Cis-Cyclooctene

<i>cis</i>-Cyclooctene

cis-Cyclooctene

Chemical compound

cis-Cyclooctene is a cycloalkene with the formula (CH2)6(CH)2. It is a colorless liquid that is used industrially to produce a polymer. It is also a ligand in organometallic chemistry.

Quick Facts Names, Identifiers ...

Cyclooctene is the smallest cycloalkene that can be isolated as both the cis- and trans-isomer.[2] cis-Cyclooctene is shaped like the 8-carbon equivalent chair conformation of cyclohexane.

cis-Cyclooctene
in chair conformation		(Rp)-trans-Cyclooctene
in crown conformation

Uses and reactions

Cyclooctene undergoes ring-opening metathesis polymerization to give polyoctenamers, which are marketed under the name Vestenamer.[3]

cis-Cyclooctene (COE) is a substrate known for quite selectively forming the epoxide, as compared to other cycloalkenes, e.g. cyclohexene. Low amounts of radical by-products are found only. This behaviour is attributed to the difficulty of functionalizing allylic CH centers, which almost orthogonal allylic C-H bonds. Therefore, if radicals are around, they tend to form epoxide via an addition-elimination mechanism.[2]

It is used as an easily displaced ligand in organometallic chemistry, e.g. chlorobis(cyclooctene)rhodium dimer and chlorobis(cyclooctene)iridium dimer.

References

  1. [1]
    "cis-Cyclooctene". Sigma-Aldrich.
  2. [2]
    Neuenschwander, Ulrich; Hermans, Ive (2011). "The Conformations of Cyclooctene: Consequences for Epoxidation Chemistry". J. Org. Chem. 76 (24): 10236–10240. doi:10.1021/jo202176j. PMID 22077196.
  3. [3]
    Lionel Delaude; Alfred F. Noels (2005). "Metathesis". Kirk-Othmer Encyclopedia of Chemical Technology. Weinheim: Wiley-VCH. doi:10.1002/0471238961.metanoel.a01. ISBN 0471238961.
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