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Acta Cryst. (2008). E64, o554    [ doi:10.1107/S1600536808003309 ]

Racemic 4-(4-tert-butylphenyl)-2,6-dimethylcyclohex-3-enecarboxylic acid

S. Xie, C. R. O'Hearn and P. D. Robinson

Abstract top

The chirality of the title compound, C19H26O2, is solely generated by the presence of the double bond in the cyclohexene ring. This compound was synthesized to study the interaction of the two enantiomers in the solid state. The resultant racemate is made up of carboxylic acid RS dimers. Intermolecular O-H...O hydrogen bonds produce centrosymmetric R22(8) rings which dimerize the two chiral enantiomers through their carboxyl groups.

Comment top

The title carboxylic acid, the structure of whose single enantiomer is unknown, was prepared to study the interaction of the two enantiomers in the solid state. We have previously reported the structure of its precursor, which is achiral and also forms hydrogen-bonded dimers (Xie et al., 2007b). The chirality of the title compound is solely generated by the presence of the double bond in the cyclohexene ring (Xie et al., 2004). The resultant racemate is made up of carboxylic acid RS dimers. The structure and atom numbering are shown in Fig. 1, which illustrates the half-chair conformation of the cyclohexene ring. The torsion angles involving atoms C2, C3, C4, C5, and C6 are all near 180°, as are those involving atoms C8, C2, C1, C6, and C9. The carboxyl group is almost perpendicular to the cyclohexene ring with an angle of 81.6 (5) ° between the O1—C7—O2 plane and the C1—C6 ring. The double bond between C3—C4 is not fully conjugated as shown by the C3—C4—C5 plane to benzene ring angle of 30.4 (5) °.

Fig. 2 shows the hydrogen bonding scheme and molecular packing. Atom O2 acts as a donor in an intermolecular hydrogen bond to atom O1. Inversion of this interaction across (1/2, 1/2, 1/2) produces an R22(8) ring (Bernstein et al., 1995), thus creating a hydrogen-bonded RS dimer. There is no evidence to suggest that weak directional interactions interconnect the dimers. Hydrogen bond geometry is given in Table 1.

Related literature top

In similar compounds previously reported (Xie et al., 2002, 2007a), the racemates also consist of carboxylic acid RS dimers. For related literature, see: Xie et al. (2007b, 2004); Bernstein et al. (1995).

Experimental top

The title carboxylic acid was synthesized following a similar method previously reported by Xie et al., 2002. Purified compound was recrystallized from hexane-ethyl acetate as colorless crystals (m.p. 467–468 K).

