ChemWiki: The Dynamic Chemistry E-textbook > Organic Chemistry >
Chirality > Meso Compounds  Meso Compounds  A meso compound is
superimposed on its mirror image. It is optically inactive
although it contains two or more stereocenters. All meso
compounds are achiral.   In general, a meso compound should
contain two or more identical substituted stereocenters. Also,
it has an internal symmetry plane that divides the compound in
half. These two halves reflect each other by the internal
mirror. The stereochemistry of stereocenters should "cancel
out". What it means here is that when we have an internal plane
that splits the compound into two symmetrical sides, the
stereochemistry of both left and right side should be opposite
to each other, and therefore, result in optically inactive.
Cyclic compounds may also be meso.   If A is a meso compound, it
should have two or more stereocenters, an internal plane, and
the stereochemistry should be R S.    1. Look for an internal
plane, or internal mirror, that lies in bet