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Tutorial topics:


Viewing Basics

Molecular Shapes



Substituted Cyclohexane


SN2 Reaction

SN1 Reaction



Conformations of Ethane

In this tutorial, we will learn the relative stability of ethane conformations as a result of single bond rotation. The structure of ethane, C2H6, is shown below. The bond between the two carbon atoms is a single bond which is formed by two sp3 hybrid orbitals overlapping head to head. This symmetric cylindrical electron distribuation allows for "free" rotation around the C-C bond. Shown to the right of this structure are "live" ethane molecules animated to rotate around that bond, with the right one viewed from the left the molecule.

ethane molecule
a single sigma C-C bond

viewed from the top

viewed from the left, with your eye looking down C-C bond

As the C-C bond rotates, an infinite number of conformations (or conformers) is created. The two which are of most interest to us are shown below:

Ethane Conformation A
Rotate Me!

Ethane Conformation A
Rotate Me!

It's now your turn to rotate the two conformers and examine their spatial properties. After that, answer the following two questions:

1) which is of lower energy and thus more stable?
2) What are the names we give to the two conformers? (hint: how are the hydrogens arranged on the front carbon relative to the back carbon?)

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This page was last updated on May 26, 2004 by Dr. Linfeng Xie.
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