Naming Conventions
Current Methods
The naming conventions for chemical compounds has evolved because of
the need to have a systematic method for chemists to communicate with
each other about the compounds that they synthesize. At the present
time, two naming conventions coexist: the IUPAC system and the Common
Name system. The latter naming method is still used for mostly
historical reasons, since most people want to use simple names to
refer to compounds that they work with on a regular basis. For
example, water is a lot better than dihydrogen oxide for
everyday use.
Graph Theory Application
The IUPAC system uses something akin to graph theory to specify the
major topological features of molecules. In some cases, the two
conventions are mixed. The following example illustrates this
situation. The four molecules shown below are all dimethyl pyridine
derivatives, but they have been given the common name
lutidine. Although they all have the same chemical formula
(C7H9N), clearly, these molecules are different,
given the notion of graph isomorphism with respect to labeled graphs
(in this case, actual molecules). The numbers in each of the
molecule's' names correspond to the positions where the methyl
(CH3) groups are attached relative to the nitrogen (N),
which is assigned the number one position. As a result of their
different (non-isomorphic) structures, these four molecules interact
with the human sense of smell in quite different ways. The first
structure, 2,6-lutidine, is judged to
have the most horrid smell known to humankind. The other lutidines,
while not pleasant, do not fall into this exclusive category of
sensory extrema.
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2000
Rensselaer Polytechnic Institute. All Rights Reserved.