C2—C1—N1120.25 (10)O1—C7—H7B110.3
C6—C1—N1121.43 (11)C8—C7—H7B110.3
C1—C2—C3121.54 (10)H7A—C7—H7B108.5
C1—C2—H2119.2C7—C8—C9113.96 (10)
C3—C2—H2119.2C7—C8—H8A108.8
C4—C3—C2119.72 (11)C9—C8—H8A108.8
C4—C3—H3120.1C7—C8—H8B108.8
C2—C3—H3120.1C9—C8—H8B108.8
O1—C4—C3124.86 (11)H8A—C8—H8B107.7
O1—C4—C5115.83 (9)C8—C9—C9i112.53 (12)
C3—C4—C5119.31 (10)C8—C9—H9A109.1
C6—C5—C4120.58 (10)C9i—C9—H9A109.1
C6—C5—H5119.7C8—C9—H9B109.1
C4—C5—H5119.7C9i—C9—H9B109.1
C5—C6—C1120.67 (11)H9A—C9—H9B107.8
C6—C1—C2—C3−0.75 (17)C3—C4—C5—C6−1.58 (18)
N1—C1—C2—C3−176.24 (11)C4—C5—C6—C11.14 (18)
C1—C2—C3—C40.31 (18)C2—C1—C6—C50.03 (17)
C7—O1—C4—C30.28 (17)N1—C1—C6—C5175.46 (10)
C7—O1—C4—C5179.52 (10)C4—O1—C7—C8−176.37 (9)
C2—C3—C4—O1−179.93 (11)O1—C7—C8—C9−69.25 (12)
C2—C3—C4—C50.85 (17)C7—C8—C9—C9i173.85 (12)
O1—C4—C5—C6179.13 (10)

Symmetry codes: (i) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N1—H1A···N1ii0.939 (18)2.318 (18)3.2248 (11)162.1 (13)
N1—H1B···O1iii0.899 (16)2.318 (16)3.1724 (14)158.6 (13)

Symmetry codes: (ii) x+1/2, y, −z+3/2; (iii) −x+3/2, y+1/2, z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: TK2416).

References

  • Mehdipour-Ataei, S. (2005). Eur. Polym. J.41, 65–71.
  • Mehdipour-Ataei, S., Tadjarodi, A. & Babanzadeh, S. (2007). Eur. Polym. J.43, 498–506.
  • Shao, Y., Li, Y., Zhao, X., Ma, T., Gong, C. & Yang, F. (2007). Eur. Polym. J.43, 4389–4397.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]
  • Stoe & Cie (2001). X-AREA Stoe & Cie, Darmstadt, Germany.
  • Yin, J., Ye, Y. F. & Wang, Z. G. (1998). Eur. Polym. J.34, 1839–1843.

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