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 intermediate in the commercial synthesis of nylon.

Production and uses

Cyclohexene is produced by the partial hydrogenation of benzene, a process developed by the Asahi Chemical company. The main product of the process is cyclohexane because cyclohexene is more easily hydrogenated than benzene.
In the laboratory, it can be prepared by dehydration of cyclohexanol.

Reactions and uses

Benzene is converted to cyclohexylbenzene by acid-catalyzed alkylation with cyclohexene. Cyclohexylbenzene is a precursor to both phenol and cyclohexanone.
Hydration of cyclohexene gives cyclohexanol, which can be dehydrogenated to give cyclohexanone, a precursor to caprolactam.
The oxidative cleavage of cyclohexene gives adipic acid. Hydrogen peroxide is used as the oxidant in the presence of a tungsten catalyst.
1,7-Octadiene is produced by ethenolysis of cyclohexene. Bromination gives 1,2-dibromocyclohexane.

Structure

Cyclohexene is most stable in a half-chair conformation, unlike the preference for a chair form of cyclohexane. One basis for the cyclohexane conformational preference for a chair is that it allows each bond of the ring to adopt a staggered conformation. For cyclohexene, however, the alkene is planar, equivalent to an eclipsed conformation at that bond.