Leopold Stephen Ruzicka* was born on September 13, 1887, in Vukovar, a small Croatian town on the Danube, somewhat east of its confluence with the Drava. His father, Stjepan Ruzicka, was a cooper; his mother’s maiden name was Ljubica Sever. His great-grandparents included a Czech, from whom the name Ruzicka stems, an Upper Austrian and his wife from Wurtemberg, the other five being Croats. His ancestors were artisans or farmers, who had enjoyed at most a few years of schooling. After the early death of his father in 1891, he returned with his mother to her birthplace, Osijek, on the Drava somewhat west of its junction with the Danube. There he attended the primary school and the classical gymnasium where the Croatian language was used. He was a fairly good pupil in a general way, but really interested only in physics and mathematics. The other subjects, including the purely descriptive sciences, left him cold. There was no chemistry in the curriculum but, nevertheless, he decided to study this subject out of his interest in the composition of natural products.

He wanted to study at the Zurich Polytechnic Institute but found to his dismay that an entrance examination was required not only in chemistry but also in “descriptive geometry”. He decided to go instead to Germany, where anyone with a completed secondary school education was acceptable as a student at a University or Technical Institute without having to undergo additional entrance examinations. He chose the Technische Hochschule at Karlsruhe, where he began his chemical studies in 1906. This step proved to be decisive for his future. Only later did he discover that in Zurich the curriculum, including practical work, was organized on a very rigid basis; still in 1906 attendance at the lectures was or could be checked. In Karlsruhe, on the other hand, there was considerable freedom. He completed his laboratory courses in 1 3 /4 years and then immediately started his doctoral work on ketenes with Professor Staudinger, who was, at 27, only 6 1/2 years older. There were few bureaucratic formalities; he had attended the prescribed lectures neither in chemical technology nor, unfortunately, in physical chemistry and physics.

After two years of research work Ruzicka was a “Dipl. Ing”, and two weeks later “Dr. Ing”. Staudinger appointed him as his assistant, and they together entered the quite unexplored field of the active constituents – named by them pyrethrins – of Dalmatian insect powder, a plant product, toxic to insects and other coldblooded animals. They thus opened a new chapter of alicyclic chemistry, which was then as unfamiliar to Ruzicka as it was to Staudinger.

In October 1912 he followed Staudinger who became Willstätter‘s successor at the newly dubbed “Eidgenössische Technische Hochschule” (ETH, Swiss Federal Institute of Technology) at Zurich. In Switzerland he found not only a second homeland but also a peaceful and convivial environment that brought with it all the conditions for uninterrupted research. In 1917 he acquired Swiss citizenship.

In the previous year he had already started independent work and this decision initiated the most fruitful and happy decade of his life, when he could work at the laboratory bench from morning to night, on problems of his own choosing, with no teaching responsibilities, except one hour weekly from 1918 onward. During the years 1920-1924 he laid the fundaments of all his future work.

For the accomplishment of his Habilitation work (necessary to become a “Privatdozent”) in 1916-1917 he was glad of the support of the oldest perfume manufacturers in the world, Haarman & Reimer, of Holzminden in Germany. The starting-point for their collaboration was the Tiemann formula for drone; the results were the total synthesis of fenchone and the extension and interpretation of the Wagner rearrangement (this term was then introduced by him). After his habilitation in 1918 the firm of Ciba, Basle, became interested in his work on the preparation of quinine-like compounds. With various co-workers, the first synthesis of b-collidine and of linalool, the partial synthesis of pinene, and a series of investigations in the monoterpene field were carried out.

In 1921, the Geneva perfume manufacturers Chuit, Naef & Firmenich, asked him to collaborate with them. By this time the investigations that were to lead to the elucidation of the constitutional formulas of the higher terpenes has already been started. In the perfumery and sesquiterpene domain the total syntheses of nerolidol and farnesol were carried through. The structure of jasmone was established, Tiemann’s irone formula corrected, and synthetic work in these fields undertaken. But by far the most important fruits collected in the perfumery garden were the elucidations of the structures of the naturally occurring musk perfumes, civetone and muscone. Following these discoveries Ruzicka and his co-workers were able to prepare the whole series of alicyclic ketones with 9 to over 30 carbon atoms as ring members, compounds that had previously been believed to be incapable to existence.

Most of the years 1925-1926 he spent with his friends in Geneva. From October 1926 till 1929 he was Professor of Organic Chemistry at the University of Utrecht. Although he was very happy in Holland, he decided to accept the invitation of the ETH to return to Zurich. The main reason for this decision was the strength of the Swiss organic chemical industry, especially its pharmaceutical and perfumery branches, which required the skill and energy of a whole army of chemists with a thorough training in modern organic chemistry. This circumstance was not only a challenge to the teaching and research abilities of the professors; it also encouraged students to acquire the necessary understanding of the theories and methods to equip them for a career in these industries. The three-fold community of professors, students and industry was thus bound together by bonds of common interest.

In 1930, the Ciba renewed the contact with his laboratory. This association led in a few years to scientifically as well as industrially important successes in the field of the male sex hormones. From 1937 the Rockefeller Foundation generously provided financial backing for the research on natural compounds, especially the triterpenes and steroids, free from any special conditions. With the two industries, there was thus formed a strong group of constant supporters of his research team which had grown much in the meantime.

Professor Ruzicka holds eight honorary doctorates (4 Science, 2 Medicine, 1 Natural Sciences, 1 Law) 7 prizes and medals, 24 honorary memberships of chemical, biochemical and other scientific societies, 18 honorary, ordinary and foreign memberships of scientific academies. The circle of his friends is very wide, not only geographically but also spiritually, including the Vatican City as well as Moscow. He feels that the honours which he has won should be distributed among the whole team of his co-workers, and that, to mention only one example, the laudation of his 1936 honorary Doctor diploma of Harvard (tercentenary celebration of the oldest USA university) should more realistically be read in the plural form “… to the team of chemists, daring in their attacks, brilliant in their methods, successful in their interpretations of the architecture of nature’s baffling compounds”, since every member of the team helped to transform the youthful dreams of its oldest member into reality.

Ruzicka married Anna Hausmann in 1912, and Gertrud Acklin in 1951. He has no children, and lives in Zurich. His hobbies are old Dutch and Flemish paintings and alpine plants gardening.

* The pronunciation can be best explained by the French transcription “Rougitchka”.

This autobiography/biography was written at the time of the award and first published in the book series Les Prix Nobel. It was later edited and republished in Nobel Lectures. To cite this document, always state the source as shown above.

Leopold Ruzicka died on September 26, 1976.