| cis-Cyclooctene[1] | |
|---|---|
 |
|
| IUPAC name |
(Z)-Cyclooctene
|
| Other names | cis-Cyclooctene |
| Identifiers | |
| CAS number | 931-87-3 |
| PubChem | 638079 |
| SMILES |
C1CCCC=CCC1
|
| Properties | |
| Molecular formula | C8H14 |
| Molar mass | 110.19676 |
| Density | 0.846 g/mL |
| Melting point |
-16 °C |
| Boiling point |
145-146 °C |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
| Infobox references | |
Cyclooctene is a cycloalkene with an eight-membered ring. It can exist as either the cis- or trans-isomer with the cis-isomer normally being the predominant configuration. Cyclooctene is a smaller cycloalkene in which the cis-isomer is stable at room temperature. Its most stable conformer is shaped like a crown ether with alternating equatorial and axial hydrogens very much like the chair conformation of cyclohexane.
trans-Cyclooctene was first synthesized on a preparatory scale by Arthur C. Cope from N,N,N-trimethylcyclooctylammonium iodide in a Hofmann elimination.[2]
Other methods exist where the trans isomer is synthesized from the cis isomer in several synthetic steps. A photochemical method exists for this conversion in just one step:
 |
 |
| cis-Cyclooctene | trans-Cyclooctene |
| (The double bond is not shown here.) | |
Although the cis-trans equilibrium is unfavorable the reaction can be driven to completion by trapping the trans isomer by complexation with silver [3].
References
- ^ cis-Cyclooctene at Sigma-Aldrich
- ^ Arthur C. Cope and Robert D. Bach "trans-Cyclooctene", Organic Syntheses, Coll. Vol. 5, p.315 (1973); Vol. 49, p.39 (1969)
- ^ A Photochemical Synthesis of Functionalized trans-Cyclooctenes Driven by Metal Complexation Maksim Royzen, Glenn P. A. Yap, and Joseph M. Fox J. AM. CHEM. SOC. 2008, 130, 3760-3761 doi:10.1021/ja8001919
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