In order to view some of the structures for this section, you will need the web "plug-in", "CHIME". If you do not have it already installed, you should be able to download it for free from the linked Website. CHIME is a browser that allows you to visualize and manipulate molecules as 3D structures.  Check here if you don't know how to use Chime.

The same basic ideas of conformational analysis developed for simple alkanes also apply, but some new situations are encountered.
 

Butane: CH₃-CH₂-CH₂-CH₃

In butane it is the rotation about the C2-C3 bond that is of most interest since the relative position of the two methyl groups is important.  This can be seen most easily by rotating the molecule to view it down the C2-C3 bond.  The more important conformations are shown below:
ANTI a staggered conformation with the Me groups at 180o with respect to each other
GAUCHE a staggered conformation with the Me groups at 60o with respect to each other
SYN an eclipsed conformation with the Me groups at 0o with respect to each other
GAUCHE a staggered conformation with the Me groups at 60o with respect to each other

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