Joe Schwarcz - Monkeys, Myths, and Molecules: Separating Fact from Fiction, and the Science of Everyday Life

Why Monkeys, Myths and Molecules? Yes, there is a link. And it is meaningful. Let me start my rationale with a question one of my students recently asked. What is the most significant discovery in the history of chemistry? I was really stymied because our knowledge of chemistry is based on a long string of incremental advances and it is unrealistic to label any single discovery as the most significant. There have of course been many momentous discoveries.

We can think of the smelting of metals from their ores, the development of ink, the splitting of the atom and the discoveries of the electron, radioactivity, oxygen and plastics. Daltons theory that elements are made of atoms capable of combining in various ways to form compounds ranks up there, as does Whlers demonstration that chemicals made by living organisms, urea for example, can be produced from non-living substances. Habers synthesis of ammonia led to the mass production of fertilizer that saved countless lives, as did the discovery of penicillin. But fundamental to the practice of chemistry is the understanding of the structure of molecules. So an argument can be made for August Kekuls unraveling of the mystery of molecular structure as ranking at, or near the top, of a list of chemical discoveries. And that discovery was supposedly inspired by a dream! A dream that would lead to some monkey business.

August Kekuls suggestion that the benzene molecule is composed of carbon atoms joined in a ring was a huge contribution to the development of chemistry. Chemists had long known that benzene consisted of six carbons and six hydrogens, but they had no idea how the atoms were arranged in space. Kekuls solution explained benzenes behavior and provided the basis for planning other reactions that would lead to synthesizing novel dyes, drugs and plastics.

Kekul was a dreamer, or at least he said he was. In 1890, at a meeting organized in his honor by the German Chemical Society, he recounted how two dreams had led to his being labeled the principal founder of the theory of molecular structure. The first one, in 1858, resulted in the formulation of the basic theory of how atoms can join together to form molecules. Carbon atoms were said to be tetravalent, meaning they had the ability to form four bonds, nitrogen formed three, oxygen two and hydrogen one. Most importantly, carbon atoms could link to each other, allowing for the possible formation of a huge variety of molecules. Kekul claimed the idea came to him while riding a horse-drawn omnibus in London:

I fell into a reverie, and lo, the atoms were gamboling before my eyes. I saw how, frequently, smaller atoms united to form a pair; how a larger one embraced the two smaller ones; how still larger ones kept hold of three or even four of the smaller; whilst the whole kept whirling in a giddy dance. I saw how the larger ones formed a chain, dragging the smaller ones after them but only at the ends of the chains. The cry of the conductor: Clapham Road awakened me from my dreaming; but I spent part of the night in putting on paper at least sketches of these dream forms. This was the origin of the Structural Theory.

Kekul then went on to describe the more famous incident that supposedly occurred in 1865 in which he realized that the benzene molecule had a ring structure:

I was sitting writing on my textbook but the work did not progress; my thoughts were elsewhere. I turned my chair to the fire and dozed. Again the atoms were gambolling before my eyes. My mental eye, rendered more acute by the repeated visions of the kind, could now distinguish larger structures, of manifold confirmation; long rows, sometimes more closely fitted together; all twining and twisting in snakelike motion. But look! What was that? One of the snakes had seized hold of its own tail, and the form whirled mockingly before my eyes. As if by a flash of lightning I awoke; and this time also I spent the rest of the night in working out the rest of the hypothesis.

We will never know whether the dream stories are historically accurate or whether they represent a form of poetic license used by Kekul to inspire scientists to think outside the proverbial box. Certainly Kekul was not the first to whom the idea of a snake biting its tail occurred. The ouroboros, Greek for tail devourer, is an ancient mystical symbol that clearly depicts a snake engaged in this activity. From the time of the ancient Egyptians, the