6 September 16

Friedrich August Kekulé was born on 7 September 1829, in Darmstadt, Germany (which happens to be quite close to Pfungstadt, the city where Johann Georg Klöppinger grew up before emigrating to Philadelphia in 1737). Kekulé is regarded as one of the founders of organic chemistry, in the mid-nineteenth century. He is most famous for discovering the "ring" structure of the benzene molecule. The reactions between benzene and nitric acid, and between benzene and halogens (such as chlorine and bromine), gave products whose properties just could not be explained through the ordinary models of carbon atoms bonded in long chains. But August Kekulé reasoned that the carbon atoms might be bonded in a circle or ring, and he gave credit for this fundamental idea in organic chemistry to a dream experience of seeing a snake biting its own tail. So I'm wearing a tie today featuring black and silver circles to honor Kekulé's work!