Stereoisomers
This is more specifically an example of diastereomerism. These two molecules are stereoiso-
mers because the two carbon atoms cannot be rotated relative to each other, due to the
rigidity caused by the pi bond between them. Therefore, they are not ”superimposeable”
- they are not identical, and cannot take each other’s place. However, the isomers are
not mirror images of one another, so they are not enantiomers; therefore they must be
diastereomers.
Diastereomers usually have different chemical and physical properties and can exhibit dra-
matically different biological activity.
Figure 77 Cis-2-butene