This brief section introduces two separate topics of stereochemistry. First, we see how stereochemistry can be represented using an alternate representation, Fischer Projections. We present a few simple rules for the manipulation of Fischer Projections and present techniques for easily determining whether compounds are enantiomeric or meso.
The second part of this section discusses conformational chirality, which
occurs when a particular conformation of a molecule is chiral. Even
achiral molecules can exhibit conformational chirality. Because the
conformations are generally not isolatable, these molecules are still on average
achiral. However, there are some examples of isolatable conformational
enantiomers that result from molecules not capable of conformational
interconversion. Finally, we give allenes as an example of compounds that
exhibit chirality without containing stereogenic carbons.