165
are delocalized around the ring, and
shared equally between the carbon
atoms, so that the carbon-carbon
bonds are neither single nor double,
but 1.5 (see pp.254–59). It would
take these new ideas from physics
to finally solve the puzzle of the
structure of the benzene molecule.
Dream of inspiration
Kekulé’s report of his dream is
the most cited personal account
of a flash of inspiration in all of
science. It seems that he was in a
hypnagogic state—on the edge of
going to sleep: that state where
realities and imagination slide into
each another. He described it as
Halbschlaf, or half-sleep. In fact he
describes two such reveries: the
first, probably in 1855, on top of a
bus in south London, heading for
Clapham Road. “Atoms fluttered
before my eyes. I had always seen
these tiny particles in motion, but I
had never succeeded in fathoming
the manner of their motion. Today
I saw how frequently two smaller
ones merged into a pair; how
larger ones engulfed two smaller
ones, still larger ones bonded three
and even four of the small ones.”
The second occasion was in his
study in Ghent in Belgium, possibly
inspired by the ancient ouroboros
symbol of a snake biting its own
tail: “The same thing happenedKekulé described the moment that he
formulated his theory of benzene rings
as a dreamlike vision, in which he saw
a snake biting its own tail as in the
ancient symbol of the ouroboros, which
is depicted here as a dragon.
August Kekulé Friedrich August Kekulé, who
called himself August, was
born on September 7, 1829 in
Darmstadt, now in the German
state of Hesse. While at the
University of Giessen, he
abandoned the study of
architecture and switched to
chemistry after hearing the
lectures of Justus von Liebig.
He eventually became professor
of chemistry at Bonn University.
In 1857 and the following
years, Kekulé published a series
of papers on the tetravalence of
carbon, the bonding in simple
organic molecules, and thestructure of benzene, which
made him the principal architect
of the theory of molecular
structure. In 1895, he was
ennobled by Kaiser Wilhelm II,
and became August Kekulé von
Stradonitz. Three of the first
five Nobel prizes in chemistry
were won by his students.Key works1859 Textbook of Organic
Chemistry
1887 The Chemistry of Benzene
Derivatives or Aromatic
SubstancesA CENTURY OF PROGRESS
with the benzene ring theory...
I turned the chair to face the
fireplace and slipped into a
languorous state...atoms fluttered
before my eyes....Long rows,
frequently linked more densely;
everything in motion, winding and
turning like snakes. And lo, what
was that? One of the snakes grabbed
its own tail and the image whirled
mockingly before my eyes.” ■