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.^[1]

<gallery> Image:Cis-cyclooctene3D.png|cis-Cyclooctene Image:Trans-cyclooctene3D.png|trans-Cyclooctene </gallery>

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:

Photochemical trans-cyclooctene synthesis Royzen 2008

Although the cis-trans equilibrium is unfavorable the reaction can be driven to completion by trapping the trans isomer by complexation with silver ^[2].

References

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