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The skeleton of the title molecule, C18H38O2, is all-trans and the molecules aggregate to form a layer structure along the c axis as in a smectic C liquid crystal. The inclination angle of the long axis of the molecule to the layer plane is the same in each layer, but the direction of the long axis is opposite in alternate layers. These features are very similar to those of the homologues with an even number of C atoms, but different from those with an odd number.
Supporting information
CCDC reference: 159743
Key indicators
- Single-crystal X-ray study
- T = 298 K
- Mean (C-C) = 0.003 Å
- R factor = 0.045
- wR factor = 0.065
- Data-to-parameter ratio = 10.9
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
According to the conventional method, the title compound, (I), was synthesized
from commercially available octadecanedioic acid (Tokyo Kasei Kogyo Co. Ltd)
by esterification and reduction with LiAlH4. The single-crystal used for
analysis was grown by very slow evaporation from a solution in a mixed solvent
system comprising methanol, ethyl acetate and dimetylbenzene (1:1:3 ratio).
All H atoms, including hydroxyl H atoms, were fixed in idealized positions.
Data collection: MSC/AFC Diffractometer Control Software
(Molecular Structure Corporation, 1992); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN
(Molecular Structure Corporation, 1995); program(s) used to solve structure: SAPI91
(Fan, 1991); program(s) used to refine structure: TEXSAN; software used to prepare material for publication: TEXSAN.
Crystal data top
C18H38O2 | F(000) = 324 |
Mr = 286.50 | Dx = 1.047 Mg m−3 |
Monoclinic, P21/c | Cu Kα radiation, λ = 1.5418 Å |
a = 4.998 (2) Å | Cell parameters from 24 reflections |
b = 5.220 (2) Å | θ = 9.3–20.1° |
c = 34.853 (2) Å | µ = 0.50 mm−1 |
β = 92.04 (2)° | T = 298 K |
V = 908.8 (5) Å3 | Plate, colorless |
Z = 2 | 0.40 × 0.20 × 0.02 mm |
Data collection top
Rigaku AFC-5R diffractometer | 991 reflections with I > 2σ(I) |
Radiation source: Rigaku rotating anode | Rint = 0.025 |
Graphite monochromator | θmax = 70.5°, θmin = 2.5° |
ω–2θ scans | h = −2→6 |
Absorption correction: ψ scans (North et al., 1968) | k = 0→5 |
Tmin = 0.929, Tmax = 1 | l = −42→42 |
2843 measured reflections | 3 standard reflections every 150 reflections |
1802 independent reflections | intensity decay: 2.6% |
Refinement top
Refinement on F | 0 restraints |
Least-squares matrix: full | 0 constraints |
R[F2 > 2σ(F2)] = 0.045 | H-atom parameters not refined |
wR(F2) = 0.065 | w = 1/[σ2(Fo) + 0.00053|Fo|2] |
S = 1.67 | (Δ/σ)max < 0.001 |
991 reflections | Δρmax = 0.12 e Å−3 |
91 parameters | Δρmin = −0.11 e Å−3 |
Crystal data top
C18H38O2 | V = 908.8 (5) Å3 |
Mr = 286.50 | Z = 2 |
Monoclinic, P21/c | Cu Kα radiation |
a = 4.998 (2) Å | µ = 0.50 mm−1 |
b = 5.220 (2) Å | T = 298 K |
c = 34.853 (2) Å | 0.40 × 0.20 × 0.02 mm |
β = 92.04 (2)° | |
Data collection top
Rigaku AFC-5R diffractometer | 991 reflections with I > 2σ(I) |
Absorption correction: ψ scans (North et al., 1968) | Rint = 0.025 |
Tmin = 0.929, Tmax = 1 | 3 standard reflections every 150 reflections |
2843 measured reflections | intensity decay: 2.6% |
1802 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.065 | H-atom parameters not refined |
S = 1.67 | Δρmax = 0.12 e Å−3 |
991 reflections | Δρmin = −0.11 e Å−3 |
91 parameters | |
Special details top
Experimental. none |
Geometry. none |
Refinement. None |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 1.4119 (3) | −0.4953 (3) | 0.23943 (4) | 0.0802 (5) | |
