axial and equatorial hydrogens
| |
The animation below shows cyclohexane ring flipping from one chair-conformation
to another. These two chairs are of course equivalent and energetically the same.
However, we can detect that an interconversion took place if
we look at the substituents, in this case the hydrogens.
We distinguish two sets, coloured orange and yellow.
|
The two sets with different colours are defined as follows:
In one chair conformation, number 1 in the animation above,
all the yellow hydrogen atoms are in what we call
axial positions (parallel to the symmetry axis of the ring),
while all orange hydrogens are equatorial, that is more or less in the plane
of the ring.
In the other chair conformation, number 35 in the plot,
this is exactly the other way around.
As a first excercise, try to confirm this statement by examining the
structure, looking at the animation by stepping through it. You
can rotate the structure using the left mouse button.
Use the navigation buttons, or click on the points in the graph, to display
particular conformations.
We will focus on the maxima and minima in the next exercises.
Also notice that the energy barrier is quite low; interconversion will take
place rapidly at room temperature.
