By Allison Eck
In the mid-1800s, August Kekulé and other German chemists were making great strides in solving puzzles in structural chemistry. One, however, remained unsolved: the structure of the compound benzene. It was a question that Kekulé was again considering as he sat one day in front of the fireplace in his apartment in Ghent, Belgium.
He had had inklings earlier of what benzene might look like, but that day, as he dozed, images hinting at its structure appeared in his mind’s eye. He later wrote that he saw dancing atoms beaded together along an invisible string, “twisting in snake-like motion.” The atoms morphed into an ouroboros: a snake that wrapped itself into a circle, eating its own tail.
The vision was epiphanic. Kekulé realized that benzene’s structure must consist of a ring of carbon atoms, each with a hydrogen atom attached. That revelation would transform scientists’ understanding of biochemistry and allow for advances in many fields, including pharmaceuticals development.