1,4-Bis(4-amino­phen­oxy)butane

Mol­ecules of the title compound, C₁₆H₂₀N₂O₂, reside across crystallographic centres of inversion with one half-mol­ecule in the asymmetric unit. The bond lengths and angles are normal and the crystal packing is stabilized by N—H...N and N—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C)= 0.001 Å
• R factor = 0.036
• wR factor = 0.099
• Data-to-parameter ratio = 20.5

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S1. Comment

Aromatic polyamides are considered as one of the most important classes of polymers because they have excellent thermal, mechanical and electrical properties (Chol et al., 2001), as well as outstanding chemical resistance (Sroog, 1991). However, their applications are often limited due to poor solubility, partially due to strong interchain interactions (Butt et al., 2005). To overcome these limitations, many efforts have been made to improve the processability of the polyamides while maintaining their thermal and mechanical properties (Chol et al., 2001). For example, bulky lateral substituents (Yang et al., 2000), flexible alkyl side chains (Jung & Park, 1996), non-coplanar biphenyl groups, and flexible alkyl or aryl ether spacers (Liaw et al., 1998) have been used to enhance solubility and thus process ability. Incorporation of flexible segments such as –O–, –SO₂–, –CH₂– and –C(CF₃)₂–, and of bulky pendant groups such as tert-butyl and adamantyl, were found to be successful in altering crystallinity and intermolecular interactions to increase solubility (Eastmond et al., 1996). Bulky pendant groups increase the disorder in chains and hinder dense chain packing which enhance the solubility. Many efforts have been made in the design and synthesis of new diamines. The title compound (I) is the result of an attempt to prepare soluble and processable organic based aromatic polyamides and ferrocene containing polyamides.

Related literature

For related literature, see: Butt et al. (2005); Chol et al. (2001); Eastmond et al. (1996); Jung & Park (1996); Liaw et al. (1998); Yang et al. (2000).

For related literature, see: Im & Jung (2000); Lee & Jung (1998); Sroog (1991).

S2. Experimental

Synthesis of the organic diamine TN4 consists of two steps. Step-1: (N4) A mixture of 1.40 ml (0.015 mol) of 1,4-butanediol, 4.38 g (0.0318 moles) anhydrous K₂CO₃ and 5 g (0.0318 moles) p-nitrochlorobenzene in 80 ml of DMF was heated at 120°C for 24 h under a N₂ atmosphere. When the reaction was over the mixture was poured into 500 ml distilled water to form light yellow precipitat, which was collected by filtration and washed several times thoroughly with water. The crude product was recrystallized from ethanol. M.p. 132°C, Yield = 80%.

Step-2: A two neck flask was charged with (N4) 1 g, 10 mL of hydrazine monohydrate, 80 mL e thanol and 0.1 g of 5% palladium on carbon (Pd—C). The mixture was refluxed for 24 h and then filtered to remove the (Pd—C). The filtrate was concentrated on rotary evaporator to remove the solvent (ethanol). The white colored precipitates were then recrystallized from ethanol. m.p. = 134°C, yield 70%.

S3. Refinement

H atoms were found in a difference map, but those bonded to C were refined using a riding model with C—H = 0.95 Å and U_iso(H) = 1.2U_eq(C) [C—H = 0.99 Å for the methylene groups]. The H atoms bonded to N were freely refined.

Computing details

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 1991); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. Perspective view of the title compound (I) with the atom numbering; displacement ellipsoids are at the 50% probability level. Symmetry operator (A): -x + 1, -y + 2, -z.
	Fig. 2. Packing diagram of the title compound (I) with a view onto the bc plane. Hydrogen bonds are drawn as dashed lines.

1,4-Bis(4-aminophenoxy)butane

Crystal data

C16H20N2O2	Dx = 1.233 Mg m^−3
Mr = 272.34	Melting point: 407 K
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 18762 reflections
a = 5.2638 (4) Å	θ = 3.6–29.7°
b = 13.6385 (8) Å	µ = 0.08 mm^−1
c = 20.4415 (11) Å	T = 173 K
V = 1467.50 (16) Å^3	Block, colourless
Z = 4	0.42 × 0.39 × 0.27 mm
F(000) = 584

Data collection

Stoe IPDS II two-circle diffractometer	1847 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.043
Graphite monochromator	θmax = 29.6°, θmin = 3.6°
ω scans	h = −7→7
18475 measured reflections	k = −18→18
2051 independent reflections	l = −28→28

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.036	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.099	w = 1/[σ^2(Fo^2) + (0.0511P)^2 + 0.3016P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
2051 reflections	Δρmax = 0.27 e Å^−3
100 parameters	Δρmin = −0.18 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.024 (3)