Refinement top

The rotational orientations of the methyl H atoms were refined by the circular Fourier method available in SHELXL97 (Sheldrick, 2008); the hydroxyl H atom position was determined in a similar manner. All H atoms were treated as riding with C/O—H distances ranging from 0.82 to 0.98 Å and Uiso(H) values equal to 1.5 (hydroxyl and methyl H atoms) or 1.2 times (all other H atoms) Ueq of the parent atom. The crystal diffracted poorly resulting in a relatively low accuracy refinement.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT and SADABS (Bruker, 2005); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: LS in TEXSAN (Molecular Structure Corporation, 1997) and SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. The molecular structure and atom numbering scheme, with displacement ellipsoids drawn at the 50% probablilty level.
[Figure 2] Fig. 2. Molecular packing and hydrogen bonding as viewed down [001]. Dashed lines represent hydrogen bonds. Most H atoms not involved in hydrogen bonding have been omitted to improve clarity. [Symmetry code: (i) -x + 1, -y + 1, -z + 1.]
(RS)-4-(4-tert-butylphenyl)-2,6-dimethylcyclohex-3-enecarboxylic acid top
Crystal data top
C19H26O2F000 = 624
Mr = 286.40Dx = 1.161 Mg m−3
Monoclinic, P21/cMelting point = 467–468 K
Hall symbol: -P 2ybcMo Kα radiation
λ = 0.71069 Å
a = 24.818 (4) ÅCell parameters from 5539 reflections
b = 9.4674 (18) Åθ = 3.3–25.0º
c = 7.0105 (12) ŵ = 0.07 mm−1
β = 95.799 (5)ºT = 100 (2) K
V = 1638.8 (5) Å3Plate, colorless
Z = 40.36 × 0.29 × 0.09 mm
Data collection top
Bruker Kappa-APEXII CCD
diffractometer		2912 independent reflections
Radiation source: X-ray tube2230 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.062
T = 100(2) Kθmax = 25.1º
φ and ω scansθmin = 1.6º
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		h = −29→29
Tmin = 0.793, Tmax = 0.993k = −11→11
24559 measured reflectionsl = −8→8
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.085H-atom parameters constrained
wR(F2) = 0.244  w = 1/[σ2(Fo2) + (0.0701P)2 + 6.4307P]
where P = (Fo2 + 2Fc2)/3
S = 1.15(Δ/σ)max < 0.001
2912 reflectionsΔρmax = 0.36 e Å−3
196 parametersΔρmin = −0.34 e Å−3
Primary atom site location: structure-invariant direct methodsExtinction correction: none
Crystal data top
C19H26O2V = 1638.8 (5) Å3
Mr = 286.40Z = 4
Monoclinic, P21/cMo Kα
a = 24.818 (4) ŵ = 0.07 mm−1
b = 9.4674 (18) ÅT = 100 (2) K
c = 7.0105 (12) Å0.36 × 0.29 × 0.09 mm
β = 95.799 (5)º
Data collection top
Bruker Kappa-APEXII CCD
diffractometer		2912 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		2230 reflections with I > 2σ(I)
Tmin = 0.793, Tmax = 0.993Rint = 0.062
24559 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.085196 parameters
wR(F2) = 0.244H-atom parameters constrained
S = 1.15Δρmax = 0.36 e Å−3
2912 reflectionsΔρmin = −0.34 e Å−3
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.44630 (12)0.4071 (3)0.5431 (5)0.0292 (8)
O20.46014 (12)0.6355 (3)0.6148 (5)0.0292 (8)
H20.48750.62250.56060.044*
C10.38217 (16)0.5270 (4)0.7216 (6)0.0185 (9)
H10.38180.62040.78180.022*
C20.38377 (16)0.4141 (4)0.8808 (6)0.0196 (9)
H2A0.38720.32120.82150.024*
C30.33177 (17)0.4167 (5)0.9728 (6)0.0264 (10)
H30.33210.38141.09670.032*
C40.28418 (16)0.4675 (4)0.8859 (5)0.0169 (9)
C50.28100 (17)0.5288 (5)0.6930 (6)0.0254 (10)
H5A0.27370.62900.70380.030*
H5B0.25010.48720.61750.030*
