organic compounds
rac-(1R,2R,4S)-1,2-Dibromo-4-[(1R)-1,2-dibromoethyl]cyclohexane
aBAM Federal Institute for Materials Research and Testing, Department Analytical Chemistry, Reference Materials, Richard-Willstätter-Strasse 11, D-12489 Berlin-Adlershof, Germany
*Correspondence e-mail: franziska.emmerling@bam.de
In the title compound, C8H12Br4, the cyclohexane ring exhibits a chair conformation. The C—Br distances range from 1.964 (6) to 1.985 (5) Å and the C—C distances range from 1.496 (6) to 1.543 (7) Å. Short intermolecular Br⋯Br contacts [3.467 (4) Å] occur in the crystal.
Related literature
The title compound is an environmentally novel brominated flame retardant (Arsenault et al., 2008; de Wit et al., 2010), also known as TBECH, which was recently identified in beluga whales and in the eggs of herring gulls and double-crested cormorants (Tomy et al., 2008; Gauthier et al., 2009). There is relatively little information available concerning the persistence of TBECH in environmental media, its bioaccumulation in food webs and the toxicity of the pure (Rattfelt et al., 2006; Muir et al., 2007; Khalaf et al., 2009; Nyholm et al., 2009, 2010). The Br⋯Br contacts in the can be classified according to Ramasubbu et al. (1986).
Experimental
Crystal data
|
Data collection: SMART (Bruker, 2001); cell SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXTL.
Supporting information
https://doi.org/10.1107/S160053681004763X/sj5056sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681004763X/sj5056Isup2.hkl
In a 2 L two-necked round bottom flask equipped with a thermometer and a 50 ml dropping funnel, 20.1 g (186 mmol) 4-vinylcyclohexene were dissolved in 1000 mL of dichloromethane. Bromine (19.5 ml, 381 mmol) was slowly added through the dropping funnel within 60 min. Light was excluded from the flask and the reaction mixture was stirred for 20 hrs at ambient temperature. Then excess bromine and dichloromethane were removed by rotary evaporation and the white residue was recrystallied from methanol. For single-crystal x-ray crystallography colourless crystals of the title compound were grown by slow solvent evaporation from methanol at ambient temperature in the absence of light.
The C—H hydrogen atoms were located in difference maps and and fixed in their found positions with Uiso(H) = 1.2 of the parent atom Ueq or 1.5 Ueq(Cmethyl).
1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane, also known as tetrabromoethylcyclohexane (TBECH), is a cycloaliphatic brominated flame retardant used as an additive to flammable materials (e.g., polystyrene and polyurethane) to decrease the risk of accidental fire (Arsenault et al. 2008, Tomy et al. 2008, de Wit et al. 2010). Due to the presence of 4 chiral carbons (C1, C2, C4, C5) TBECH can exist as four diastereomeric pairs of enantiomers (Arsenault et al. 2008). The structural differences between these
lead to concomitant variability in physicochemical properties such as hydrophobicity and water solubility, resulting in variable propensities for biological uptake and metabolism. In this respect, the complex of TBECH is a challenge for its trace quantification in relevant environmental matrices and in the food chain. Recently TBECH has been found to bioaccumulate in fish after dietary exposure (Rattfelt et al. 2006, Nyholm et al. 2009) and it was identified as a possible persistent, bioaccumulative and endocrine disrupting organohalogen chemical (Muir et al. 2007, Khalaf et al. 2009). Calculated half-lives of technical TBECH in activated aerobic and anaerobic soil at 20 °C were estimated to be 21 and 23 days, respectively (Nyholm et al. 2010). In the same study much slower degradation was observed during incubation at 8 °C (half-life: 120 days), suggesting that TBECH will persist in temperate climate zones for an extended period. However, the findings of TBECH in a maritime species (beluga whale) (Tomy et al. 2008) as well as seabirds (herring gulls and double-crested cormorants) (Gauthier et al. 2009) were reported for the first time.The molecular structure of the compound and the atom-labeling scheme are shown in Fig 1. The compound crystallises as a racemate. and each molecule is involved in two intermolecular Br···Br contacts [d(Br1-Br2): 3.467 (4)Å] below the sum of their van der Waals radii, which influence the molecular packing and lead to the formation of chains along the b axis. Generally, halogen···halogen contacts C—X···X—C are defined as type I if the C—X···X angle θ1 is equal or nearly equal to the X···X—C angle θ2. If σimeq 180° and σimeq 90°, the contact is defined as type II (Ramasubbu et al. 1986). For the title compound the respective values amount to θ1(C1—Br1···Br2) = 161.2 (2)° and θ1(C2—Br2···Br1) = 137.3 (2)° These values are in acoordance with type I contacts arise as a result of close packing about an inversion center.
