(b. Vukovar, Slavonia [part of eastern Croatia, now Yugoslavia], 13 September 1887; d. Mammern, Switzerland, 26 September 1976)
structural organic chemistry, biochemistry.
Ružička came from a family of artisans and peasants. His father, Stjepan Ružička, a cooper, died when Leopold was four. He then moved with his mother, Amalija Sever, to Osijek, where he attended the primary school and classical gymnasium. In his youth he considered becoming a priest, but after reading Ernst Haeckel’s Welträtsel he turned to technical subjects. His university education was financed by a life insurance policy left by his father. Ružička was married to Anna Hausmann from 1912 to 1950; after their divorce he married Gertrud Frei Acklin in 1951. He became a Swiss citizen in 1917. Ružička was a member of numerous scientific societies, among them the Swiss Chemical Society, of which he was president from 1936 to 1938. He was a member of the editorial board of Helvetica chimica acta, a joint editor in chief of Ergebnisse der Vitamin-und Hormonforschung and an editor of Experientia.
Ružička graduated in 1910 from the Technische Hochschule in Karlsruhe, earning both his engineering diploma and his doctorate under the supervision of Hermann Staudinger. From 1911 to 1916 he worked on the active constituents of the insecticidal plant Pyrethrum cinerariifoliutn. In 1912 he moved with Staudinger to the Eidgenössische Technische Hochschule (ETH) in Zurich, where he became a Privatdozent in 1918 and titular professor in 1923. During the late 1910’s and early 1920’s, Ružička began to collaborate with the Swiss chemical industry, especially M. Naef et Cie. These associations became very important in the development of his research.
Ružička was interested primarily in the relationship between the physiological properties and the molecular structure of organic natural products. He worked successively on synthetic multimembered rings, higher terpenes, and male sex hormones. He began work on odorants from the animal kingdom. The economically important musk compounds civetone and muskone proved to be macrocyclic ketones. As a result of Adolf von Baeyer’s strain theory, it had been thought that only rings of up to eight members were possible. A method was soon found to synthesize ketones with nine to thirty-four members. In 1926 Ružička moved to Naef’s Geneva laboratories. In that same year he accepted the chair of organic chemistry at the University of Utrecht. In 1929 he moved to the chair of organic and inorganic chemistry at the ETH, where he remained until his retirement.
In 1920 Ružička had begun working on higher terpenes. Through the technique of dehydrogenation using sulfur (and later selenium), and through application of the empirical isoprene rule (viewing terpenes as constructed of isoprene units), he and his co-workers determined the structure of sesquiterpenes, diterpenes, and triterpenes. This work led to study of the terpenoids, in 1934 Ružička and his co-workers achieved a partial synthesis of androsterone, which had been isolated in minute amounts by Adolf Butenandt, and proved its relation to the sterols. In 1935 his collaborator Albert Wettstein achieved a partial synthesis of testosterone. These events led to the production of commercial hormones, establishing the Swiss chemical industry in this field. In 1939, Ružička shared the Nobel Prize in chemistry with Butenandt.
While at the ETH, Ružčka continued to collaborate with industry, both training chemists for industry and acquiring financial support for his department. During World War II he opposed the Nazi regime. Moses Wolf Goldberg and several other Jewish co-workers from his group chose to emigrate to the United States, where they played important roles in the development of the pharmaceutical industry. Ružička was founder and president of the Swiss-Yugoslav Relief Society. As he became more politically involved, the work of his laboratory became less focused on his specific interests and became many-faceted. At this time he also began to collect the seventeenth-century Dutch and Flemish paintings that now form a special collection at the Kunsthaus in Zurich.
In the 1950’s Ružička began to work especially on the biogenesis of terpenes and steroids. Through elucidation of the structure of lanosterol, his coworkers under Oskar Jegar had shown a link between these groups. Ružčka built on this and other contemporary work to develop the biogenetic isoprene rule, which he elaborated in 1953. After 1957, when he retired, he continued to work with his laboratory group and to consult with industry, especially Firmenich et Cie, in Geneva and Sandoz A. G. in Basel.
I. Original Works. For Ružička’s Nobel lecture and biography, see Nobel Lectures: Chemistry, 1922-1941 (New York, 1966), 466-496. His biogenetic isoprene rule appeared as “The Isoprene Rule and the Biogenesis of Terpenic Compounds,” in Experientia, 9 (1953), 357-367; see also his Faraday Lecture, “History of the Isoprene Rule” in Proceedings of the Chemical Society (1959), 341-360. His reminiscences. “In the Borderland Between Bioorganic Chemistry and Biochemistry,” are in Annual Review of Biochemistry, 42 (1973), 1-20.
II. Secondary Literature. A comprehensive biography by Vladimir Prelog, Ružčka’s successor, and Oskar Jegar, head of his triterpene research group, as well as a list of Ružčka’s 582 publications, is in Biographical Memoirs of Fellows of the Royal Society, 26 (1980), 411-501. A short but very useful biography is in Modern Men of Science, II (New York, 1968), 468-470.