organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

1,4-Bis(1,1-di­methyl­prop­yl)-2,5-dimeth­­oxy­benzene

aDepartment of Science Education, Graduate School of Education, Hiroshima University, 1-1-1 Kagamiyama, Higashi–Hiroshima, Hiroshima, Japan
*Correspondence e-mail: kamimo@hiroshima-u.ac.jp

(Received 6 September 2011; accepted 15 September 2011; online 30 September 2011)

The title compound, C18H30O2, was prepared by Friedel–Crafts alkyl­ation of 1,4-dimeth­oxy­benzene with 2-methyl-2-butanol. The complete mol­ecule is generated by the application of a crystallographic centre of inversion. The two meth­oxy groups are oriented in the same plane of the aromatic ring [C—C—O—C torsion angle = 9.14 (16)°]. While one methyl group of the tert-pentyl substituent is coplanar with the benzene ring [C—C—C—C = 0.45 (15)°] and lies towards the less-hindered H atom, the other methyl and ethyl groups are directed to either side of the benzene ring [C—C—C—C torsion angles = 118.78 (12) and 59.11 (14)°, respectively]. In the crystal, the hydro­phobic mol­ecules pack to form a brick-wall-like architecture.

Related literature

For the synthesis of the title compound, see: Polito et al. (2010[Polito, V., Hamann, C. S. & Rhile, I. J. (2010). J. Chem. Educ. 87, 969-967.]) and for the synthesis of the analogous compound, 1,4-di-tert-butyl-2,5-dimeth­oxy­benzene, see: Williamson et al. (2006[Williamson, K. L., Minard, R. & Masters, K. M. (2006). Macroscale and Microscale Organic Experiments, 5th ed., ch. 29, pp. 436-450. Boston: Houghton Mifflin.]). For the unique crystal growth of 1,4-di-tert-butyl-2,5-dimeth­oxy­benzene, see: Blatchly & Hartshorne (1966[Blatchly, J. M. & Hartshorne, N. H. (1966). Trans. Faraday Soc. 62, 512-518.]). For the crystal structure of 1,4-di-tert-butyl-2,5-dimeth­oxy­benzene, see: Rosokha & Kochi (2007[Rosokha, S. V. & Kochi, J. K. (2007). J. Am. Chem. Soc. 129, 3683-3697.]).

[Scheme 1]

Experimental

Crystal data
  • C18H30O2

  • Mr = 278.42

  • Triclinic, [P \overline 1]

  • a = 6.456 (5) Å

  • b = 6.551 (5) Å

  • c = 10.800 (5) Å

  • α = 93.120 (5)°

  • β = 105.950 (5)°

  • γ = 108.460 (5)°

  • V = 411.5 (5) Å3

  • Z = 1

  • Mo Kα radiation

  • μ = 0.07 mm−1

  • T = 90 K

  • 0.4 × 0.2 × 0.1 mm

Data collection
  • Bruker APEXII CCD area-detector diffractometer

  • Absorption correction: empirical (using intensity measurements) (SADABS; Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.972, Tmax = 0.993

  • 2473 measured reflections

  • 1888 independent reflections

  • 1698 reflections with I > 2σ(I)

  • Rint = 0.013

Refinement
  • R[F2 > 2σ(F2)] = 0.042

  • wR(F2) = 0.114

  • S = 1.10

  • 1888 reflections

  • 151 parameters

  • All H-atom parameters refined

  • Δρmax = 0.40 e Å−3

  • Δρmin = −0.22 e Å−3

Data collection: APEX2 (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999[Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Comment top

Electrophilic aromatic substitution is one of the key reactions in organic chemistry. The Friedel-Crafts alkylation of 1,4-dimethoxybenzene with tert-butyl alcohol is a popular introductory organic laboratory experiment to illustrate the features of electrophilic aromatic substitution (Williamson et al., 2006). The product, 1,4-di-tert-butyl-2,5-dimethoxybenzene, (I), has also been reported to exhibit a dramatic change of shape during crystal growth (Blatchly and Hartshorne, 1966). Recently, a synthesis involving electrophilic aromatic substitution coupled with a Wagner-Meerwein rearrangement using 1,4-dimethoxybenzene with 2-methyl-2-butanol was reported (Polito et al., 2010). However, the product, 1,4-bis(1,1-dimethylpropyl)-2,5-dimethoxybenzene (II), has no dramatic crystal growth behaviour. To obtain the perspectives on both development of sophisticated laboratory activity in organic chemistry and the relationship between crystal growth and molecular structure, the X-ray diffraction analysis of the title compound (II) was performed, and the structural features of (I) and (II) discussed in this article. The crystal structure of (I) has already been reported (Rosokha and Kochi, 2007).

