Stereoisomers
Compounds that are enantiomers of each other have the same physical properties, except
for the direction in which they rotate polarized light and how they interact with different
optical isomers of other compounds.
In nature, most biological compounds, such as amino acids, occur as single enantiomers.
As a result, different enantiomers of a compound may have substantially different biological
effects.
Whenamoleculehasmorethanonesourceofasymmetry, twoopticalisomersmaybeneither
perfect reflections of each other nor superimposeable: some but not all stereocenters are
inverted. These molecules are diastereomers, not enantiomers. Diastereomers seldom have
the same physical properties.
Figure 79 The two enantiomers of bromochlorofluoromethane
and their relationship.
Optical isomerism is a form of isomerism (specifically stereoisomerism) where the two dif-
ferent isomers are the same in every way except being non-superposable [1] mirror images
of each other. Optical isomers are known as chiral molecules (pronounced ki-rall).