C60.33030 (16)0.5119 (5)0.5815 (6)0.0201 (9)
H60.32960.41720.52490.024*
C70.43253 (17)0.5160 (5)0.6182 (6)0.0222 (10)
C80.43195 (18)0.4343 (5)1.0310 (6)0.0289 (11)
H8A0.43250.52991.07680.043*
H8B0.46490.41490.97480.043*
H8C0.42880.37081.13610.043*
C90.32793 (19)0.6213 (5)0.4201 (6)0.0295 (11)
H9A0.29490.60960.33770.044*
H9B0.35830.60840.34730.044*
H9C0.32910.71460.47420.044*
C100.23456 (15)0.4701 (4)0.9897 (5)0.0155 (8)
C110.22526 (16)0.3688 (4)1.1286 (6)0.0188 (9)
H110.25010.29611.15430.023*
C120.18002 (16)0.3744 (4)1.2283 (6)0.0193 (9)
H120.17540.30561.31990.023*
C130.14075 (16)0.4812 (4)1.1952 (6)0.0184 (9)
C140.15024 (17)0.5810 (5)1.0570 (6)0.0210 (9)
H140.12530.65361.03100.025*
C150.19560 (16)0.5761 (5)0.9565 (6)0.0208 (9)
H150.20020.64500.86490.025*
C160.09164 (16)0.4845 (4)1.3099 (5)0.0180 (9)
C170.05339 (17)0.6074 (5)1.2524 (6)0.0243 (10)
H17A0.07250.69511.27410.036*
H17B0.02320.60491.32790.036*
H17C0.04050.59941.11900.036*
C180.05936 (17)0.3457 (5)1.2774 (6)0.0254 (10)
H18A0.04730.33581.14360.038*
H18B0.02860.34781.35000.038*
H18C0.08210.26721.31840.038*
C190.11093 (18)0.4982 (5)1.5252 (6)0.0234 (10)
H19A0.13150.41601.56700.035*
H19B0.08010.50651.59670.035*
H19C0.13320.58081.54580.035*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0299 (17)0.0191 (17)0.0421 (19)−0.0048 (14)0.0203 (14)−0.0079 (14)
O20.0269 (18)0.0221 (17)0.0423 (19)−0.0054 (14)0.0215 (15)−0.0045 (14)
C10.021 (2)0.015 (2)0.021 (2)−0.0007 (17)0.0055 (17)−0.0055 (17)
C20.020 (2)0.017 (2)0.023 (2)0.0000 (18)0.0073 (17)0.0010 (17)
C30.026 (2)0.026 (2)0.029 (2)0.004 (2)0.0145 (19)0.0088 (19)
C40.020 (2)0.012 (2)0.019 (2)−0.0038 (17)0.0034 (16)−0.0011 (16)
C50.019 (2)0.036 (3)0.022 (2)−0.007 (2)0.0055 (17)0.0002 (19)
C60.023 (2)0.020 (2)0.018 (2)−0.0015 (18)0.0058 (17)−0.0021 (17)
C70.024 (2)0.020 (2)0.023 (2)−0.0027 (19)0.0079 (18)−0.0017 (18)
C80.028 (2)0.027 (3)0.032 (2)−0.004 (2)0.0022 (19)0.005 (2)
C90.034 (3)0.031 (3)0.025 (2)−0.001 (2)0.0059 (19)0.0080 (19)
C100.0137 (19)0.016 (2)0.0166 (19)−0.0021 (17)0.0015 (15)−0.0039 (16)
C110.018 (2)0.016 (2)0.022 (2)0.0001 (17)0.0020 (16)0.0003 (16)
C120.021 (2)0.018 (2)0.020 (2)−0.0021 (17)0.0074 (16)0.0030 (16)
C130.017 (2)0.016 (2)0.021 (2)−0.0036 (17)−0.0008 (16)−0.0031 (17)
C140.022 (2)0.019 (2)0.022 (2)0.0035 (18)0.0040 (17)0.0032 (17)
C150.021 (2)0.019 (2)0.021 (2)−0.0008 (18)−0.0009 (17)0.0040 (17)
C160.019 (2)0.018 (2)0.018 (2)0.0020 (17)0.0046 (16)0.0004 (16)
C170.020 (2)0.027 (3)0.026 (2)0.0053 (19)0.0032 (17)0.0034 (19)
C180.020 (2)0.026 (2)0.032 (2)−0.0058 (19)0.0082 (18)−0.0069 (19)
C190.023 (2)0.023 (2)0.024 (2)0.0021 (19)0.0011 (17)−0.0031 (18)
Geometric parameters (Å, °) top
O1—C71.222 (5)C2—H2A0.9800
O2—C71.325 (5)C3—H30.9300
C1—C71.510 (5)C5—H5A0.9700
C1—C21.544 (6)C5—H5B0.9700
C1—C61.545 (6)C6—H60.9800
C2—C31.500 (5)C8—H8A0.9600
C2—C81.523 (6)C8—H8B0.9600
C3—C41.361 (6)C8—H8C0.9600
C4—C51.466 (6)C9—H9A0.9600
C4—C101.493 (5)C9—H9B0.9600
C5—C61.525 (5)C9—H9C0.9600
C6—C91.531 (6)C11—H110.9300
C10—C151.397 (6)C12—H120.9300
C10—C111.402 (6)C14—H140.9300
C11—C121.382 (5)C15—H150.9300
C12—C131.407 (6)C17—H17A0.9600
C13—C141.390 (6)C17—H17B0.9600
C13—C161.527 (5)C17—H17C0.9600
C14—C151.388 (6)C18—H18A0.9600
C16—C171.530 (6)C18—H18B0.9600
C16—C191.542 (6)C18—H18C0.9600
C16—C181.544 (6)C19—H19A0.9600
O2—H20.8200C19—H19B0.9600
C1—H10.9800C19—H19C0.9600
C7—C1—C2109.7 (3)C2—C3—H3118.0
