Kekule’s Dream

By the early 1800s, chemists had devised accurate means of determining the molecular weight of a single molecule.  By the mid-1800s, ringed molecules were all the rage. Six-Carbon chains of hexane could be made to join head to tail in a ring (C6H12) called “cyclohexane.” The molecular “weight” of this molecule would be 84. These things bend and fold up like a chair, but they are less interesting in terms of their impact on living things.

But a funny thing happened on the way to the forum. Some German chemists were reporting a C6H6 compound with a weight of 78. Although the story may be apocryphal, and it is likely other contemporaneous chemists had deduced and published the same structure, German chemist, Auguste Kekule, is credited with having a dream about a snake eating its tail. This required new, “double bonds” in the ring to make it work, and thus was born the whole chemistry of “aromatic rings.”

Add hydroxy groups (OH) to them and you get phenols. Link those together and you get tannins found in wood, wine, and tea. Aromatic compounds are found in your DNA and in all living organisms. They are what makes life possible. And now, they are found in outer space.

Although astronomers have suspected for years that “Polycyclic Aromatic Hydrocarbons” or “PAH” (of which the C6H6 benzene ring is the fundamental unit) were abundant in space, none have been directly observed until recently. Astronomers pointed the Green Bank radio telescope in West Virginia at an interstellar “cloud” 430 light years from earth and observable near the constellation Taurus. There, they found radio signatures of a variety of different PAH molecules. The challenge now is that they are about 100,000 times more concentrated than any astrophysics model has predicted – an example of one discovery leading to a deeper question.

Comets and interstellar debris very likely deposited PAH on the surface of a young earth billions of years ago. Deposit them in the slurry of iron-rich, moist silicate colloidal clay otherwise known as mud, and PAH compounds will form new, more complex organic compounds when bombarded by solar ultraviolet radiation. Bit by bit, God and mother nature built up these things into self-replicating life forms (prokaryotes) that reduce entropy. Slowly, Adam and Eve would emerge from the mud. After all, the bible tells us

And the LORD God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul.”

 Or, we could go in the other direction of an old spiritual, “Swing low, pro-karyote. Comin’ for to carry me home.”  Sorry, I couldn’t resist.


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