Geometric Isomers
Lack of rotation around carbon-carbon
double bonds has an important
structural implication.
These are not the same. Therefore, they
cannot have the same name.
cis-2-butene
trans-2-butene
If the hydrogens are on the same side it is a
cis configuration. If they are on opposite
sides of the double bond it is a trans
configuration.
Name each:
Cis-2-pentene
1-pentene
Trans-2-pentene
Name it:
C-C-C-C-C=C-C
C H H
5-methyl-cis-2-heptene
Stereoisomers
Molecules of the same molecular structure
that differ only in the arrangement of atoms
in space.
What does this mean?
You need to understand 2 terms:
1. Superimposable
Object is symmetrical - mirror image is no
different then original.
Ex- ball
2. Nonsuperimposable
Mirror image cannot be placed on top of
original
Ex- your hands
Stereoisomers
A chiral carbon is
asymmetrical when it has 4 different
groups.
ex - CHFClBr
Where is the chiral carbon?
C-C-C-C-C-C-C
CC