69 History of Aromatics
Early in the 19th century, advances in equipment, technique and communications resulted
in chemists discovering and experimenting with novel chemical compounds. In the course
of their investigations they stumbled across a different kind of stable compound with the
molecular formula of C 6 H 6. Unable to visualize what such a compound might look like, the
scientists invented all sorts of models for carbon-to-carbon bonding -- many of which were
not entirely stable -- in order to fit what they had observed to what they expected the C 6 H 6
compound to look like.
Benzene (which is the name that was given to the aromatic compound C 6 H 6 ) is probably
the most common and industrially important aromatic compound in wide use today. It
was discovered in 1825 by Michael Faraday, and its commercial production from coal tar
(and, later on, other natural sources) began in earnest about twenty-five years later. The
structure of benzene emerged during the 1860s, the result of contributions from several
chemists, most famously that of Kekulé^1.
Scientists of the time did not have the benefit of understanding that electrons are capable of
delocalization, so that all carbon atoms could share the sameπ-bond electron configuration
equally. Huckel^2 was the first to apply the new theory of quantum mechanics to clearly
separatingσandπelectrons. He went on to develop a theory ofπelectron bonding for
benzene, which was the first to explain the electronic origins of aromaticity.
1 http://en.wikipedia.org/wiki/Kekul%C3%A9
2 http://en.wikipedia.org/wiki/Erich_Huckel