The title compound is an environmentally novel brominated flame retardant (Arsenault et al., 2008; de Wit et al., 2010), which was recently identified in beluga whales and in the eggs of herring gulls and double-crested cormorants (Tomy et al., 2008; Gauthier et al., 2009). There is relatively little information available concerning the persistence of TBECH in environmental media, its bioaccumulation in food webs and the toxicity of the pure
(Rattfelt et al., 2006; Muir et al., 2007; Khalaf et al., 2009; Nyholm et al., 2009, 2010). The Br···Br contacts in the can be classified according to Ramasubbu et al. (1986).Data collection: SMART (Bruker, 2001); cell
SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C8H12Br4 | F(000) = 800 |
Mr = 427.82 | Dx = 2.372 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 48 reflections |
a = 9.6163 (14) Å | θ = 2.2–35° |
b = 13.9193 (19) Å | µ = 13.39 mm−1 |
c = 9.6354 (15) Å | T = 294 K |
β = 111.769 (9)° | Block, colourless |
V = 1197.7 (3) Å3 | 0.14 × 0.11 × 0.05 mm |
Z = 4 |
Bruker APEX CCD area-detector diffractometer | 2213 independent reflections |
Radiation source: fine-focus sealed tube | 1471 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.104 |
ω/2θ scans | θmax = 25.4°, θmin = 2.6° |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | h = −11→11 |
Tmin = 0.61, Tmax = 0.72 | k = −16→16 |
20037 measured reflections | l = −11→11 |
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)] = 0.032 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.086 | H-atom parameters constrained |
S = 1.01 | w = 1/[σ2(Fo2) + (0.0411P)2] where P = (Fo2 + 2Fc2)/3 |
2213 reflections | (Δ/σ)max < 0.001 |
109 parameters | Δρmax = 0.74 e Å−3 |
0 restraints | Δρmin = −0.55 e Å−3 |
C8H12Br4 | V = 1197.7 (3) Å3 |
Mr = 427.82 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 9.6163 (14) Å | µ = 13.39 mm−1 |
b = 13.9193 (19) Å | T = 294 K |
c = 9.6354 (15) Å | 0.14 × 0.11 × 0.05 mm |
β = 111.769 (9)° |
Bruker APEX CCD area-detector diffractometer | 2213 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | 1471 reflections with I > 2σ(I) |
Tmin = 0.61, Tmax = 0.72 | Rint = 0.104 |
20037 measured reflections |
R[F2 > 2σ(F2)] = 0.032 | 0 restraints |
wR(F2) = 0.086 | H-atom parameters constrained |
S = 1.01 | Δρmax = 0.74 e Å−3 |
2213 reflections | Δρmin = −0.55 e Å−3 |
109 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Br1 | −0.22923 (7) | 0.01287 (4) | 0.19367 (7) | 0.0611 (2) | |
Br2 | −0.03998 (7) | 0.31412 (4) | 0.35632 (7) | 0.0567 (2) | |
