''cis''-Cyclooctene is a

cycloalkene In organic chemistry, a cycloalkene or cycloolefin is a type of alkene hydrocarbon which contains a closed Ring (chemistry), ring of carbon atoms and either one or more double bonds, but has no Aromaticity, aromatic character. Some cycloalkenes, ...

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 formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...

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

Uses and reactions

Cyclooctene undergoes

ring-opening metathesis polymerization In polymer chemistry, ring-opening metathesis polymerization (ROMP) is a type of chain-growth polymerization involving olefin metathesis. The reaction is driven by relieving ring strain in cyclic olefins. A variety of heterogeneous and homogene ...

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, where the ether forms a three-atom ring: two atoms of carbon and one atom of oxygen. This triangular structure has substantial ring strain, making epoxides highly reactive, more so than other ...

, as compared to other cycloalkenes, e.g.

cyclohexene Cyclohexene is a hydrocarbon with the formula . It is a cycloalkene. At room temperature, cyclohexene is a colorless liquid with a sharp odor. Among its uses, it is an chemical intermediate, intermediate in the commercial synthesis of nylon. Prod ...

. 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 with a 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 el ...

, e.g. chlorobis(cyclooctene)rhodium dimer 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