C1 | 1.2271 (4) | −0.5358 (4) | 0.20834 (5) | 0.0599 (6) | |
C2 | 1.1288 (4) | −0.2830 (4) | 0.19336 (5) | 0.0540 (5) | |
C3 | 0.9330 (4) | −0.3089 (4) | 0.15912 (5) | 0.0517 (5) | |
C4 | 0.8304 (4) | −0.0540 (4) | 0.14358 (5) | 0.0514 (5) | |
C5 | 0.6396 (4) | −0.0809 (4) | 0.10891 (5) | 0.0513 (5) | |
C6 | 0.5365 (4) | 0.1724 (4) | 0.09318 (5) | 0.0500 (5) | |
C7 | 0.3465 (4) | 0.1468 (4) | 0.05827 (5) | 0.0500 (5) | |
C8 | 0.2426 (4) | 0.4007 (4) | 0.04263 (5) | 0.0501 (5) | |
C9 | 0.0519 (4) | 0.3726 (4) | 0.00781 (5) | 0.0496 (6) | |
H0 | 1.4782 | −0.6526 | 0.2493 | 0.0916* | |
H1a | 1.3082 | −0.6345 | 0.1882 | 0.0799* | |
H1b | 1.0770 | −0.6387 | 0.2167 | 0.0799* | |
H2a | 1.2796 | −0.1823 | 0.1854 | 0.0655* | |
H2b | 1.0437 | −0.1900 | 0.2132 | 0.0655* | |
H3a | 1.0188 | −0.3972 | 0.1390 | 0.0649* | |
H3b | 0.7832 | −0.4075 | 0.1667 | 0.0649* | |
H4a | 0.9802 | 0.0478 | 0.1364 | 0.0598* | |
H4b | 0.7398 | 0.0337 | 0.1633 | 0.0598* | |
H5a | 0.7313 | −0.1706 | 0.0889 | 0.0631* | |
H5b | 0.4911 | −0.1860 | 0.1158 | 0.0631* | |
H6a | 0.6855 | 0.2788 | 0.0862 | 0.0601* | |
H6b | 0.4449 | 0.2630 | 0.1130 | 0.0601* | |
H7a | 0.4376 | 0.0570 | 0.0384 | 0.0621* | |
H7b | 0.1970 | 0.0410 | 0.0652 | 0.0621* | |
H8a | 0.3905 | 0.5056 | 0.0355 | 0.0607* | |
H8b | 0.1502 | 0.4899 | 0.0624 | 0.0607* | |
H9a | 0.1427 | 0.2828 | −0.0120 | 0.0594* | |
H9b | −0.0979 | 0.2686 | 0.0149 | 0.0594* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.096 (1) | 0.0647 (10) | 0.0759 (9) | −0.0011 (8) | −0.0557 (8) | 0.0046 (8) |
C1 | 0.068 (1) | 0.056 (1) | 0.0534 (10) | −0.0013 (10) | −0.0282 (9) | 0.0024 (9) |
C2 | 0.059 (1) | 0.056 (1) | 0.0466 (9) | 0.0017 (9) | −0.0176 (8) | −0.0008 (8) |
C3 | 0.054 (1) | 0.052 (1) | 0.0479 (9) | −0.0045 (9) | −0.0158 (8) | 0.0034 (8) |
C4 | 0.0525 (10) | 0.051 (1) | 0.0490 (9) | −0.0041 (9) | −0.0152 (8) | 0.0031 (8) |
C5 | 0.054 (1) | 0.051 (1) | 0.0473 (9) | −0.0007 (9) | −0.0168 (8) | 0.0010 (8) |
C6 | 0.054 (1) | 0.048 (1) | 0.0471 (10) | −0.0008 (8) | −0.0163 (8) | 0.0002 (8) |
C7 | 0.054 (1) | 0.049 (1) | 0.0462 (9) | −0.0031 (9) | −0.0148 (8) | 0.0011 (8) |
C8 | 0.053 (1) | 0.049 (1) | 0.0475 (10) | −0.0032 (8) | −0.0155 (8) | 0.0020 (7) |
C9 | 0.055 (1) | 0.049 (1) | 0.0442 (10) | −0.0019 (8) | −0.0159 (8) | 0.0026 (7) |
Geometric parameters (Å, º) top
O1—C1 | 1.414 (2) | C5—C6 | 1.515 (2) |
C1—C2 | 1.496 (3) | C6—C7 | 1.523 (2) |
C2—C3 | 1.522 (2) | C7—C8 | 1.518 (3) |
C3—C4 | 1.519 (2) | C8—C9 | 1.523 (2) |
C4—C5 | 1.519 (2) | C9—C9i | 1.521 (4) |
| | | |
O1···O1ii | 2.843 (2) | O1···C1ii | 3.477 (2) |
O1···O1iii | 2.843 (2) | O1···C2iii | 3.554 (2) |
| | | |
O1—C1—C2 | 109.4 (1) | C5—C6—C7 | 114.0 (1) |
C1—C2—C3 | 112.9 (2) | C6—C7—C8 | 114.0 (2) |
C2—C3—C4 | 113.7 (2) | C7—C8—C9 | 113.5 (1) |
C3—C4—C5 | 113.4 (1) | C8—C9—C9i | 113.4 (2) |
C4—C5—C6 | 113.8 (2) | | |
Symmetry codes: (i) −x, −y+1, −z; (ii) −x+3, y+1/2, −z+1/2; (iii) −x+3, y−1/2, −z+1/2. |
Experimental details
Crystal data |
Chemical formula | C18H38O2 |
Mr | 286.50 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 298 |
a, b, c (Å) | 4.998 (2), 5.220 (2), 34.853 (2) |
β (°) | 92.04 (2) |
V (Å3) | 908.8 (5) |
Z | 2 |
Radiation type | Cu Kα |
µ (mm−1) | 0.50 |
Crystal size (mm) | 0.40 × 0.20 × 0.02 |
|
Data collection |
Diffractometer | Rigaku AFC-5R diffractometer |
Absorption correction | ψ scans (North et al., 1968) |
Tmin, Tmax | 0.929, 1 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2843, 1802, 991 |
Rint | 0.025 |
(sin θ/λ)max (Å−1) | 0.612 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.065, 1.67 |
No. of reflections | 991 |
No. of parameters | 91 |