Br3 | 0.29332 (7) | −0.05633 (4) | 0.35758 (7) | 0.0640 (2) | |
Br4 | 0.48396 (8) | 0.23052 (5) | 0.26547 (9) | 0.0742 (2) | |
C1 | −0.1618 (6) | 0.1472 (3) | 0.1927 (6) | 0.0424 (13) | |
H1 | −0.2493 | 0.1896 | 0.1612 | 0.051* | |
C2 | −0.0616 (5) | 0.1722 (3) | 0.3510 (6) | 0.0366 (12) | |
H2 | −0.1122 | 0.1535 | 0.4184 | 0.044* | |
C3 | 0.0879 (5) | 0.1238 (3) | 0.4013 (5) | 0.0377 (12) | |
H3A | 0.0747 | 0.0558 | 0.4150 | 0.045* | |
H3B | 0.1510 | 0.1501 | 0.4972 | 0.045* | |
C4 | 0.1672 (5) | 0.1358 (3) | 0.2906 (5) | 0.0340 (12) | |
H4 | 0.1874 | 0.2045 | 0.2864 | 0.041* | |
C5 | 0.3200 (6) | 0.0841 (4) | 0.3478 (6) | 0.0436 (13) | |
H5 | 0.3768 | 0.1071 | 0.4492 | 0.052* | |
C6 | 0.4170 (6) | 0.0966 (4) | 0.2563 (7) | 0.0596 (16) | |
H6A | 0.3606 | 0.0789 | 0.1532 | 0.072* | |
H6B | 0.5033 | 0.0545 | 0.2945 | 0.072* | |
C7 | 0.0666 (5) | 0.1057 (4) | 0.1343 (5) | 0.0434 (13) | |
H7A | 0.1158 | 0.1201 | 0.0652 | 0.052* | |
H7B | 0.0502 | 0.0369 | 0.1325 | 0.052* | |
C8 | −0.0828 (6) | 0.1569 (4) | 0.0840 (6) | 0.0450 (14) | |
H8A | −0.0671 | 0.2245 | 0.0705 | 0.054* | |
H8B | −0.1469 | 0.1312 | −0.0120 | 0.054* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0576 (4) | 0.0503 (3) | 0.0783 (5) | −0.0152 (3) | 0.0285 (4) | −0.0085 (3) |
Br2 | 0.0605 (4) | 0.0369 (3) | 0.0721 (5) | 0.0061 (3) | 0.0240 (4) | −0.0052 (3) |
Br3 | 0.0600 (4) | 0.0451 (3) | 0.0740 (5) | 0.0157 (3) | 0.0100 (4) | −0.0049 (3) |
Br4 | 0.0771 (5) | 0.0802 (5) | 0.0861 (6) | −0.0076 (4) | 0.0545 (4) | −0.0118 (4) |
C1 | 0.040 (3) | 0.038 (3) | 0.050 (4) | 0.006 (2) | 0.018 (3) | 0.007 (2) |
C2 | 0.036 (3) | 0.037 (3) | 0.040 (3) | 0.003 (2) | 0.018 (3) | 0.001 (2) |
C3 | 0.041 (3) | 0.043 (3) | 0.025 (3) | 0.005 (2) | 0.008 (3) | −0.001 (2) |
C4 | 0.032 (3) | 0.035 (3) | 0.030 (3) | 0.001 (2) | 0.006 (2) | −0.004 (2) |
C5 | 0.035 (3) | 0.047 (3) | 0.045 (4) | 0.003 (2) | 0.010 (3) | −0.011 (3) |
C6 | 0.048 (4) | 0.067 (4) | 0.066 (4) | 0.001 (3) | 0.025 (3) | −0.023 (3) |
C7 | 0.036 (3) | 0.061 (3) | 0.032 (3) | 0.011 (3) | 0.011 (3) | 0.003 (3) |
C8 | 0.042 (3) | 0.056 (3) | 0.034 (3) | 0.004 (3) | 0.010 (3) | 0.005 (3) |
Br1—C1 | 1.980 (5) | C4—C7 | 1.516 (7) |
Br2—C2 | 1.985 (5) | C4—C5 | 1.543 (7) |
Br3—C5 | 1.979 (5) | C4—H4 | 0.9800 |
Br4—C6 | 1.964 (6) | C5—C6 | 1.512 (7) |
C1—C8 | 1.511 (7) | C5—H5 | 0.9800 |
C1—C2 | 1.512 (7) | C6—H6A | 0.9700 |
C1—H1 | 0.9800 | C6—H6B | 0.9700 |
C2—C3 | 1.496 (6) | C7—C8 | 1.513 (7) |
C2—H2 | 0.9800 | C7—H7A | 0.9700 |
