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Racemic erythro-1,2-diphenyl-1,3-propane­diol, C15H16O2, is a model compound representative of erythro forms of structural elements of the 1,2-diaryl-1,3-propane­diol type in lignins. In the crystal structure, the torsion angle between the bulky phenyl groups is -62.26 (11)°. Strong hydrogen bonds take part in a directed co-operative O-H...O-H...O-H...O-H pattern that is assumed to have a decisive influence on the conformation. This is supported by comparisons with the geometries of related compounds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107001928/sk3092sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107001928/sk3092Isup2.hkl
Contains datablock I

CCDC reference: 641803

Comment top

The stereochemistry of lignin models of the 1,2-diaryl-1,3-propanediol type was investigated in a previous paper (Lundquist & Stomberg, 1987). The crystal structure of one of the compounds examined, erythro-1,2-diphenyl-1,3-propanediol (I), is reported in this paper. Previous reports describe the crystal structures of the related compounds erythro-2-(4-methoxyphenyl)-1-phenyl-1,3-propanediol, (II) (Lundquist & Stomberg, 1987), and erythro-1-(4-benzyloxy-3-methoxyphenyl)-2-(4-hydroxy-3-methoxyphenyl)-1,3-propanediol, (III) (Stomberg et al., 1997). The crystal structure of the tetraacetate, (IV), of another related compound, erythro-bis(4-hydroxy-3-methoxyphenyl)-1,3-propanediol, (VI), has also been determined (Stomberg & Lundquist, 1995). Some results from attempts to determine the crystal structure of the diacetate, (V), of erythro-bis(3,4-dimethoxyphenyl)-1,3-propanediol, (VII) (Li et al., 1993; Aoyama et al., 1995), are reported in this paper. The stereochemistry of threo forms of lignin models of the 1,2-diaryl-1,3-propanediol type is discussed in a recent paper (Stomberg et al., 2006).

Syntheses of the compounds discussed above are described in the literature referred to or in references therein. Syntheses of other erythro forms of lignin models of the 1,2-diaryl-1,3-propanediol type have been published by Parkås et al. (2004) [(VIII)], Li et al. (1994) [(IX)], Ahvonen et al. (1983) [(X)], Li et al. (1996) [(XI)] and Kristersson & Lundquist (1980) [(XII)].

A perspective drawing and the atom-numbering of (I) are shown in Fig. 1. Geometric details of (I) are given in Table 1 in which, for comparison, the corresponding geometric data for the related compounds (II) and (III) are also included.

There are strong O—H···O hydrogen bonds (Fig.2) present in the crystal structure of (I); for geometric details and hydrogen-bond notation, see Table 2. On the first-level graph-set, defined by Bernstein et al. (1995) and Grell et al. (1999), R22(12) rings, formed by hydrogen bonds a between pairs of molecules related by an inversion centre and C(6) chains formed by hydrogen bonds b were identified. On the second-level graph-set, R44(8) directed four-membered cooperative O—H···O—H···O—H···O—H rings formed by hydrogen bonds a and b could be recognized.

Disregarding angles between aromatic ring planes, the corresponding geometric details in (I) and the related compounds (II) and (III) are very similar (Table 1 and Fig. 3). Hydrogen bonding may explain the conformational similarities exhibited by these compounds. The overall patterns are different [an R44(8) ring in (I), a C44(8) chain in (II) and an R66(12) ring in (III)], but there are strong hydrogen bonds involved in directed cooperative O—H···O—H···O—H···O—H patterns in the three compounds. The importance of hydrogen bonding for the conformations of compounds (I)–(III) is supported by the conformations adopted by the acetates (IV) and (V). In these compounds, which lack strong hydrogen bonds, the torsion angles between the aromatic groups are close to 180° [-178.8 (4)° in (IV) (Stomberg & Lundquist, 1995) and -172 (2)° in (V) (this work)], implying that the bulky aromatic groups are almost as far apart as possible. This probably governs the conformations adopted by (IV) and (V).

Related literature top

For related literature, see: Ahvonen et al. (1983); Aoyama et al. (1995); Bernstein et al. (1995); Grell et al. (1999); Kristersson & Lundquist (1980); Li et al. (1993, 1994, 1996); Lundquist & Stomberg (1987); Parkås et al. (2004); Stomberg & Lundquist (1995); Stomberg et al. (1997, 2006).

