skip page navigationOregon State University
Home

CH334

Organic Chemistry

Cyclohexane Conformation

Exams
External Links
Email Dr. Gable


Drawing cyclohexane is an important skill:  it helps teach you to present a two-dimensional image that can correctly and concisely convey 3-dimensional information.

First the ring.  The major conformer for most cyclohexanes is the chair:

To draw this, keep in mind one important rule:
Bonds that are parallel in the real molecule should be drawn parallel in the picture.

Our general goal is to provide an accurate side-on perspective of the ring, so it's useful to make a model and draw bonds in pairs as you see them:

Drawing a chair cyclohexane

You will need to practice this.

Once you have mastered this, the placement of substituents follws relatively easily.

There are two kinds of substituents:  equatorial, in the general plane of the carbons, and axial, oriented perpendicular to this plane.

Axial bonds are easiest to draw:  they are all vertical, and drawn away from the vertex at each carbon position.  There are three "up" and three "down."

Axial cyclohexane bonds
Equatorial bonds need to be drawn parallel to the C-C bonds to which they are parallel in real life:

Equatorial cyclohexane bonds

The chair is the most important form of cyclohexane, but not the only one.  Others are the boat (a high-energy form; rarely seen) and a twist-boat (an intermediate in the ring-flip isomerism between two chair forms):


The boat is pretty easy to draw, but I do not expect you to master drawing the twist-boat.  Neither is a significant component at room temperature.

Conformer
Jmol structure
Twist-boat (+23 kJ/mol, +5.5 kcal/mol)
cyclohexane_TwBoat.pdb
Boat (29 kJ/mol, +6.9 kcal/mol)
cyclohexane_boat.pdb