Cyclooctane

Cyclooctane
Identifiers
CAS number	292-64-8 Y
PubChem	9266
ChemSpider	8909 Y
ChEMBL	CHEMBL452651 Y
Jmol-3D images	Image 1
SMILES C1CCCCCCC1
InChI InChI=1S/C8H16/c1-2-4-6-8-7-5-3-1/h1-8H2 Y Key: WJTCGQSWYFHTAC-UHFFFAOYSA-N Y InChI=1/C8H16/c1-2-4-6-8-7-5-3-1/h1-8H2 Key: WJTCGQSWYFHTAC-UHFFFAOYAO
Properties
Molecular formula	C8H16
Molar mass	112.21 g/mol
Density	0.834 g/cm3
Melting point	14.59 °C
Boiling point	149 °C
Solubility in water	7.90 mg/L
Related compounds
Related cycloalkanes	Cycloheptane
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Cyclooctane is a cycloalkane with the molecular formula (CH₂)₈.^[1] It is a simple colourless hydrocarbon, but it is often a reference compound for saturated eight-membered ring compounds in general.

Conformation

The conformation has been studied extensively using computational methods. Hendrickson noted that "cyclooctane is unquestionably the conformationally most complex cycloalkane owing to the existence of many conformers of comparable energy." The boat-chair conformation I is the most stable form.^[2] This conformation was confirmed by Allinger and co-workers.^[3] The crown conformation^[4] II is slightly less stable. Among the many compounds exhibiting the crown conformation (structure II) is S₈, elemental sulfur.

The boat-chair (I) and crown (II) conformations of cyclooctane

Synthesis and reactions

The main route to cyclooctane derivatives involves the dimerization of butadiene, catalysed by nickel(0) complexes such as nickel bis(cyclooctadiene).^[5] This process affords, among other products, 1,5-cyclooctadiene (COD), which can be hydrogenated. COD is widely used for the preparation of precatalysts for homogeneous catalysis. The activation of these catalysts under H2, produces cyclooctane, which is usually discarded or burnt:

C₈H₁₂ + 2 H₂ → C₈H₁₆

Cyclooctane participates in no reactions except those typical of a other saturated hydrocarbons, combustion and free radical halogenation. Recent work on alkane functionalisation, using peroxides such as dicumyl peroxide, has opened up the chemistry to some extent, allowing for example the introduction of a phenylamino group.^[6]

Amination of cyclooctane by nitrobenzene

References

1. ^ Mackay, Donald (2006). Handbook of Physical-chemical Properties and Environmental Fate for Organic Chemicals. CRC Press. p. 258. ISBN 1566706874. http://books.google.com/?id=wjd-nEugVskC. 
2. ^ Hendrickson, James B. (1967). "Molecular Geometry V. Evaluation of Functions and Conformations of Medium Rings". Journal of the American Chemical Society 89 (26): 7036–7043. doi:10.1021/ja01002a036 
3. ^ Dorofeeva, O.V.; Mastryukov, V.S.; Allinger, N.L.; Almenningen, A. (1985). "The molecular structure and conformation of cyclooctane as determined by electron diffraction and molecular mechanics calculations". The Journal of Physical Chemistry 89 (2): 252–257. doi:10.1021/j100248a015. http://pubs.acs.org/doi/pdf/10.1021/j100248a015. Retrieved 2008-02-05. 
4. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "crown conformation".
5. ^ Thomas Schiffer, Georg Oenbrink “Cyclododecatriene, Cyclooctadiene, and 4-Vinylcyclohexene” in Ullmann’s Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim.doi:10.1002/14356007.a08_205
6. ^ Deng, Guojun; Wenwen Chen, Chao-Jun Li (February 2009). "An Unusual Peroxide-Mediated Amination of Cycloalkanes with Nitroarenes". Advanced synthesis & catalysis 351 (3): 353–356. doi:10.1002/adsc.200800689.