Experimental top

1,2-Diphenyl-1,3-propanediol, (I), was prepared according to the method of Kristersson & Lundquist (1980). Crystals (m.p. 379–380 K) were obtained from a solution in benzene.

erythro-1,2-Bis(3,4-dimethoxyphenyl)-1,3-propanediol, (VII), and the isomeric threo form were acetylated by treatment with [Which?] anhydride–pyridine (1:1) for 24 h. The diacetate, (V), of compound (VII) was obtained in crystalline form (m.p. 363 K). The crystal structure of (V) was solved, but refinement resulted in residuals too high for publication.

13C NMR spectra [100.6 MHz, solvent CDCl3, reference (CH3)4Si, 300 K, δ, p.p.m.): for (I): 20.8 (CH3CO), 21.0 (CH3CO), 49.8 (H—C—CH2), 55.8–55.9 (4 C, OCH3), 64.7 (CH2), 75.4 (H—C—O), [110.2, 110.9 (2 C), 112.1, 119.7, 121.1, 130.1, 130.8, 148.2, 148.6, 148.8, 148.9], (12 C, aromatic C atoms), 169.8 (CO), 170.7 (CO); for the diacetate, (V), of threo-1,2-bis(3,4-dimethoxyphenyl)-1,3-propanediol: 20.9 (CH3CO), 21.2 (CH3CO), 49.6 (H—C—CH2), 55.8–55.9 (4 C, OCH3), 64.7 (CH2), 76.2 (H—C—O), [110.5, 110.6, 110.9, 112.1, 119.7, 121.2, 130.1, 130.7, 148.1, 148.5 (2 C), 148.7] (12 C, aromatic C atoms), 169.9 (CO), 170.9(CO).

Refinement top

H atoms were constrained to ideal geometry using an appropriate riding model (C—H = 0.95–1.00 Å) and refined isotropically. For the hydroxyl groups, the O—H distances (0.84 Å) and C—O—H angles (109.5°) were kept fixed, while the torsion angles were refined from starting positions based on the circular Fourier synthesis.

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT and SADABS (Sheldrick, 2003); program(s) used to solve structure: SHELXTL (Bruker, 2003); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. A perspective drawing of (I), showing the atom-numbering. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. The hydrogen bonds forming chains of molecules in the b axis direction. H atoms not included in the hydrogen-bonding pattern have been omitted for clarity. For labels and symmetry codes, see Table 2.
[Figure 3] Fig. 3. A projection of the overlaid structures of (I) in red/grey, (II) in blue/black and (III) in green/light grey. H atoms have been omitted for clarity.
rac-erythro-1,2-diphenyl-1,3-propanediol top
Crystal data top
C15H16O2F(000) = 488
Mr = 228.28Dx = 1.216 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 5826 reflections
a = 13.9047 (7) Åθ = 2.5–30.2°
b = 5.4818 (3) ŵ = 0.08 mm1
c = 16.8837 (9) ÅT = 173 K
β = 104.243 (1)°Needle, colourless
V = 1247.36 (11) Å30.64 × 0.08 × 0.06 mm
Z = 4
Data collection top
Siemens SMART CCD area detector
diffractometer
3816 independent reflections
Radiation source: fine-focus sealed tube2877 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.033
ω scansθmax = 30.6°, θmin = 2.2°
Absorption correction: multi-scan
SADABS (Sheldrick, 2003)
h = 1919
Tmin = 0.846, Tmax = 0.995k = 77
19374 measured reflectionsl = 2424
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.045Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.126H atoms treated by a mixture of independent and constrained refinement
S = 1.00 w = 1/[σ2(Fo2) + (0.0677P)2 + 0.2365P]
where P = (Fo2 + 2Fc2)/3
3816 reflections(Δ/σ)max = 0.001
172 parametersΔρmax = 0.39 e Å3
0 restraintsΔρmin = 0.16 e Å3
Crystal data top
C15H16O2V = 1247.36 (11) Å3
Mr = 228.28Z = 4
Monoclinic, P21/nMo Kα radiation
a = 13.9047 (7) ŵ = 0.08 mm1
b = 5.4818 (3) ÅT = 173 K
c = 16.8837 (9) Å0.64 × 0.08 × 0.06 mm
β = 104.243 (1)°
Data collection top
Siemens SMART CCD area detector
diffractometer
3816 independent reflections
Absorption correction: multi-scan
SADABS (Sheldrick, 2003)
2877 reflections with I > 2σ(I)
Tmin = 0.846, Tmax = 0.995Rint = 0.033
19374 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0450 restraints
wR(F2) = 0.126H atoms treated by a mixture of independent and constrained refinement
S = 1.00Δρmax = 0.39 e Å3
3816 reflectionsΔρmin = 0.16 e Å3
172 parameters
Special details top

