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 more common. Its most stable cis conformer is shaped like a crown ether with alternating equatorial and axial hydrogens very much like the chair conformation of cyclohexane.

cis-Cyclooctene	trans-Cyclooctene
(The double bond is not shown here.)

[edit] Trans-cyclooctene

Trans-cyclooctene is the smallest cycloalkene in which the trans-isomer is stable at room temperature. trans. 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:

Although the cis-trans equilibrium is unfavorable the reaction can be driven to completion by trapping the trans isomer by complexation with silver ^[3].

Another method is by Corey-Winter olefin synthesis starting from (E)-1,2-Cyclooctanediol ^[4]:

[edit] References

v • d • e Cycloalkenes Alkenes Cyclopropene · Cyclobutene · Cyclopentene · Cyclohexene · Cycloheptene · Cyclooctene Dienes Cyclobutadiene · Cyclopentadiene · Cyclohexadiene (1,3-Cyclohexadiene · 1,4-Cyclohexadiene) · Cycloheptadiene · Cyclooctadiene (1,5-Cyclooctadiene)