Friedrich August Kekule
Friedrich August Kekule von Stradonitz was born on September 7th, 1829 in Darmstadt, in the region of Hesse. He wanted to be an architect and went to the University of Giessen with that intention. But, like several other students, he fell under the influence of Justus von Liebig, a famous chemist, after hearing him give evidence in a murder trial. He promptly switched his major.
Once he had his doctorate safely in his hands (1852) he went to Paris and met Charles-FrŽdŽric Gerhardt whose ideas about the structure of organic molecules influenced his own thinking. In 1854 he spent a year as assistant to J. Stenhouse at Saint Bartholomews's Hospital in London and in 1856 he obtained a post (Privatdozent or Lecturer) in the University of Heidelberg, and later became a Professor of Chemistry at Ghent (Belgium) in 1858.
While there he demonstrated that the element carbon must have atoms that could form four bonds, or links, with other atoms, especially other carbon atoms, to form long, long chains. In this he was a co-discoverer with Archibald Scott Couper.
He was not a very practical chemist, and tended to put people to sleep when he lectured, so it was a good job that he was an excellent theorist who advanced the idea that chemical structures were important concepts that could be deduced by the behavior of molecules during chemical reactions. A seriously new idea for his time.
in your sleep
The famous story about Kekule, however, concerns a "dream". This story has been told in various ways, but one version has Kekule falling asleep on a London bus while trying to work out a structure that would explain the peculiar properties of benzene. In this dream either a snake bites its own tail, or a group of six monkeys (imps?) join hands in a circle, but either way Kekule awoke with his answer; benzene was a ring of six carbon atoms! This was the structure that made him well known around the world.
Later in life he carried out a series of investigations on mercury fulminate, unsaturated acids, thio acids and even wrote (but never finished) a very long, four-volume book describing all of organic chemistry - Lehrbuch der Organischen Chemie.
His first wife died in childbirth, and he remarried in 1876. This was not a happy union, despite three children. A serious attack of measles damaged his health so badly that he never properly recovered and after about 1876 he never carried out any more significant work.
He died on July 13th 1896 in the last place he worked, Bonn.