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