Experimental. Data were collected at 173 K using a Siemens SMART CCD diffractometer equipped with an LT-2 A cooling device. A full sphere of reciprocal space was scanned by 0.3° steps in ω with a crystal-to-detector distance of 3.97 cm, 60 s per frame. The preliminary orientation matrix was obtained from the first 100 frames using SMART (Bruker, 2003). The collected frames were integrated using the preliminary orientation matrix which was updated every 100 frames. Final cell parameters were obtained by refinement of the position of 5826 reflections with I>10σ(I) after integration of all the frames data using SAINT (Bruker, 2003).

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) top
xyzUiso*/Ueq
O10.09514 (6)0.22146 (15)0.99146 (4)0.02768 (19)
H10.06400.26441.02600.041 (4)*
O20.01966 (6)0.36389 (14)0.90674 (5)0.02613 (18)
H20.05400.48650.92550.049 (5)*
C10.23566 (8)0.0369 (2)1.08856 (6)0.0240 (2)
C20.29633 (9)0.2395 (2)1.09326 (7)0.0328 (3)
H2A0.28260.35811.05090.042 (4)*
C30.37738 (10)0.2700 (3)1.15979 (9)0.0426 (3)
H30.41870.40931.16260.062 (5)*
C40.39794 (10)0.0994 (3)1.22151 (8)0.0442 (3)
H40.45350.12091.26670.056 (5)*
C50.33819 (11)0.1017 (3)1.21778 (8)0.0433 (3)
H50.35220.21931.26040.066 (5)*
C60.25709 (9)0.1330 (2)1.15145 (7)0.0332 (3)
H60.21590.27231.14910.048 (4)*
C70.14662 (7)0.00193 (19)1.01723 (6)0.0228 (2)
H70.09980.11391.03580.023 (3)*
C80.17352 (7)0.12065 (19)0.94247 (6)0.0231 (2)
H80.20950.27570.96200.031 (3)*
C90.07975 (8)0.1914 (2)0.87751 (6)0.0256 (2)
H9A0.04010.04270.85910.028 (3)*
H9B0.09930.26140.82970.029 (3)*
C100.24266 (8)0.0328 (2)0.90658 (6)0.0254 (2)
C110.34348 (9)0.0232 (3)0.92319 (8)0.0362 (3)
H110.36810.16150.95580.043 (4)*
C120.40842 (10)0.1204 (3)0.89269 (9)0.0473 (4)
H120.47690.08030.90460.056 (5)*
C130.37331 (11)0.3218 (3)0.84504 (9)0.0468 (4)
H130.41790.42140.82480.060 (5)*
C140.27383 (11)0.3782 (2)0.82691 (8)0.0390 (3)
H140.24960.51550.79370.055 (5)*
C150.20896 (9)0.2345 (2)0.85717 (7)0.0291 (2)
H150.14030.27420.84400.036 (4)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0285 (4)0.0305 (4)0.0266 (4)0.0101 (3)0.0116 (3)0.0053 (3)
O20.0272 (4)0.0241 (4)0.0285 (4)0.0002 (3)0.0097 (3)0.0014 (3)
C10.0253 (5)0.0257 (5)0.0217 (4)0.0037 (4)0.0073 (4)0.0003 (4)
C20.0317 (6)0.0305 (6)0.0349 (6)0.0017 (5)0.0055 (5)0.0027 (5)
C30.0316 (6)0.0444 (8)0.0488 (7)0.0058 (6)0.0043 (5)0.0090 (6)
C40.0350 (6)0.0560 (9)0.0350 (6)0.0112 (6)0.0038 (5)0.0091 (6)
C50.0515 (8)0.0473 (8)0.0263 (6)0.0132 (6)0.0005 (5)0.0051 (5)
C60.0422 (6)0.0304 (6)0.0260 (5)0.0033 (5)0.0066 (5)0.0039 (4)
C70.0237 (5)0.0229 (5)0.0226 (4)0.0014 (4)0.0073 (4)0.0035 (4)
