''cis''-Cyclooctene is a

cycloalkene A cycloalkene or cycloolefin is a type of alkene hydrocarbon which contains a closed ring of carbon Atom, atoms and either one or more double bonds, but has no Aromaticity, aromatic character. Some cycloalkenes, such as cyclobutene and cyclopentene ...

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 Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...

. Cyclooctene is the smallest cycloalkene that can be isolated as both the ''cis''- and ''trans''-

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

. ''cis''-Cyclooctene is shaped like the 8-carbon equivalent chair conformation of cyclohexane.

Uses and reactions

Cyclooctene undergoes ring-opening metathesis polymerization to give polyoctenamers, which are marketed under the name Vestenamer. ''cis''-Cyclooctene (COE) is a substrate known for quite selectively forming the

epoxide In organic chemistry, an epoxide is a cyclic ether () with a three-atom ring. This ring approximates an equilateral triangle, which makes it strained, and hence highly reactive, more so than other ethers. They are produced on a large scale for ...

, as compared to other cycloalkenes, e.g.

cyclohexene Cyclohexene is a hydrocarbon with the formula C6H10. This cycloalkene is a colorless liquid with a sharp smell. It is an intermediate in various industrial processes. Cyclohexene is not very stable upon long term storage with exposure to light a ...

. 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. It is used as an easily displaced

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...

, e.g.

chlorobis(cyclooctene)rhodium dimer Chlorobis(cyclooctene)rhodium dimer is an organorhodium compound with the formula Rh2Cl2(C8H14)4, where C8H14 is ''cis''- cyclooctene. Sometimes abbreviated Rh2Cl2(coe)4, it is a red-brown, air-sensitive solid that is a precursor to many other or ...

and

chlorobis(cyclooctene)iridium dimer Chlorobis(cyclooctene)iridium dimer is an organoiridium compound with the formula Ir2Cl2(C8H14)4, where C8H14 is ''cis''-cyclooctene. Sometimes abbreviated Ir2Cl2(coe)4, it is a yellow, air-sensitive solid that is used as a precursor to many othe ...

References

{{Authority control Cycloalkenes