C3—C4 | 1.533 (7) | C7—H7B | 0.9700 |
C3—H3A | 0.9700 | C8—H8A | 0.9700 |
C3—H3B | 0.9700 | C8—H8B | 0.9700 |
C8—C1—C2 | 112.5 (4) | C6—C5—C4 | 116.8 (5) |
C8—C1—Br1 | 109.7 (3) | C6—C5—Br3 | 105.1 (3) |
C2—C1—Br1 | 107.5 (3) | C4—C5—Br3 | 110.8 (3) |
C8—C1—H1 | 109.0 | C6—C5—H5 | 108.0 |
C2—C1—H1 | 109.0 | C4—C5—H5 | 108.0 |
Br1—C1—H1 | 109.0 | Br3—C5—H5 | 108.0 |
C3—C2—C1 | 113.5 (4) | C5—C6—Br4 | 110.2 (4) |
C3—C2—Br2 | 111.2 (3) | C5—C6—H6A | 109.6 |
C1—C2—Br2 | 106.1 (3) | Br4—C6—H6A | 109.6 |
C3—C2—H2 | 108.7 | C5—C6—H6B | 109.6 |
C1—C2—H2 | 108.7 | Br4—C6—H6B | 109.6 |
Br2—C2—H2 | 108.7 | H6A—C6—H6B | 108.1 |
C2—C3—C4 | 113.1 (4) | C8—C7—C4 | 111.6 (4) |
C2—C3—H3A | 109.0 | C8—C7—H7A | 109.3 |
C4—C3—H3A | 109.0 | C4—C7—H7A | 109.3 |
C2—C3—H3B | 109.0 | C8—C7—H7B | 109.3 |
C4—C3—H3B | 109.0 | C4—C7—H7B | 109.3 |
H3A—C3—H3B | 107.8 | H7A—C7—H7B | 108.0 |
C7—C4—C3 | 111.2 (4) | C1—C8—C7 | 113.4 (4) |
C7—C4—C5 | 113.5 (4) | C1—C8—H8A | 108.9 |
C3—C4—C5 | 110.8 (4) | C7—C8—H8A | 108.9 |
C7—C4—H4 | 107.0 | C1—C8—H8B | 108.9 |
C3—C4—H4 | 107.0 | C7—C8—H8B | 108.9 |
C5—C4—H4 | 107.0 | H8A—C8—H8B | 107.7 |
C8—C1—C2—C3 | −48.8 (6) | C7—C4—C5—Br3 | −61.2 (5) |
Br1—C1—C2—C3 | 72.1 (4) | C3—C4—C5—Br3 | 64.7 (4) |
C8—C1—C2—Br2 | 73.5 (4) | C4—C5—C6—Br4 | 66.9 (5) |
Br1—C1—C2—Br2 | −165.6 (2) | Br3—C5—C6—Br4 | −170.0 (3) |
C1—C2—C3—C4 | 50.4 (6) | C3—C4—C7—C8 | 53.3 (5) |
Br2—C2—C3—C4 | −69.1 (5) | C5—C4—C7—C8 | 179.0 (4) |
C2—C3—C4—C7 | −52.6 (5) | C2—C1—C8—C7 | 50.4 (6) |
C2—C3—C4—C5 | −179.7 (4) | Br1—C1—C8—C7 | −69.2 (5) |
C7—C4—C5—C6 | 59.0 (6) | C4—C7—C8—C1 | −53.2 (6) |
C3—C4—C5—C6 | −175.1 (4) |
Experimental details
Crystal data | |
Chemical formula | C8H12Br4 |
Mr | 427.82 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 294 |
a, b, c (Å) | 9.6163 (14), 13.9193 (19), 9.6354 (15) |
β (°) | 111.769 (9) |
V (Å3) | 1197.7 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 13.39 |
Crystal size (mm) | 0.14 × 0.11 × 0.05 |
Data collection | |
Diffractometer | Bruker APEX CCD area-detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2001) |
Tmin, Tmax | 0.61, 0.72 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 20037, 2213, 1471 |
Rint | 0.104 |
(sin θ/λ)max (Å−1) | 0.604 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.032, 0.086, 1.01 |
No. of reflections | 2213 |
No. of parameters | 109 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.74, −0.55 |
Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and ORTEPIII (Burnett & Johnson, 1996), SHELXTL (Sheldrick, 2008).