Compound (I) crystallizes in the monoclinic space group P21/c. The methoxy groups are inclined at 33.9 (1) ° to the benzene plane. The methyl C—H of the methoxy group points to the adjacent benzene ring in a face-on-edge manner, in which the distance between the methyl carbon and the π-plane is 3.47 (1) Å. The crystal packing exhibits a herringbone structure. Compound (II) crystallizes in the triclinic space group P1 (Fig. 1). The asymmetric unit of (II) contains half a molecule with the complete molecule being generated by a centre of inversion located in the benzene ring. In contrast to (I), the methoxy groups lie on almost the same plane as the benzene ring, where the dihedral angle is 4.9 (1) °. The ethyl chains of two tert-pentyl groups stand to one side of the benzene plane in an anti-orientation, where the dihedral angle is 83.8 (2) °. Since the ethyl chain and methyl group of tert-pentyl group and methoxy group are aggregated by hydrophobic interactions, each molecule is closely arranged in the brick-wall fashion (Fig. 2). Compared to (II) the packing mode of (I) seems to be relatively loose, resulting the expression of dynamic crystal growth of (I).

Related literature top

For the synthesis and an educational use of the title compound, see: Polito et al. (2010). For the synthesis and an educational use of the analogous compound, 1,4-di-tert-butyl-2,5-dimethoxybenzene, see: Williamson et al. (2006). For the unique crystal growth of 1,4-di-tert-butyl-2,5-dimethoxybenzene, see: Blatchly & Hartshorne (1966). For the crystal structure of 1,4-di-tert-butyl-2,5-dimethoxybenzene, see: Rosokha & Kochi (2007).

Experimental top

In a 50-ml Erlenmeyer flask were placed 690 mg (5 mmol) of 1,4-dimethoxybenzene, 1.3 g (1.5 mmol) of 2-methyl-2-butanol, and 1.5 ml of glacial acetic acid. The Erlenmeyer flask was immersed in an ice-water bath to cool the solution below 278 K. Concentrated sulfuric acid (5 ml) was added dropwise into the vigorously stirred reaction mixture so as not to exceed the temperature of 283 K. When all the sulfuric acid was added, the mixture was stirred at room temperature for 10 minutes. The Erlenmeyer flask was immersed again in an ice-water bath, and then a sufficient amount of ice-cold water was added into the reaction mixture to quench the reaction and isolate the product. The white solid was filtered off on a small Büchner funnel and washed with a small amount of ice-cold ethanol. Single crystals were obtained by recrystallization from its ethanol solution; M.pt. 382–383 K. 1H NMR (500 MHz, CDCl3):δ 6.72 (s, 2 H), 3.76 (s, 6 H), 1.77 (q, 4 H), 1.29 (s, 12 H), 0.62 (q, 6 H) p.p.m. IR (KBr): 2962, 2933, 2868, 1506, 1481, 1392, 1369, 1209, 1128, 1041, 865 cm-1. APCI-MS: m/z [M—H]+ = 277.21621.

Refinement top

All H atoms were found in a difference Fourier map and refined isotropically.

Structure description top

Electrophilic aromatic substitution is one of the key reactions in organic chemistry. The Friedel-Crafts alkylation of 1,4-dimethoxybenzene with tert-butyl alcohol is a popular introductory organic laboratory experiment to illustrate the features of electrophilic aromatic substitution (Williamson et al., 2006). The product, 1,4-di-tert-butyl-2,5-dimethoxybenzene, (I), has also been reported to exhibit a dramatic change of shape during crystal growth (Blatchly and Hartshorne, 1966). Recently, a synthesis involving electrophilic aromatic substitution coupled with a Wagner-Meerwein rearrangement using 1,4-dimethoxybenzene with 2-methyl-2-butanol was reported (Polito et al., 2010). However, the product, 1,4-bis(1,1-dimethylpropyl)-2,5-dimethoxybenzene (II), has no dramatic crystal growth behaviour. To obtain the perspectives on both development of sophisticated laboratory activity in organic chemistry and the relationship between crystal growth and molecular structure, the X-ray diffraction analysis of the title compound (II) was performed, and the structural features of (I) and (II) discussed in this article. The crystal structure of (I) has already been reported (Rosokha and Kochi, 2007).

