1,6-Bis(p-tol­yloxy)hexa­ne

Abstract

The title compound, C₂₀H₂₆O₂, crystallized with one half-mol­ecule in the asymmetric unit. The whole mol­ecule is generated by inversion symmetry, with the center of inversion being situated at the mid-point of the central –CH₂—CH₂- bond of the bridging hexane chain. In the crystal, mol­ecules stack in columns along the b axis. C—H⋯π inter­actions are present within the columns.

Related literature  

For the properties and synthesis of the title compound, see: Saito et al. (1988 ▶). For bond-length data, see: Allen et al. (1987 ▶).

Experimental  

Crystal data  

• C₂₀H₂₆O₂

• M _r = 298.41

• Monoclinic,

• a = 18.932 (12) Å

• b = 7.327 (4) Å

• c = 6.352 (4) Å

• β = 91.000 (13)°

• V = 881.0 (9) ų

• Z = 2

• Mo Kα radiation

• μ = 0.07 mm⁻¹

• T = 293 K

• 0.25 × 0.20 × 0.18 mm

Data collection  

• Enraf–Nonius CAD-4 diffractometer

• Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.983, T _max = 0.987

• 4572 measured reflections

• 1544 independent reflections

• 963 reflections with I > 2σ(I)

• R _int = 0.117

• 3 standard reflections every 200 reflections intensity decay: 1%

Refinement  

• R[F ² > 2σ(F ²)] = 0.077

• wR(F ²) = 0.316

• S = 1.10

• 1544 reflections

• 101 parameters

• H-atom parameters constrained

• Δρ_max = 0.36 e Å⁻³

• Δρ_min = −0.32 e Å⁻³

Data collection: CAD-4 Software (Enraf–Nonius, 1985 ▶); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms & Wocadlo,1995 ▶); 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.

Supplementary Material

CCDC reference: 999158

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

Table 1. Hydrogen-bond geometry (Å, °).

Cg is the centroid of the C2–C7 benzene ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4⋯Cg i	0.93	2.95	3.696 (4)	138
C7—H7⋯Cg ii	0.93	2.84	3.572 (4)	137

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

1. Comment

The title compound is used as a sensitizer for thermal recording materials, polyester-resin monomers and fire-resistant materials (Saito et al., 1988).

The molecular structure of the title compound is shown in Fig. 1. The bond lengths (Allen et al. (1987) and angles are within normal ranges. It crystallized with half a molecule in the asymmetric unit. The whole molecule is generated by inversion symmetry with the center of inversion being situated at the center of the C10—C10ⁱ bond of the bridging hexane chain [symmetry code: (i) -x, -y, -z + 2].

In the crystal, there are no intermolecular hydrogen bonds present (Fig. 2). The molecules stack in columns along the b axis and within the columns there are C—H···π interactions present (Table 1).

2. Experimental

The title compound was prepared by the reported procedure (Saito et al., 1988). Anhydrous potassium carbonate (6.2 g, 45 mmol) was added to a solution of 1,6-dibromohexane (2.5 g, 10.25 mmol) and 4-methoxyphenol (3.18 g, 25.6 mmol) in acetonitrile (100 ml). The mixture was stirred overnight at 338 K, and then filtered and the filtrate evaporated under reduced pressure. The residue was subjected to flash chromatography on silica gel, eluting with (10:1/petroleum ether:ethyl acetate) to give the title compound (Yield 2.13 g). Colourless block-like crystals of the title compound were obtained by slow evaporation of a solution in ethanol (20 ml), after ca. 7 days.

3. Refinement

All the H atoms were positioned geometrically and constrained to ride on their parent atoms: C—H = 0.93 - 0.97 Å with U_iso(H) = 1.5U_eq(C-methyl) and = 1.2U_eq(C) for other H atoms.

Figures

Fig. 1.

The molecular structure of the title molecule, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Fig. 2.

A view along the b axis of the crystal packing of the title compound.