References
Arsenault, G., Lough, A., Marvin, C., McAlees, A., McCrindle, R., MacInnis, G., Pleskach, K., Potter, D., Riddell, N., Sverko, E., Tittlemier, S. & Tomy, G. (2008). Chemosphere, 72, 1163–1170. Web of Science CSD CrossRef PubMed CAS Google Scholar
Bruker (2001). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Burnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA. Google Scholar
Gauthier, L. T., Potter, D., Hebert, C. E. & Letcher, R. J. (2009). Environ. Sci. Technol. 43, 312-317. Web of Science CrossRef PubMed CAS Google Scholar
Khalaf, H., Larsson, A., Berg, H., McCrindle, R., Arsenault, G. & Olsson, P. E. (2009). Environ. Health. Persp. 117, 1853–1859. CrossRef CAS Google Scholar
Muir, D., Howard, P. H. & Meylan, W. (2007). Organohalogen Compd, 69, 1053–1056. Google Scholar
Nyholm, J. R., Lundberg, C. & Andersson, P. L. (2010). Environ. Pollut. 158, 2235–2240. Web of Science CrossRef CAS PubMed Google Scholar
Nyholm, J. R., Norman, A., Norrgren, L., Haglund, P. & Andersson, P. L. (2009). Environ. Toxicol. Chem. 28, 1035–1042. Web of Science CrossRef PubMed CAS Google Scholar
Ramasubbu, N., Parthasarathy, R. & Murrayrust, P. (1986). J. Am. Chem. Soc. 108, 4308–4314. CrossRef CAS Web of Science Google Scholar
Rattfelt, J., Norman, A., Norrgren, L., Haglund, P. & Andersson, P. L. (2006). Organohalogen Compd, 68, 2007–2010. CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tomy, G., Pleskach, K., Arsenault, G., Potter, D., McCrindle, R., Marvin, C., Sverko, E. & Tittlemier, S. (2008). Environ. Sci. Technol. 42, 543–549. Web of Science CrossRef PubMed CAS Google Scholar
Wit, C. A. de, Herzke, D. & Vorkamp, K. (2010). Sci. Total Environ. 408, 2885–2918. Web of Science PubMed 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.
1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane, also known as tetrabromoethylcyclohexane (TBECH), is a cycloaliphatic brominated flame retardant used as an additive to flammable materials (e.g., polystyrene and polyurethane) to decrease the risk of accidental fire (Arsenault et al. 2008, Tomy et al. 2008, de Wit et al. 2010). Due to the presence of 4 chiral carbons (C1, C2, C4, C5) TBECH can exist as four diastereomeric pairs of enantiomers (Arsenault et al. 2008). The structural differences between these stereoisomers lead to concomitant variability in physicochemical properties such as hydrophobicity and water solubility, resulting in variable propensities for biological uptake and metabolism. In this respect, the complex stereoisomerism of TBECH is a challenge for its trace quantification in relevant environmental matrices and in the food chain. Recently TBECH has been found to bioaccumulate in fish after dietary exposure (Rattfelt et al. 2006, Nyholm et al. 2009) and it was identified as a possible persistent, bioaccumulative and endocrine disrupting organohalogen chemical (Muir et al. 2007, Khalaf et al. 2009). Calculated half-lives of technical TBECH in activated aerobic and anaerobic soil at 20 °C were estimated to be 21 and 23 days, respectively (Nyholm et al. 2010). In the same study much slower degradation was observed during incubation at 8 °C (half-life: 120 days), suggesting that TBECH will persist in temperate climate zones for an extended period. However, the findings of TBECH in a maritime species (beluga whale) (Tomy et al. 2008) as well as seabirds (herring gulls and double-crested cormorants) (Gauthier et al. 2009) were reported for the first time.
The molecular structure of the compound and the atom-labeling scheme are shown in Fig 1. The compound crystallises as a racemate. and each molecule is involved in two intermolecular Br···Br contacts [d(Br1-Br2): 3.467 (4)Å] below the sum of their van der Waals radii, which influence the molecular packing and lead to the formation of chains along the b axis. Generally, halogen···halogen contacts C—X···X—C are defined as type I if the C—X···X angle θ1 is equal or nearly equal to the X···X—C angle θ2. If σimeq 180° and σimeq 90°, the contact is defined as type II (Ramasubbu et al. 1986). For the title compound the respective values amount to θ1(C1—Br1···Br2) = 161.2 (2)° and θ1(C2—Br2···Br1) = 137.3 (2)° These values are in acoordance with type I contacts arise as a result of close packing about an inversion center.