C80.0242 (5)0.0220 (5)0.0236 (5)0.0031 (4)0.0065 (4)0.0023 (4)
C90.0291 (5)0.0254 (5)0.0227 (5)0.0011 (4)0.0069 (4)0.0025 (4)
C100.0258 (5)0.0280 (5)0.0241 (5)0.0007 (4)0.0097 (4)0.0035 (4)
C110.0275 (5)0.0448 (7)0.0368 (6)0.0018 (5)0.0088 (5)0.0038 (5)
C120.0278 (6)0.0696 (10)0.0477 (8)0.0082 (6)0.0151 (5)0.0121 (7)
C130.0476 (8)0.0564 (9)0.0442 (7)0.0227 (7)0.0261 (6)0.0110 (7)
C140.0543 (8)0.0342 (6)0.0359 (6)0.0094 (6)0.0250 (6)0.0020 (5)
C150.0343 (6)0.0281 (6)0.0293 (5)0.0004 (4)0.0162 (4)0.0008 (4)
Geometric parameters (Å, º) top
O1—C71.4312 (12)C7—H71.0000
O1—H10.8400C8—C101.5120 (14)
O2—C91.4277 (13)C8—C91.5329 (14)
O2—H20.8400C8—H81.0000
C1—C61.3886 (15)C9—H9A0.9900
C1—C21.3851 (16)C9—H9B0.9900
C1—C71.5148 (14)C10—C111.3945 (16)
C2—C31.3917 (17)C10—C151.3950 (16)
C2—H2A0.9500C11—C121.3892 (19)
C3—C41.377 (2)C11—H110.9500
C3—H30.9500C12—C131.382 (2)
C4—C51.373 (2)C12—H120.9500
C4—H40.9500C13—C141.376 (2)
C5—C61.3905 (17)C13—H130.9500
C5—H50.9500C14—C151.3863 (16)
C6—H60.9500C14—H140.9500
C7—C81.5456 (14)C15—H150.9500
C7—O1—H1109.5C9—C8—C7110.90 (8)
C9—O2—H2109.5C10—C8—H8106.8
C6—C1—C2118.74 (11)C9—C8—H8106.8
C6—C1—C7119.56 (10)C7—C8—H8106.8
C2—C1—C7121.69 (10)O2—C9—C8112.79 (8)
C3—C2—C1120.22 (12)O2—C9—H9A109.0
C3—C2—H2A119.9C8—C9—H9A109.0
C1—C2—H2A119.9O2—C9—H9B109.0
C4—C3—C2120.37 (13)C8—C9—H9B109.0
C4—C3—H3119.8H9A—C9—H9B107.8
C2—C3—H3119.8C11—C10—C15117.91 (11)
C3—C4—C5120.01 (12)C11—C10—C8120.24 (10)
C3—C4—H4120.0C15—C10—C8121.84 (9)
C5—C4—H4120.0C12—C11—C10120.90 (13)
C4—C5—C6119.85 (12)C12—C11—H11119.6
C4—C5—H5120.1C10—C11—H11119.6
C6—C5—H5120.1C13—C12—C11119.99 (13)
C5—C6—C1120.81 (12)C13—C12—H12120.0
C5—C6—H6119.6C11—C12—H12120.0
C1—C6—H6119.6C12—C13—C14120.03 (12)
O1—C7—C1111.80 (8)C12—C13—H13120.0
O1—C7—C8108.39 (8)C14—C13—H13120.0
C1—C7—C8113.19 (8)C13—C14—C15120.00 (13)
O1—C7—H7107.8C13—C14—H14120.0
C1—C7—H7107.8C15—C14—H14120.0
C8—C7—H7107.8C14—C15—C10121.16 (11)
C10—C8—C9111.52 (8)C14—C15—H15119.4
C10—C8—C7113.49 (9)C10—C15—H15119.4
C6—C1—C2—C30.33 (17)C1—C7—C8—C9171.29 (9)
C7—C1—C2—C3179.80 (11)C10—C8—C9—O2171.76 (8)
C1—C2—C3—C40.1 (2)C7—C8—C9—O260.71 (11)
C2—C3—C4—C50.2 (2)C9—C8—C10—C11132.16 (11)
C3—C4—C5—C60.2 (2)C7—C8—C10—C11101.72 (12)
C4—C5—C6—C10.11 (19)C9—C8—C10—C1548.63 (13)
C2—C1—C6—C50.36 (17)C7—C8—C10—C1577.49 (12)
C7—C1—C6—C5179.84 (11)C15—C10—C11—C121.20 (18)
C6—C1—C7—O1140.20 (10)C8—C10—C11—C12178.04 (11)
C2—C1—C7—O139.27 (13)C10—C11—C12—C130.1 (2)
C6—C1—C7—C897.06 (12)C11—C12—C13—C140.9 (2)
C2—C1—C7—C883.48 (12)C12—C13—C14—C150.7 (2)
O1—C7—C8—C1062.36 (11)C13—C14—C15—C100.43 (18)
C1—C7—C8—C1062.26 (11)C11—C10—C15—C141.37 (17)
O1—C7—C8—C964.09 (11)C8—C10—C15—C14177.86 (10)