C7—C1—C6111.4 (3)C4—C5—H5A108.0
C2—C1—C6110.7 (3)C6—C5—H5A108.0
C3—C2—C8110.5 (4)C4—C5—H5B108.0
C3—C2—C1109.8 (3)C6—C5—H5B108.0
C8—C2—C1112.0 (3)H5A—C5—H5B107.2
C4—C3—C2124.0 (4)C2—C8—H8A109.5
C3—C4—C5121.1 (4)C2—C8—H8B109.5
C3—C4—C10120.6 (4)C2—C8—H8C109.5
C5—C4—C10118.2 (4)H8A—C8—H8B109.5
C4—C5—C6117.4 (4)H8A—C8—H8C109.5
C5—C6—C9109.6 (4)H8B—C8—H8C109.5
C5—C6—C1108.9 (3)C6—C9—H9A109.5
C9—C6—C1112.0 (3)C6—C9—H9B109.5
C5—C6—H6108.8C6—C9—H9C109.5
C9—C6—H6108.8H9A—C9—H9B109.5
C1—C6—H6108.8H9A—C9—H9C109.5
O1—C7—O2123.1 (4)H9B—C9—H9C109.5
O1—C7—C1123.1 (4)C12—C11—H11119.2
O2—C7—C1113.8 (3)C10—C11—H11119.2
C15—C10—C11116.6 (4)C11—C12—H12119.0
C15—C10—C4121.5 (4)C13—C12—H12119.0
C11—C10—C4122.0 (4)C15—C14—H14118.9
C12—C11—C10121.6 (4)C13—C14—H14118.9
C11—C12—C13121.9 (4)C14—C15—H15119.2
C14—C13—C12116.1 (4)C10—C15—H15119.2
C14—C13—C16123.6 (4)C16—C17—H17A109.5
C12—C13—C16120.2 (4)C16—C17—H17B109.5
C15—C14—C13122.3 (4)H17A—C17—H17B109.5
C14—C15—C10121.5 (4)C16—C17—H17C109.5
C13—C16—C17112.5 (3)H17A—C17—H17C109.5
C13—C16—C19109.4 (3)H17B—C17—H17C109.5
C17—C16—C19108.5 (3)C16—C18—H18A109.5
C13—C16—C18109.6 (3)C16—C18—H18B109.5
C17—C16—C18108.0 (3)H18A—C18—H18B109.5
C19—C16—C18108.8 (3)C16—C18—H18C109.5
C7—O2—H2109.5H18A—C18—H18C109.5
C7—C1—H1108.3H18B—C18—H18C109.5
C2—C1—H1108.3C16—C19—H19A109.5
C6—C1—H1108.3C16—C19—H19B109.5
C3—C2—H2A108.1H19A—C19—H19B109.5
C8—C2—H2A108.1C16—C19—H19C109.5
C1—C2—H2A108.1H19A—C19—H19C109.5
C4—C3—H3118.0H19B—C19—H19C109.5
C2—C3—C4—C5−2.0 (7)C3—C4—C10—C15147.3 (4)
C3—C4—C5—C69.7 (6)C5—C4—C10—C15−29.1 (6)
C7—C1—C2—C3−175.2 (4)C3—C4—C10—C11−31.1 (6)
C7—C1—C6—C5−178.2 (4)C5—C4—C10—C11152.6 (4)
C2—C1—C6—C9−179.2 (3)C15—C10—C11—C12−0.4 (6)
C4—C5—C6—C9−160.8 (4)C4—C10—C11—C12178.0 (4)
C6—C1—C2—C8−175.0 (3)C10—C11—C12—C130.4 (6)
C8—C2—C3—C4147.4 (4)C11—C12—C13—C14−0.3 (6)
C6—C1—C2—C3−51.8 (4)C11—C12—C13—C16−179.4 (4)
C7—C1—C2—C861.6 (4)C12—C13—C14—C150.2 (6)
C1—C2—C3—C423.4 (6)C16—C13—C14—C15179.3 (4)
C2—C3—C4—C10−178.2 (4)C13—C14—C15—C10−0.3 (7)
C10—C4—C5—C6−174.0 (4)C11—C10—C15—C140.4 (6)
C4—C5—C6—C1−38.0 (5)C4—C10—C15—C14−178.1 (4)
C2—C1—C6—C559.4 (4)C14—C13—C16—C171.5 (6)
C7—C1—C6—C9−56.8 (5)C12—C13—C16—C17−179.5 (4)
C2—C1—C7—O155.7 (6)C14—C13—C16—C19−119.2 (4)
C6—C1—C7—O1−67.3 (6)C12—C13—C16—C1959.9 (5)
C2—C1—C7—O2−124.9 (4)C14—C13—C16—C18121.7 (4)
C6—C1—C7—O2112.0 (4)C12—C13—C16—C18−59.3 (5)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O1i0.821.882.702 (4)175
Symmetry codes: (i) −x+1, −y+1, −z+1.
Table 1
Selected geometric parameters (Å, °) top
C3—C41.361 (6)C4—C51.466 (6)
C2—C3—C4—C5−2.0 (7)C2—C1—C6—C9−179.2 (3)
C3—C4—C5—C69.7 (6)C4—C5—C6—C9−160.8 (4)
C7—C1—C2—C3−175.2 (4)C6—C1—C2—C8−175.0 (3)
C7—C1—C6—C5−178.2 (4)C8—C2—C3—C4147.4 (4)
Table 2
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O2—H2···O1i0.821.882.702 (4)175
Symmetry codes: (i) −x+1, −y+1, −z+1.
Acknowledgements top

SX and CO are grateful to the departmental fund and Grant-in-aid for Faculty Research from Indiana University Kokomo, as well as a Senior Research Grant from Indiana Academy of Science. The authors thank Professor Nigam P. Rath of the University of Missouri - St. Louis for kindly collecting the low-temperature data set using a diffractometer whose purchase was made possible by funding from the National Science Foundation (CHE-0420497).

references
References top

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