Crystal data

C20H26O2	F(000) = 324
Mr = 298.41	Dx = 1.125 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1071 reflections
a = 18.932 (12) Å	θ = 2.2–23.2°
b = 7.327 (4) Å	µ = 0.07 mm−1
c = 6.352 (4) Å	T = 293 K
β = 91.000 (13)°	Block, colourless
V = 881.0 (9) Å3	0.25 × 0.20 × 0.18 mm
Z = 2

Data collection

Enraf–Nonius CAD-4 diffractometer	963 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.117
Graphite monochromator	θmax = 25.0°, θmin = 1.1°
ω/2θ scans	h = −22→21
Absorption correction: ψ scan (North et al., 1968)	k = −5→8
Tmin = 0.983, Tmax = 0.987	l = −7→7
4572 measured reflections	3 standard reflections every 200 reflections
1544 independent reflections	intensity decay: 1%

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.077	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.316	H-atom parameters constrained
S = 1.10	w = 1/[σ2(Fo2) + (0.2P)2] where P = (Fo2 + 2Fc2)/3
1544 reflections	(Δ/σ)max < 0.001
101 parameters	Δρmax = 0.36 e Å−3
0 restraints	Δρmin = −0.32 e Å−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
O1	0.15451 (11)	−0.0150 (4)	0.5211 (3)	0.0524 (8)
C1	0.4342 (2)	−0.0202 (7)	0.2221 (7)	0.0812 (15)
H1A	0.4508	−0.1439	0.2302	0.122*
H1B	0.4644	0.0567	0.3067	0.122*
H1C	0.4349	0.0203	0.0784	0.122*
C2	0.36013 (17)	−0.0103 (5)	0.3018 (6)	0.0535 (10)
C3	0.34523 (17)	0.0740 (5)	0.4910 (6)	0.0555 (10)
H3	0.3819	0.1277	0.5682	0.067*
C4	0.27798 (16)	0.0806 (5)	0.5681 (5)	0.0497 (10)
H4	0.2691	0.1409	0.6937	0.060*
C5	0.22302 (16)	−0.0041 (4)	0.4560 (5)	0.0400 (9)
C6	0.23675 (16)	−0.0871 (5)	0.2660 (4)	0.0439 (9)
H6	0.2002	−0.1416	0.1892	0.053*
C7	0.30380 (17)	−0.0892 (5)	0.1906 (5)	0.0502 (10)
H7	0.3121	−0.1448	0.0618	0.060*
C8	0.13751 (15)	0.0427 (5)	0.7259 (5)	0.0456 (9)
H8A	0.1378	0.1749	0.7336	0.055*
H8B	0.1719	−0.0042	0.8273	0.055*
C9	0.06519 (15)	−0.0294 (5)	0.7732 (4)	0.0449 (9)
H9A	0.0669	−0.1617	0.7745	0.054*
H9B	0.0327	0.0074	0.6612	0.054*
C10	0.03691 (14)	0.0366 (5)	0.9817 (4)	0.0403 (9)
H10A	0.0358	0.1690	0.9826	0.048*
H10B	0.0682	−0.0032	1.0951	0.048*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
O1	0.0479 (16)	0.0683 (18)	0.0413 (14)	−0.0032 (10)	0.0101 (10)	−0.0063 (11)
C1	0.064 (3)	0.093 (4)	0.088 (3)	0.002 (2)	0.034 (2)	−0.005 (3)
C2	0.053 (2)	0.043 (2)	0.065 (2)	0.0025 (15)	0.0202 (17)	0.0055 (17)
C3	0.051 (2)	0.051 (2)	0.065 (2)	−0.0086 (16)	0.0069 (16)	−0.0079 (18)
C4	0.055 (2)	0.049 (2)	0.0456 (18)	−0.0020 (15)	0.0089 (15)	−0.0109 (16)
C5	0.0429 (18)	0.0390 (19)	0.0385 (18)	0.0012 (13)	0.0136 (13)	0.0055 (13)
C6	0.0538 (19)	0.043 (2)	0.0346 (16)	−0.0022 (14)	0.0030 (13)	0.0022 (14)
C7	0.065 (2)	0.043 (2)	0.0433 (18)	0.0040 (16)	0.0137 (15)	−0.0009 (15)
C8	0.0469 (19)	0.049 (2)	0.0411 (18)	0.0042 (14)	0.0062 (14)	−0.0022 (14)
C9	0.0475 (19)	0.053 (2)	0.0341 (17)	−0.0005 (14)	0.0093 (13)	−0.0078 (14)
C10	0.0457 (19)	0.046 (2)	0.0297 (16)	0.0024 (13)	0.0059 (13)	−0.0025 (12)