H-atom treatment | H-atom parameters not refined |
Δρmax, Δρmin (e Å−3) | 0.12, −0.11 |
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Crystal structures of long-chain compounds such as n-alkanes (Müller, 1928) and n-higher primary alcohols (e.g. Watanabe, 1961; Seto, 1962), have been studied by many researchers from the viewpoint of basic polymer science. According to those results, the compounds have a simple straight hydrocarbon chain as a skeleton and the molecular shape can be regarded as a rod-like, which is one of the typical features of liquid crystal molecules. In addition, some long-chain compounds construct a layer structure in the crystal state, which is similar to that of a smectic phase of liquid crystals. Therefore, these compounds have been studied from a structural point of view as models for smectic liquid crystals.
We have already reported molecular and crystal structure of α,ω-alkanediols containing from 10 through 17 and 21 C atoms, these were investigated by Nakamura and co-workers: 1,10-decanediol (Nakamura & Sato, 1999a), 1,11-undecanediol (Nakamura et al., 1999), 1,12-dodecanediol (Nakamura & Setodoi, 1997), 1,13-tridecanediol (Nakamura et al., 1997), 1,14-tetradecanediol (Nakamura & Sato, 1999b), 1,15-pentadecanediol (Nakamura et al., 2000), 1,16-hexadecanediol (Nakamura & Yamamoto, 1994), 1,17-heptadecanediol (Nakamura et al., 2001) and 1,21-henicosanediol (Nakamura et al., 2000a). The results showed a clear distinction in the structures between the compounds with an even number of C atoms and those with an odd number of C atoms. In the α,ω-alkanediols with even number of C atoms, the hydroxyl groups located at both ends of a hydrocarbon skeleton showed an all-trans conformation with respect to the skeleton. These molecules were arranged making layers in a herring-bone fashion, just like the chiral smectic C liquid crystals. On the other hand, in the α,ω-alkanediols with an odd number of C atoms, one hydroxyl group had gauche conformation with respect to the hydrocarbon skeleton, whereas another hydroxyl group had trans conformation. In this case, molecules made a layer structure which was very similar to that of the smectic A liquid crystals. In addition, phase transition of α,ω-alkanediols from C13 through C24 was studied by means of a powder X-ray diffraction method and a linear relation of the longest axis of lattice constant versus number of C atoms was reported (Ogawa & Nakamura, 1999).
In the crystal structure of 1,18-octadecanediol, (I), shown in Fig. 1, an all-trans conformation was observed not only in the hydrocarbon skeleton but also in both terminal hydroxyl groups. The molecule is centrosymmetric and forms a layer structure stacked along c axis. The inclination angle of the long axis of the molecule to the layer plane is equal in each layer, but the direction of the long axis of the molecule is opposite in alternate layers because of an existence of a twofold screw axis parallel to b. Such herring-bone structures can be regarded as a model structure of chiral smectic C liquid crystals. These features are very similar to those of 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol and 1,16-hexadecanediol. Average value of inclination angles of above compounds was about 56° as found in the present structure. These molecules form interlayer hydrogen bonds, as shown in Fig. 2, with the interlayer hydrogen-bonding distance O1···O1i = 2.843 (2) Å [symmetry code: (i) 3 - x, 0.5 + y, 0.5 - z]. This value is in good agreement these of other α,ω-alkanediols with an even number of C atoms.