Experimental details

Crystal data
Chemical formulaC15H16O2
Mr228.28
Crystal system, space groupMonoclinic, P21/n
Temperature (K)173
a, b, c (Å)13.9047 (7), 5.4818 (3), 16.8837 (9)
β (°) 104.243 (1)
V3)1247.36 (11)
Z4
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.64 × 0.08 × 0.06
Data collection
DiffractometerSiemens SMART CCD area detector
diffractometer
Absorption correctionMulti-scan
SADABS (Sheldrick, 2003)
Tmin, Tmax0.846, 0.995
No. of measured, independent and
observed [I > 2σ(I)] reflections
19374, 3816, 2877
Rint0.033
(sin θ/λ)max1)0.715
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.045, 0.126, 1.00
No. of reflections3816
No. of parameters172
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.39, 0.16

Computer programs: SMART (Bruker, 2003), SAINT (Bruker, 2003), SAINT and SADABS (Sheldrick, 2003), SHELXTL (Bruker, 2003), SHELXTL, DIAMOND (Brandenburg, 2006).

Hydrogen-bonding geometry (Å, °) top
LabelD—H···AD—HH···AD···AD—H···A
aO1—H1···O2i0.841.902.7317 (10)173
bO2—H2···O1ii0.841.952.7523 (11)158
Symmetry codes: (i) -x, -y, -z+2; (ii) x, y-1, z.
Selected geometric parameters (Å,°) for compound (I), and corresponding data for the related compounds (II) and (III). top
Bond(I)(II)(III)
C1-C71.5148 (14)1.513 (4)1.515 (2)
O1-C71.4312 (12)1.433 (5)1.433 (2)
C7-C81.5456 (14)1.538 (4)1.538 (3)
C8-C91.5329 (14)1.526 (4)1.528 (2)
C8-C101.5120 (14)1.520 (4)1.519 (2)
O2-C91.4277 (13)1.420 (4)1.428 (2)
Angle
C1-C7-C8113.19 (8)112.1 (2)113.22 (14)
C1-C7-O1111.80 (8)111.0 (3)110.52 (16)
O1-C7-C8108.39 (8)110.9 (2)110.83 (13)
C7-C8-C10113.49 (9)116.2 (3)116.68 (16)
C7-C8-C9110.90 (8)110.9 (2)111.36 (14)
C9-C8-C10111.52 (8)109.8 (2)109.12 (13)
C8-C9-O2112.79 (8)113.0 (2)110.31 (14)
Torsion angle*
C1-C7-C8-C10-62.26 (11)-61.2 (4)-49.8 (2)
C1-C7-C8-C9171.29 (8)172.6 (4)-175.98 (15)
O1-C7-C8-C1062.36 (11)63.5 (4)75.04 (17)
O1-C7-C8-C9-64.09 (11)-62.8 (4)-51.1 (2)
O2-C9-C8-C7-60.71 (11)-56.1 (4)-49.5 (2)
O2-C9-C8-C10171.76 (8)174.1 (4)-179.70 (15)
Dihedral angle between
aromatic ring planes44.43 (6)115.2 (2)68.03 (8)
*The enantiomer with an S-configuration at the C atom in the benzyl alcohol group is considered.
 

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