Geometric parameters (Å, º)

O1—C5	1.371 (3)	C6—C7	1.365 (4)
O1—C8	1.410 (4)	C6—H6	0.9300
C1—C2	1.502 (4)	C7—H7	0.9300
C1—H1A	0.9600	C8—C9	1.503 (4)
C1—H1B	0.9600	C8—H8A	0.9700
C1—H1C	0.9600	C8—H8B	0.9700
C2—C3	1.385 (5)	C9—C10	1.516 (4)
C2—C7	1.394 (5)	C9—H9A	0.9700
C3—C4	1.373 (4)	C9—H9B	0.9700
C3—H3	0.9300	C10—C10i	1.519 (5)
C4—C5	1.396 (5)	C10—H10A	0.9700
C4—H4	0.9300	C10—H10B	0.9700
C5—C6	1.380 (4)
C5—O1—C8	119.6 (2)	C6—C7—C2	121.7 (3)
C2—C1—H1A	109.5	C6—C7—H7	119.2
C2—C1—H1B	109.5	C2—C7—H7	119.2
H1A—C1—H1B	109.5	O1—C8—C9	107.6 (3)
C2—C1—H1C	109.5	O1—C8—H8A	110.2
H1A—C1—H1C	109.5	C9—C8—H8A	110.2
H1B—C1—H1C	109.5	O1—C8—H8B	110.2
C3—C2—C7	117.3 (3)	C9—C8—H8B	110.2
C3—C2—C1	121.3 (4)	H8A—C8—H8B	108.5
C7—C2—C1	121.3 (3)	C8—C9—C10	113.5 (3)
C4—C3—C2	122.0 (3)	C8—C9—H9A	108.9
C4—C3—H3	119.0	C10—C9—H9A	108.9
C2—C3—H3	119.0	C8—C9—H9B	108.9
C3—C4—C5	119.3 (3)	C10—C9—H9B	108.9
C3—C4—H4	120.3	H9A—C9—H9B	107.7
C5—C4—H4	120.3	C9—C10—C10i	111.2 (3)
O1—C5—C6	115.6 (3)	C9—C10—H10A	109.4
O1—C5—C4	124.9 (3)	C10i—C10—H10A	109.4
C6—C5—C4	119.5 (3)	C9—C10—H10B	109.4
C7—C6—C5	120.2 (3)	C10i—C10—H10B	109.4
C7—C6—H6	119.9	H10A—C10—H10B	108.0
C5—C6—H6	119.9
C7—C2—C3—C4	0.0 (5)	C4—C5—C6—C7	1.3 (5)
C1—C2—C3—C4	−178.6 (4)	C5—C6—C7—C2	0.6 (5)
C2—C3—C4—C5	1.8 (5)	C3—C2—C7—C6	−1.2 (5)
C8—O1—C5—C6	171.1 (3)	C1—C2—C7—C6	177.4 (4)
C8—O1—C5—C4	−7.9 (5)	C5—O1—C8—C9	−165.3 (3)
C3—C4—C5—O1	176.6 (3)	O1—C8—C9—C10	−174.7 (3)
C3—C4—C5—C6	−2.4 (5)	C8—C9—C10—C10i	178.6 (3)
O1—C5—C6—C7	−177.8 (3)

Symmetry code: (i) −x, −y, −z+2.

Hydrogen-bond geometry (Å, º)

Cg is the centroid of the C2–C7 benzene ring.

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···Cgii	0.93	2.95	3.696 (4)	138
C7—H7···Cgiii	0.93	2.84	3.572 (4)	137

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