Friedrich August Kekulé was born on September 7, 1829 in Darmstadt, Germany. His family descended from a Czech line of a Bohemian noble family. As a youth his hobbies included hiking, botany, collecting butterflies, and sketching. His friends remembered that he enjoyed the opportunity to debate, had a quick wit and was very amiable. He started his schooling at the Gymnasium in Darmstadt and was a good student with an aptitude for languages, which eventually led to his ability to speak French, Italian, and English, as well as his native German. He also had a talent for drawing and it was his family's intent that he become an architect. Although he had delicate health as a youth, he became a robust, healthy adolescent with an interest in gymnastics by the time he graduated in 1847. He loved dancing and juggling, and was a talented and entertaining mimic.

In the winter of 1847 Kekulé entered the University of Giessen with the intention of studying architecture. It was here that he happened to enroll in a chemistry class under Justus von Liebig. This decision would change his life forever. He became so interested in the material that he wanted to change his course of study to chemistry. He made this decision despite the fact that his family saw no future for him in chemistry. His persistence eventually won their approval and he graduated in 1851. Kekulé then went to Paris to continue work on his doctoral degree. He became the student and friend of Charles Gerhardt and, also, became acquainted with Jean-Baptiste Dumas. It was here that he learned the unitary theory of chemistry, the theory of radicals and Type Theory. He also became interested in the problems of philosophy of chemistry that would concern him all his life.

I had gotten to this point in reviewing my research, when the constant motion of the bus made me drowsy and I drifted into sleep. I found myself dreaming that I was present at the Deutsche Chemische Gesellshaft in Berlin on the occasion of the twenty-fifth anniversary of the Kekulé benzene theory--and I was being given the opportunity to interview the great man! I began to ask him to reflect upon his career since the awarding of his doctorate on June 25, 1852.

QUESTION: Professor, what was your first work after receiving your doctorate?

KEKULÉ: I first worked as an assistant to Adolf von Planta at Reichenau, Switzerland. I was not really happy there. Intellectual stimulation was missing and I was barely making a living doing sundry chemical work such as assaying mineral water. I only stayed there for a year and half. About this time my former teacher, Liebig, recommended me for a position at St. Bartholomew's Hospital in London working with John Stenhouse. This time was a very important one for me.

QUESTION: How was it important for you, Professor Kekulé?

KEKULÉ: Well, I arrived in 1853 and soon met several other former students of Liebig. The one who became a great friend was A. W. Williamson. We had many interesting discussions on chemistry. My friend was working on trying to classify organic compounds by means of structure. Indeed, I believe that our discussions and those I had with another friend, Mueller, influenced my own "vision" --which happened in London and the subsequent elucidation of the tetravalency of carbon and the ability of carbon atoms to form chains.

QUESTION: Can you tell me more about this vision to which you have referred?

KEKULÉ: Surely! Let me read to you the remarks I am about to make to the assembly today:

During my stay in London I resided in Clapham Road....I frequently, however, spent my evenings with my friend Hugo Mueller....We talked of many things but most often of our beloved chemistry. One fine summer evening I was returning by the last bus, riding outside as usual, through the deserted streets of the city....I fell into a reverie, and lo, the atoms were gamboling before my eyes. Whenever, hitherto, these diminutive beings had appeared to me, they had always been in motion. Now, however, I saw how, frequently, two 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 a part of the night in putting on paper at least sketches of these dream forms. This was the origin of the "Structural Theory.(6)

Of course I wasn't ready to publish at that time--dreams need to be practically tested in the real world--but I had the beginnings of my theory.

QUESTION: Dr. Kekulé, what is the next major event that you recall?

KEKULÉ: It seems to me that about 1855 I failed to gain a position at the Polytechnic School of Zurich--my old teacher Liebig would not recommend me. (We never did get on that well together, you know). But, in 1856, at the suggestion of this same man and of Bunsen, I enrolled at the University of Heidelberg to become a privatdocent. I soon passed the necessary exams (yes, I had them too) and began teaching organic chemistry in the summer term. Now you must realize that in those olden days chemistry was still not highly regarded. I received no salary for my work and I had to build my own lecture room and lab at my residence--and with my own funds. Actually, the only reason I was able to do take the position was because my stepbrother Karl was willing to provide some funds. This time was also a happy one for me. It was in this year that I met my first wife.

QUESTION: How did that come about?

KEKULÉ: It seems that Robert Bunsen had designed a gas laboratory burner. The problem was that we only had gas pressure at night and so could not use the burner during the day. I went to see William Drory, manager of the gas works. Not only was I successful at getting day time gas pressure but also at getting an invitation to the Drory home for dinner. It was here that I met Stephanie.

QUESTION: Was this also near the time when you published your theory concerning carbon?

KEKULÉ: Nearly. I published a paper on the tetravalency of carbon in Liebig's journal "Annalen Der Chemie" in 1857 and extended the concept to include the idea that carbon is able to link in chains in 1858. This concept, if I may modestly say so, laid the basis for structural chemistry. I should also mention that Archibald Scott Couper came to the same conclusion as I concerning the tetravalency of carbon. It seems that I got most of the fame but he was undoubtedly very insightful about this.

QUESTION: Did you spend the rest of your career at Heidelberg, then?

KEKULÉ: No. As a matter of fact in this same year of 1858 I was offered the chair of Chemistry at the University of Ghent in Belgium. It was a much better situation for me. I was promised a new lab, designed and equipped to my specifications, and a new classroom. I accepted the post and began to work long and hard hours. Laboratory, lectures, and work on my book "Lehrbuch Organischen Chemie" took up the days and I often spent hours after midnight preparing for the lectures and laboratory work of the next day. I had taken to heart the idea of Liebig that one must ruin one's health to be successful at chemistry.

