Cyclohexane in its chair configuration has a structure which seems quite
complicated to generate, but it can easily be built using VIEWMOL's
molecule builder. First, start VIEWMOL without any parameter
on the command line and press
Cancel in the file selection box
which pops up. You should now have an empty window on your screen. Press the right
mouse button within this window and select
Molecule/New molecule ... from the
pop-up menu. The molecule editor will open up. We start building cyclohexane
by building one of the tetrahedra:
To continue building cyclohexane we have to remember that the torsion
angles among the carbon atoms alternate between gauche and -gauche
which can be determined easily by looking at the Newman projection:
C from the periodic table.
- Click with the left mouse button in VIEWMOL's window. This will
place the first carbon atom at the origin.
- Click with the left mouse button on the first carbon atom. This will
attach the second carbon atom to the first.
- Click with the left mouse button on the second carbon atom. This will
attach the third carbon atom to the second.
H from the periodic table and click twice on the central
carbon atom. The molecule should now look like the left one in
C again and set the default torsion angle to gauche.
- Click on one of the end carbon atoms. Then select
click on the same carbon atom two more times.
- Change the default torsion angle to -gauche and repeat the last
two steps on the just added carbon atom. The molecule should now look
like the one in the middle of the Figure.
- Change the default torsion angle to gauche again and add a carbon
atom and one hydrogen atom to the last carbon atom. The molecule will
now look like the right one in the Figure.
- Change the default torsion angle to trans and add the second
hydrogen atom to the carbon atom added last.
- Now change the default torsion angle to -gauche and add one
hydrogen atom to the next carbon atom in the ring, then change the
default torsion angle to trans and add the second hydrogen atom.
- Finally, complete cyclohexane by adding first a hydrogen with
the default set to trans and than a hydrogen with the default set to
gauche to the next carbon atom in the ring.
Jörg-Rüdiger Hill Fri Oct 31 14:19:21 CET 2003