Compound (I) crystallizes in the monoclinic space group P21/c. The methoxy groups are inclined at 33.9 (1) ° to the benzene plane. The methyl C—H of the methoxy group points to the adjacent benzene ring in a face-on-edge manner, in which the distance between the methyl carbon and the π-plane is 3.47 (1) Å. The crystal packing exhibits a herringbone structure. Compound (II) crystallizes in the triclinic space group P1 (Fig. 1). The asymmetric unit of (II) contains half a molecule with the complete molecule being generated by a centre of inversion located in the benzene ring. In contrast to (I), the methoxy groups lie on almost the same plane as the benzene ring, where the dihedral angle is 4.9 (1) °. The ethyl chains of two tert-pentyl groups stand to one side of the benzene plane in an anti-orientation, where the dihedral angle is 83.8 (2) °. Since the ethyl chain and methyl group of tert-pentyl group and methoxy group are aggregated by hydrophobic interactions, each molecule is closely arranged in the brick-wall fashion (Fig. 2). Compared to (II) the packing mode of (I) seems to be relatively loose, resulting the expression of dynamic crystal growth of (I).

For the synthesis and an educational use of the title compound, see: Polito et al. (2010). For the synthesis and an educational use of the analogous compound, 1,4-di-tert-butyl-2,5-dimethoxybenzene, see: Williamson et al. (2006). For the unique crystal growth of 1,4-di-tert-butyl-2,5-dimethoxybenzene, see: Blatchly & Hartshorne (1966). For the crystal structure of 1,4-di-tert-butyl-2,5-dimethoxybenzene, see: Rosokha & Kochi (2007).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: WinGX (Farrugia, 1999) and publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing the atom-numbering scheme and displacement ellipsoids at the 50% probability level for non-H atoms. Atoms marked with i are at the symmetry positions 1 - x, 1 - y, 1 - z.
[Figure 2] Fig. 2. The crystal packing of the title compound showing the brick-wall packing arrangement. All H atoms are omitted for clarity.
1,4-Bis(1,1-dimethylpropyl)-2,5-dimethoxybenzene top
Crystal data top
C18H30O2Z = 1
Mr = 278.42F(000) = 154
Triclinic, P1Dx = 1.123 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71069 Å
a = 6.456 (5) ÅCell parameters from 1654 reflections
b = 6.551 (5) Åθ = 3.3–28.8°
c = 10.800 (5) ŵ = 0.07 mm1
α = 93.120 (5)°T = 90 K
β = 105.950 (5)°Plate, colourless
γ = 108.460 (5)°0.4 × 0.2 × 0.1 mm
V = 411.5 (5) Å3
Data collection top
Bruker APEXII CCD area-detector
diffractometer
1888 independent reflections
Radiation source: fine-focus sealed tube1698 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.013
Detector resolution: 8.333 pixels mm-1θmax = 29.0°, θmin = 2.0°
φ and ω scanh = 85
Absorption correction: empirical (using intensity measurements)
(SADABS; Bruker, 2009)'
k = 88
Tmin = 0.972, Tmax = 0.993l = 1214
2473 measured reflections
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)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.114All H-atom parameters refined
S = 1.10 w = 1/[σ2(Fo2) + (0.0566P)2 + 0.1363P]
where P = (Fo2 + 2Fc2)/3
1888 reflections(Δ/σ)max < 0.001
151 parametersΔρmax = 0.40 e Å3
0 restraintsΔρmin = 0.22 e Å3
Crystal data top
C18H30O2γ = 108.460 (5)°
Mr = 278.42V = 411.5 (5) Å3
Triclinic, P1Z = 1
a = 6.456 (5) ÅMo Kα radiation
b = 6.551 (5) ŵ = 0.07 mm1
c = 10.800 (5) ÅT = 90 K
α = 93.120 (5)°0.4 × 0.2 × 0.1 mm
β = 105.950 (5)°
Data collection top
Bruker APEXII CCD area-detector
diffractometer
1888 independent reflections
Absorption correction: empirical (using intensity measurements)
(SADABS; Bruker, 2009)'
1698 reflections with I > 2σ(I)
Tmin = 0.972, Tmax = 0.993Rint = 0.013
2473 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0420 restraints
wR(F2) = 0.114All H-atom parameters refined
S = 1.10Δρmax = 0.40 e Å3
1888 reflectionsΔρmin = 0.22 e Å3
151 parameters
Special details top