QUESTION: I seem to recall that it was near that time that you called together a meeting of chemists. Can you tell me more about that?

KEKULÉ: This was an exciting event. I had been concerned for some time about the unresolved questions in chemistry and so initiated the First International Congress of Chemists held at Karlsruhe in 1860. We--many eminent chemists, including such people as Cannizzaro--were attempting to come to some consensus and agree to some common goals. We tried to address questions of nomenclature and definitions of atom, molecule, and equivalency.

QUESTION: And what happened next?

KEKULÉ: Well, the year 1861 saw the publication of my "Lehrbuch" and in 1862 I published the theory of unsaturated carbon compounds. Up to this point I had not accounted for the isomers of carbon compounds. I also married my dear Stephanie in June of this year. In the following May we had a son. He was healthy but Stephanie died only two years later. For the first time in my adult life I found I could not work. Eventually--by about 1864--I was back at my research. It was at this time that I had my second famous dream.

QUESTION: Did that not have something to do with the compound benzene? And what was this second dream like?

KEKULÉ: You are correct. It did concern benzene. Here let me read you my prepared remarks again‹it will give me a chance to rehearse:

During my stay in Ghent, I lived in elegant bachelor quarters in the main thoroughfare. My study, however, faced a narrow side-alley and no daylight penetrated it....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 gamboling before my eyes. This time the smaller groups kept modestly in the background. My mental eye, rendered more acute by the repeated visions of the kind, could now distinguish larger structures of manifold conformation; long rows sometimes more closely fitted together all twining and twisting in snake-like 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 consequences of the hypothesis. (6)

QUESTION: Was this effort successful?

KEKULÉ: Indeed! In 1867--near the time I accepted the chair of chemistry at the University of Bonn in my native Germany--I reported my assistant Koerner's work (and he does deserve the entire credit for the work) in an address to the Royal Academy

Princeton, coming up! I awoke with a start at the bus driver's call. Like the famous Kekulé, I had been lost in reverie. I needed to quickly finish the review of my notes.

Kekulé's oscillation theory of rapidly interchanging double bonds in the benzene ring explained the existence of only one disubstituted derivative in various syntheses--a problem that his earlier conception of the ring structure of benzene did not address. These findings contributed to the synthesis of aromatics and, thus, contributed to the aniline dye industry of 1872. In 1874 Kekulé was offered and refused an appointment to the University of Munich available after the death of Liebig. He recommended that his former student and assistant von Baeyer to the post. After all of his years of hard work, Kekulé's health began to fail. In 1876 he married his former housekeeper. Although she bore him three children, this was not a happy marriage. During this time he contracted measles and never fully recovered. Despite these difficulties, he was elected Rector of the University of Bonn in 1877.

In 1890 came a highpoint in Kekulé's life--the celebration of the twenty-fifth anniversary of the benzene ring theory at the Duetsche Chemische Gesellshaft in Berlin. Here he delivered the paper "Ueber die Konstitutionen de Pyridins" to the general assembly. Reflecting upon his life in a speech at Bonn in 1892, Kekulé attributed his success to both a preoccupation with architecture which enabled him to think about the spatial relationships of groups of atoms and to his extensive travels which enabled him to sort the good from the bad. His major contributions to chemistry were: reiterating the tetravalency of carbon, proposing its ability to form chains, and the establishment of the ring structure of benzene. He was the principal founder of structural organic chemistry.

Kaiser Wilhelm II enobled Kekulé, who added von Stradonitz to his name in 1895. Kekulé died in Bonn in 1896.

As the buildings of Princeton University loomed ahead of me, I was still contemplating this man who was both scientist and dreamer and seemed to hear him say "Let us learn to dream....then perhaps we shall find the truth. But let us beware of publishing our dreams till they have been tested by the waking understanding". Wise words for scientists to live by.

Bibliography

1. Hubert Alyea, "Kekulé von Stradonitz, Friedrich August" in W. D. Halsey and E. Friedman, eds., Collier's Encyclopedia, Vol.14, Macmillan, New York, NY, 1985, p. 15.

2. Isaac Asimov, Asimov's Biographical Encyclopedia of Science and Technology, Doubleday, New York, NY,1982, pp. 446-448.

3. 0.T. Benfey, "Kekulé-Couper Centennial Symposium", Journal of Chemical Education, 1959, 36, pp. 320-321.

4. Jean Gillis, " Kekule von Stradonitz, (Friedrich) August" in C.C.Gillespie, ed, The Dictionary of Scientific Biography, Vol. VII, Charles Scribner's Sons, New York, NY, 1973.

5. Erwin N. Hiebert, "The Experimental Basis of Kekulé's Valence Theory", Journal of Chemical Education, 1959, 36, pp. 321-328.

6. Royston M. Roberts, Serendipidty, Accidental Discoveries in Science, John Wiley and Sons, New York, NY,1989, pp. 75-81.

7. A paper prepared for American Cyanmid to accompany the painting "August Kekulé--Catalyst of the Chemical Revolution" by Jerry Allison. This paper did not list an author but was given to us by Dr. James Bohning at the Beckman Center for the History of Chemistry at the University of Pennsylvania.

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Kekulé Charicature- donated by William Jensen, University of Cincinnati, and may be used for educational purposes only.

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Mary E. Rothermich
Nancy Zipprich

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