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Obituary fascinated by the spatial forms of organic Vladimir Prelog (1906-98) molecules. One of his early feats in Zagreb was the synthesis of adamantane, with its POPPERFOTO Pioneer of stereochemistry highly symmetrical molecular structure. Later, in Zürich, he was one of the first to Until quite recently, the nonagenarian see the importance of steric effects on the Vladimir Prelog was a familiar figure in reactivity of molecules with medium and the chemistry building of the ETH. large ring systems — for example, the non- 8 Conspicuous in his immaculate, white reactivity of cyclodecanone towards laboratory coat, he could be seen in the hydrogen cyanide compared with the ready corridors or in the Chemiebar, where he formation of cyanhydrins of smaller and drank his coffee most mornings and larger rings. This led him to afternoons. New students used to ask: conformational analysis, and indeed, “Who is that elderly gentleman in the together with D. H. R. Barton, he was one white lab coat? Is he a laboratory of the founders of this important branch of technician?” On being told that this was modern chemistry. A feature of his later Prelog, the Nobel prizewinner, they were Prelog became head of the laboratory but work was the emphasis on steric bulk as a impressed, for they knew his name from soon decided to share his powers, and his factor in controlling the course of the first-year lectures. We shall see him no responsibilities, with his younger asymmetric synthesis and as a basis for more. Vladimir Prelog, one of the great colleagues — this was then in continental understanding stereospecific reactions in organic chemists of our century, died on 7 Europe a mildly revolutionary step for the general. January after a short illness. He is survived director of a chemistry institute. After his In the mid-1950s, these interests led by his wife and son. retirement in 1976 Prelog promptly Prelog to develop, together with his British A child of the old Austro-Hungarian registered as a special student (Fachhörer) colleagues R. S. Cahn (then editor of The empire, Prelog was born in Sarajevo on 23 in order to continue his scientific work. At Chemical Society) and C. K. Ingold, the July 1906. He was present at the fateful visit the ETH this is not regarded as an now universally adopted ‘CIP’ system of of the Austrian crown prince, Archduke automatic perquisite of a retired professor; rules for specifying the sense of chirality at Franz Ferdinand, on 28 June 1914, when, it is a privilege for which one may be tetrahedral stereogenic centres. Towards waiting to throw flowers in front of the grateful. Prelog’s 1991 autobiographical the end of his life, Prelog was preoccupied state carriage, he heard the shots that sketch was entitled, “My 132 Semesters of with the complexities inherent in this presaged the end of that era. His school Chemistry Studies”. Renowned as teacher system. There can be few organic chemists years were passed in Zagreb, after which he and researcher, he regarded himself as a of his generation who have had the studied chemistry at the Prague Institute student to the end. intellectual strength to master the more of Technology, obtaining his doctorate in As an organic chemist, Prelog bridged mathematical, graph-theoretical aspects of 1929 with Emil Votoc˘ek but being the gap between the classical tradition and the models they use to describe molecular influenced more by Rudolf Lukes˘, who led the modern school. When he began his structures and their interconversions. him into the chemical world of alkaloids. It long research career, molecular structure Not only as a chemist but also as a was the time of the great depression, and was still being inferred by classical person, Prelog made a powerful Prelog supported himself ‘semi-legally’ by methods, that is to say, by subtle but impression on others. He was admired as a preparing chemicals in a commercial indirect arguments from chemical scientist and loved as a person by a laboratory whose owner and director reactivity. Success in this area required multitude of friends from all over the became Prelog’s first doctoral student. In profound knowledge of chemistry, world. A formidable lecturer and talker in 1935 he moved back to Zagreb, where he rigorous logic and, sometimes, a flight of general, renowned for his inexhaustible taught at the university, first as lecturer inspiration as well. By mid-century, supply of jokes, Yugoslavian folk-sayings, and then as professor. Meanwhile, he was physical methods — molecular and anecdotes about every famous chemist associated with a fledgling chemical spectroscopy, X-ray analysis and, later, who has ever lived, he captivated all. company in Zagreb (which later developed nuclear magnetic resonance — were Ambitious as far as science was concerned, into Pliva, the largest Yugoslav beginning to displace the traditional he was uninterested in the exercise of pharmaceutical company). His commercial chemical methods. Prelog’s early work on power — he said that he disliked making preparation of sulphanilamide (Streptazol) the structure of alkaloids from Cinchona, decisions that affected other people. He brought the financial support needed for Strychnos and other sources was done by was seldom provoked to anger and claimed his research. classical methods, whereas his later studies to have an unusually low adrenaline level. In 1941, after the German occupation of metabolic products of microorganisms But, of course, behind this outward of Yugoslavia, he managed to escape under were largely based on the newer physical appearance there was a serious, adventurous circumstances to Zürich in methods. It was mainly through his introspective side. His ironic and often neutral Switzerland. There, at the organic influence that organic chemistry at the self-deprecatory humour was frequently a chemistry laboratory of the Federal ETH was swift to take advantage of the new protective wall for his inner self. Sadly, his Institute of Technology (ETH) under his techniques. last years were clouded by the tragic course fellow countryman Leopold Ruzicka, he For his contributions to of events in his native land, which caused found a temporary refuge, which gradually stereochemistry, Prelog shared the 1975 him immeasurable grief and sadness. developed into a home in every sense of the Nobel prize in chemistry with J. W. Jack D. Dunitz word. If the ETH gave Prelog a home, Cornforth. Stereochemistry is not so much Jack D. Dunitz is in the Organic Chemistry Prelog brought fame to the ETH, with a branch of chemistry as a way of looking Laboratory, Swiss Federal Institute of Technology, which he was associated for more than 50 at the science, an explicit concern with ETH-Zentrum, CH-8092, Zürich, Switzerland. years. After Ruzicka’s retirement in 1957, molecular shape. Prelog was always e-mail: [email protected]