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 (Ų)

	x	y	z	Uiso*/Ueq
N1	0.04075 (16)	0.52438 (6)	0.20593 (4)	0.03056 (18)
H1A	−0.118 (3)	0.5273 (9)	0.2238 (6)	0.041 (3)*
H1B	0.057 (3)	0.4711 (10)	0.1814 (7)	0.042 (3)*
O1	0.36952 (14)	0.87454 (5)	0.08907 (3)	0.03265 (18)
C1	0.11977 (16)	0.61127 (6)	0.17419 (4)	0.02505 (18)
C2	0.33000 (17)	0.61024 (6)	0.13248 (4)	0.02799 (19)
H2	0.4146	0.5500	0.1242	0.034*
C3	0.41864 (17)	0.69611 (6)	0.10265 (4)	0.02789 (19)
H3	0.5601	0.6937	0.0738	0.033*
C4	0.29826 (16)	0.78512 (6)	0.11548 (4)	0.02537 (18)
C5	0.09139 (17)	0.78744 (6)	0.15830 (4)	0.02801 (19)
H5	0.0111	0.8481	0.1679	0.034*
C6	0.00208 (16)	0.70152 (6)	0.18700 (4)	0.02793 (19)
H6	−0.1401	0.7040	0.2156	0.034*
C7	0.57284 (18)	0.87461 (6)	0.04201 (4)	0.0301 (2)
H7A	0.5284	0.8327	0.0042	0.036*
H7B	0.7305	0.8489	0.0621	0.036*
C8	0.61124 (16)	0.98013 (6)	0.01998 (4)	0.02869 (19)
H8A	0.7679	0.9841	−0.0067	0.034*
H8B	0.6355	1.0221	0.0590	0.034*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0364 (4)	0.0263 (4)	0.0290 (4)	−0.0052 (3)	0.0038 (3)	0.0005 (3)
O1	0.0411 (4)	0.0251 (3)	0.0318 (3)	−0.0013 (2)	0.0120 (3)	0.0033 (2)
C1	0.0284 (4)	0.0263 (4)	0.0205 (3)	−0.0045 (3)	−0.0032 (3)	0.0002 (3)
C2	0.0311 (4)	0.0252 (4)	0.0278 (4)	0.0007 (3)	0.0011 (3)	−0.0013 (3)
C3	0.0291 (4)	0.0278 (4)	0.0268 (4)	−0.0006 (3)	0.0043 (3)	−0.0006 (3)
C4	0.0292 (4)	0.0242 (4)	0.0227 (4)	−0.0025 (3)	−0.0006 (3)	0.0011 (3)
C5	0.0304 (4)	0.0270 (4)	0.0266 (4)	0.0028 (3)	0.0024 (3)	0.0009 (3)
C6	0.0269 (4)	0.0314 (4)	0.0254 (4)	−0.0006 (3)	0.0030 (3)	0.0015 (3)
C7	0.0312 (4)	0.0303 (4)	0.0288 (4)	−0.0011 (3)	0.0047 (3)	0.0033 (3)
C8	0.0282 (4)	0.0312 (4)	0.0266 (4)	−0.0064 (3)	0.0000 (3)	0.0032 (3)

Geometric parameters (Å, º)

N1—C1	1.4136 (11)	C4—C5	1.3975 (12)
N1—H1A	0.911 (14)	C5—C6	1.3923 (12)
N1—H1B	0.886 (14)	C5—H5	0.9500
O1—C4	1.3855 (10)	C6—H6	0.9500
O1—C7	1.4389 (10)	C7—C8	1.5214 (12)
C1—C2	1.3971 (12)	C7—H7A	0.9900
C1—C6	1.4026 (12)	C7—H7B	0.9900
C2—C3	1.4003 (12)	C8—C8^i	1.5273 (17)
C2—H2	0.9500	C8—H8A	0.9900
C3—C4	1.3942 (12)	C8—H8B	0.9900
C3—H3	0.9500
C1—N1—H1A	114.6 (8)	C6—C5—H5	119.7
C1—N1—H1B	113.5 (8)	C4—C5—H5	119.7
H1A—N1—H1B	110.7 (12)	C5—C6—C1	120.72 (8)
C4—O1—C7	117.55 (7)	C5—C6—H6	119.6
C2—C1—C6	118.20 (7)	C1—C6—H6	119.6
C2—C1—N1	120.32 (8)	O1—C7—C8	107.30 (7)
C6—C1—N1	121.33 (8)	O1—C7—H7A	110.3
C1—C2—C3	121.42 (8)	C8—C7—H7A	110.3
C1—C2—H2	119.3	O1—C7—H7B	110.3
C3—C2—H2	119.3	C8—C7—H7B	110.3
C4—C3—C2	119.66 (8)	H7A—C7—H7B	108.5
C4—C3—H3	120.2	C7—C8—C8^i	113.08 (9)
C2—C3—H3	120.2	C7—C8—H8A	109.0
O1—C4—C3	124.76 (8)	C8^i—C8—H8A	109.0
O1—C4—C5	115.79 (7)	C7—C8—H8B	109.0
C3—C4—C5	119.45 (7)	C8^i—C8—H8B	109.0
C6—C5—C4	120.52 (8)	H8A—C8—H8B	107.8
C6—C1—C2—C3	−1.61 (12)	O1—C4—C5—C6	179.24 (8)
N1—C1—C2—C3	−177.24 (8)	C3—C4—C5—C6	−1.34 (13)
C1—C2—C3—C4	1.11 (13)	C4—C5—C6—C1	0.83 (13)
C7—O1—C4—C3	3.89 (12)	C2—C1—C6—C5	0.64 (12)
C7—O1—C4—C5	−176.71 (7)	N1—C1—C6—C5	176.22 (8)
C2—C3—C4—O1	179.75 (8)	C4—O1—C7—C8	179.14 (7)
C2—C3—C4—C5	0.38 (13)	O1—C7—C8—C8^i	−68.00 (11)

Symmetry code: (i) −x+1, −y+2, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···N1^ii	0.911 (14)	2.302 (14)	3.1895 (9)	164.6 (11)
N1—H1B···O1^iii	0.886 (14)	2.334 (14)	3.1790 (11)	159.3 (11)

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