The key difference between cyclohexane and cyclohexene is that the cyclohexane is a saturated hydrocarbon whereas the cyclohexene is an unsaturated hydrocarbon.
There are various types of organic compounds made by joining different elements with carbon atoms. Cyclohexane and cyclohexene are hydrocarbons that consist of only carbon and hydrogen atoms. Hydrocarbons are in two forms as aromatic and aliphatic hydrocarbons. Moreover, we can categorize them as saturated (alkanes) and unsaturated (alkenes and alkynes) hydrocarbons. All the bonds between carbon atoms and hydrogens are single bonds in saturated hydrocarbons while there are double or triple bonds between the carbon atoms in unsaturated forms.
CONTENTS
1. Overview and Key Difference
2. What is Cyclohexane
3. What is Cyclohexene
4. Side by Side Comparison – Cyclohexane vs Cyclohexene in Tabular Form
5. Summary
What is Cyclohexane?
Cyclohexane is a cyclic molecule with the formula of C6H12. This is a cycloalkane. Though it has the similar number of carbons like benzene, cyclohexane is a saturated hydrocarbon. So there are no double bonds or triple bonds between carbon atoms as in benzene. It is a colourless liquid with a mild, sweet odour. We can produce this compound by the reaction between benzene and hydrogen. Since this is a cycloalkane, it less reactive comparatively.
Figure 01: Chair Conformation of Cyclohexane
Cyclohexane is nonpolar and hydrophobic. Therefore, this is useful as a nonpolar solvent in the chemistry laboratory. We consider this compound as the most stable cycloalkane of all because its total ring strain is minimum. Therefore, it produces the least amount of heat when burning compared to other cycloalkanes.
However, it is highly flammable. Cyclohexane does not have a perfect hexagon shape. Therefore, if it is in the hexagonal shape, it would have a considerable torsional strain. To minimize this torsional strain as much as possible, Cyclohexane adopts a three-dimensional chair conformation. At this conformation, carbon atoms are at an angle of 109.5o. Six hydrogen atoms are in the equatorial plane, and the rest of them are in the axial plane. This conformation is the most stable conformation of cyclohexane.
What is Cyclohexene?
Cyclohexene is a cycloalkene with the formula of C6H10. It is nearly similar to cyclohexane, but there is one double bond between two carbon atoms in the ring, which makes it an unsaturated hydrocarbon. Cyclohexene is a colourless liquid, and it has a sharp smell.
Figure 02: The Double Bond between two Carbon Atoms in the Ring Structure of Cyclohexene
Moreover, it is not very stable. When it is exposed to light and air for a longer period, it forms peroxides. We can produce this compound by hydrogenation of benzene until one double bond remains. Apart from that, it is a highly flammable liquid. Since cyclohexene has a double bond, it can undergo reactions that are characteristic of alkenes. For example, with bromine, it’ll undergo electrophilic addition.
What is the Difference Between Cyclohexane and Cyclohexene?
Cycloalkanes are organic compounds having only single covalent bonds between carbon atoms in a ring structure; cyclohexane is a good example. Cycloalkenes, on the other hand, are organic compounds having singles bonds along with one or more double bonds between carbon atoms in the ring structure; cyclohexene is a good example. Therefore, the key difference between cyclohexane and cyclohexene is that the cyclohexane is a saturated hydrocarbon whereas the cyclohexene is an unsaturated hydrocarbon. Another difference between cyclohexane and cyclohexene is that the cyclohexane is relatively stable, thus, is less reactive while the cyclohexene is relatively unstable, thus, can undergo reactions due to the presence of a double bond in the ring structure.
The below infographic tabulates the difference between cyclohexane and cyclohexene as a side by side comparison.
Summary – Cyclohexane vs Cyclohexene
Cyclohexane is a cyclic alkane compound while cyclohexene is a cyclic alkene compound. The key difference between cyclohexane and cyclohexene is that the cyclohexane is a saturated hydrocarbon whereas the cyclohexene is an unsaturated hydrocarbon.
Reference:
1. “Cyclohexane.” Wikipedia, Wikimedia Foundation, 17 Sept. 2018. Available here
2. “Cyclohexene.” Wikipedia, Wikimedia Foundation, 4 Dec. 2017. Available here
Image Courtesy:
1.”Cyclohexane-chair-2D-stereo-skeletal” (Public Domain) via Commons Wikimedia
2.”Cyclohexene for highscool”By すじにくシチュー – Own work, CC0) via Commons Wikimedia