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
C10.66045 (17)0.40800 (16)0.56010 (10)0.0142 (2)
C20.54020 (18)0.34722 (16)0.42749 (10)0.0146 (2)
C30.37620 (17)0.43475 (16)0.36311 (10)0.0134 (2)
C40.24450 (18)0.36052 (16)0.21713 (10)0.0149 (2)
C50.28316 (19)0.55446 (18)0.13993 (10)0.0186 (2)
C60.5309 (2)0.7013 (2)0.16805 (13)0.0273 (3)
C70.3162 (2)0.18507 (18)0.15790 (11)0.0199 (3)
C80.01503 (19)0.25829 (19)0.19763 (11)0.0203 (3)
C90.8811 (2)0.17879 (18)0.54390 (11)0.0191 (2)
O10.81796 (14)0.31572 (13)0.62220 (7)0.0203 (2)
H20.574 (3)0.240 (2)0.3790 (14)0.025 (4)*
H5A0.215 (3)0.492 (2)0.0462 (15)0.023 (4)*
H5B0.196 (2)0.646 (2)0.1572 (14)0.021 (3)*
H6A0.599 (3)0.782 (3)0.2639 (17)0.036 (4)*
H6B0.635 (3)0.615 (3)0.1542 (17)0.037 (4)*
H6C0.544 (3)0.819 (3)0.1069 (16)0.034 (4)*
H7A0.226 (3)0.138 (2)0.0662 (15)0.025 (4)*
H7B0.479 (3)0.238 (3)0.1626 (16)0.030 (4)*
H7C0.286 (2)0.050 (2)0.2014 (14)0.023 (3)*
H8A0.073 (3)0.360 (2)0.2338 (14)0.021 (3)*
H8B0.046 (3)0.123 (3)0.2390 (15)0.028 (4)*
H8C0.097 (3)0.216 (2)0.1031 (15)0.024 (4)*
H9A0.744 (3)0.043 (2)0.5000 (14)0.024 (4)*
H9B1.000 (3)0.144 (2)0.6036 (15)0.027 (4)*
H9C0.940 (2)0.256 (2)0.4774 (14)0.021 (3)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0147 (5)0.0146 (5)0.0137 (5)0.0060 (4)0.0038 (4)0.0032 (4)
C20.0169 (5)0.0136 (5)0.0134 (5)0.0052 (4)0.0052 (4)0.0005 (4)
C30.0140 (5)0.0128 (5)0.0117 (5)0.0025 (4)0.0039 (4)0.0012 (3)
C40.0161 (5)0.0155 (5)0.0113 (5)0.0049 (4)0.0027 (4)0.0001 (4)
C50.0227 (6)0.0191 (5)0.0127 (5)0.0061 (4)0.0046 (4)0.0025 (4)
C60.0246 (6)0.0294 (6)0.0248 (6)0.0034 (5)0.0089 (5)0.0072 (5)
C70.0241 (6)0.0199 (5)0.0138 (5)0.0087 (4)0.0024 (4)0.0029 (4)
C80.0168 (5)0.0222 (6)0.0166 (5)0.0028 (4)0.0020 (4)0.0005 (4)
C90.0215 (5)0.0214 (5)0.0179 (5)0.0129 (4)0.0056 (4)0.0021 (4)
O10.0255 (4)0.0258 (4)0.0137 (4)0.0173 (3)0.0028 (3)0.0007 (3)
Geometric parameters (Å, º) top
C1—O11.3812 (14)C6—H6A1.043 (17)
C1—C21.3941 (15)C6—H6B1.037 (17)
C1—C3i1.4051 (15)C6—H6C1.038 (18)
C2—C31.3988 (16)C7—H7A0.976 (15)
C2—H20.963 (15)C7—H7B0.984 (17)
C3—C1i1.4051 (15)C7—H7C1.012 (16)
C3—C41.5371 (15)C8—H8A0.973 (15)
C4—C71.5376 (16)C8—H8B1.003 (17)
C4—C81.5428 (19)C8—H8C0.990 (15)
C4—C51.5494 (17)C9—O11.4229 (14)
C5—C61.5172 (19)C9—H9A1.014 (16)
C5—H5A0.991 (15)C9—H9B0.955 (16)
C5—H5B0.985 (15)C9—H9C0.992 (15)
O1—C1—C2121.95 (10)H6A—C6—H6B107.7 (13)
O1—C1—C3i117.05 (9)C5—C6—H6C110.9 (9)
C2—C1—C3i121.00 (10)H6A—C6—H6C107.8 (13)
C1—C2—C3122.99 (10)H6B—C6—H6C107.0 (13)
C1—C2—H2117.7 (9)C4—C7—H7A109.6 (9)
C3—C2—H2119.3 (9)C4—C7—H7B112.6 (9)
C2—C3—C1i116.02 (10)H7A—C7—H7B107.7 (13)
C2—C3—C4121.35 (9)C4—C7—H7C112.1 (8)
C1i—C3—C4122.63 (9)H7A—C7—H7C106.2 (12)
C3—C4—C7111.63 (9)H7B—C7—H7C108.4 (12)
C3—C4—C8109.87 (9)C4—C8—H8A111.4 (9)
C7—C4—C8106.83 (9)C4—C8—H8B109.7 (9)
C3—C4—C5111.30 (9)H8A—C8—H8B110.2 (13)
C7—C4—C5108.72 (10)C4—C8—H8C108.6 (9)
C8—C4—C5108.33 (9)H8A—C8—H8C108.9 (12)
C6—C5—C4115.63 (10)H8B—C8—H8C107.9 (13)
C6—C5—H5A110.5 (9)O1—C9—H9A109.7 (9)
C4—C5—H5A106.6 (9)O1—C9—H9B104.8 (9)
C6—C5—H5B107.9 (9)H9A—C9—H9B111.0 (12)
C4—C5—H5B109.7 (9)O1—C9—H9C111.1 (8)
H5A—C5—H5B106.2 (12)H9A—C9—H9C110.1 (12)
C5—C6—H6A111.1 (10)H9B—C9—H9C110.1 (13)
C5—C6—H6B112.1 (10)C1—O1—C9118.00 (9)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC18H30O2
Mr278.42
Crystal system, space groupTriclinic, P1
Temperature (K)90
a, b, c (Å)6.456 (5), 6.551 (5), 10.800 (5)
α, β, γ (°)93.120 (5), 105.950 (5), 108.460 (5)
V3)411.5 (5)
Z1
Radiation typeMo Kα
µ (mm1)0.07
Crystal size (mm)0.4 × 0.2 × 0.1
Data collection
DiffractometerBruker APEXII CCD area-detector
Absorption correctionEmpirical (using intensity measurements)
(SADABS; Bruker, 2009)'
Tmin, Tmax0.972, 0.993
No. of measured, independent and
observed [I > 2σ(I)] reflections
2473, 1888, 1698
Rint0.013
(sin θ/λ)max1)0.682
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.114, 1.10
No. of reflections1888
No. of parameters151
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.40, 0.22

