Cyclohexane vs. Cyclohexene — What's the Difference?

Cyclohexane and Cyclohexene are hydrocarbons, both composed of carbon and hydrogen atoms, and they share a similar cyclic structure. Cyclohexane is a saturated hydrocarbon, meaning it has single bonds between the carbon atoms, forming a stable, ring-shaped molecule with the chemical formula C₆H₁₂. Cyclohexene, in contrast, is an unsaturated hydrocarbon, containing a carbon-carbon double bond within the six-carbon ring, resulting in the chemical formula C₆H₁₀.

The presence of a double bond in Cyclohexene means it is more reactive than Cyclohexane. This double bond introduces a point of unsaturation, making Cyclohexene susceptible to reactions that can break this bond, allowing the addition of new atoms or molecules, such as hydrogenation or halogenation reactions. On the other hand, Cyclohexane, with its single bonds, exhibits lower reactivity, and typically undergoes substitution reactions.

In terms of physical properties, Cyclohexane and Cyclohexene differ notably. Cyclohexane is relatively nonpolar and will not mix with polar solvents like water; it has a higher boiling point compared to Cyclohexene due to the increased number of hydrogen atoms. Cyclohexene, being unsaturated and containing a double bond, has a lower boiling point and can participate in reactions with polar molecules more readily than Cyclohexane.

When considering usage and applications, Cyclohexane is often used as a solvent in the laboratory and industrial settings, and as a starting material in the synthesis of various compounds due to its stability. Conversely, the reactivity of Cyclohexene makes it valuable in chemical synthesis as it can undergo a variety of chemical reactions to form diverse compounds, offering utility in the production of polymers, resins, and other chemicals.

In summary, while Cyclohexane is a saturated, stable hydrocarbon used extensively as a solvent and starting material, Cyclohexene is an unsaturated, more reactive hydrocarbon useful in chemical synthesis due to the presence of a carbon-carbon double bond.