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2008), WinGX (Farrugia, 1999) and publCIF (Westrip, 2010).

 

Acknowledgements

This work was partially supported by a Grant-in-Aid for Young Scientists (B) (grant No. 23700956) and Grant-in-Aid for Scientific Research (C) (grant No. 22300272) from the Japan Society for the Promotion of Science (JSPS). The measurements of X-ray crystallographic, 1H NMR and APCI-MS data were performed at the Natural Science Center for Basic Research and Development (N-BARD), Hiroshima University.

References

First citationAltomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115–119.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationBlatchly, J. M. & Hartshorne, N. H. (1966). Trans. Faraday Soc. 62, 512–518.  CrossRef CAS Web of Science Google Scholar
First citationBruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
First citationMacrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationPolito, V., Hamann, C. S. & Rhile, I. J. (2010). J. Chem. Educ. 87, 969–967.  Web of Science CrossRef CAS Google Scholar
First citationRosokha, S. V. & Kochi, J. K. (2007). J. Am. Chem. Soc. 129, 3683–3697.  Web of Science CSD CrossRef PubMed CAS Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationWilliamson, K. L., Minard, R. & Masters, K. M. (2006). Macroscale and Microscale Organic Experiments, 5th ed., ch. 29, pp. 436–450. Boston: Houghton Mifflin.  Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds