JOURNAL OF CHEMICAL EDUCATION
KARL ZIEGLER RALPH E. OESPER University of Cincinnati, Cincinnati, Ohio
CHEMICALRESEARCH is rapidly being revitalized in war-torn Germany. There is shortage of chemicals, glassware, and equipment; recent foreign books and periodica.ls are seldom available; heat, , water and current, etc., are often interrupted, but the old-time energetic spirit is bravely meeting and overcoming these handicaps. The German chemical journals are beginning t o appear again when the paper supply permits, and new books are likewise coming on the market. One of the leaders in this postwar revival is the wellknown organic chemist, Karl Ziegler. (See frontispiece). Born November 26, 1898, a t HeLsa near Cassel, he studied a t Marhurg under K. von Auwers. After receiving the doctorate in 1920 he stayed on as assistant and privat dozent. In 1925 he transferred to the University of Frankfort a. M. and then (1926) to the University of Heidelberg, where he headed the organic section. In 1936 Ziegler visited a number of American universities and was guest lecturer a t Chicago for several weeks. On his return to Germany he was called to head the chemistry department a t Halle. He filled this post with such distinction that in 1943 he was named to suc-' ceed Franz Fischer as director of the world-famous Kaiser Wilhelm Institut fiir Kohlenforschung a t Miilheim (Ruhr). Dr. Ziegler opened his scientific career with the synthesis of some new free radicals. The early conviction that purely preparative organic studies would never result in definite theoretical conclusions induced him to enter on a coniprehensive series of studies of the rea.ction
kinetics and energetics of labile polysubstituted ethanes (1929, 1930, 1933, 1942). The work with free radicals led h i to the organo compounds of the alkali metals. He discovered that ether scission opened a new method of preparing sodium and potassium alkyls; later (1930) he directly synthesized lithium alkyls and aryls from metallic lithium and halogenated hydrocarbons. This important discovery made the lithium compounds as readily available as the familiar Grignard reagents. Because of their greater activity, impressive developments in organic synthesis arose from the Ziegler organo-metallic compounds. He himself found new reactions in the heterocyclic field (1930) and he observed the addition of alkali alkyls to -C=G-double bonds (1927). This latter observation initiated comprehensive studies of certain polymerization reactions, especially the formation of butadiene-sodium rubber (1929, 1934,1939). The alkali alkyls also opened a way to solving the problem of the synthesis of large ring compound from long aliphatic chains. The consequent combination of the "dilution principle" with the new ring closure reactions made possible the synthesis, in good yields, of many polymethylene ketones. An outstanding instance was the preparation of muscone, the odoriferous principle of animal musk. Ziegler, together with A. Liittringhaus, and then the latter alone, used the new methods for preparing unusual (m-, p-, etc.) rings. Cantharidine, the actiye principle of Spanish fly, was synthesized by Ziegler in 1942. An outgrowth of this
SEPTEMBER, 1948
work was the preparation by him and his student, G. Schenck, of the natural peroxide ascaridole from a-terpenes. Ziegler also found that N-bromo-succinimide is an excellent reagent for introducing a bromine atom into the ally1 position of unsaturated compounds. This reagent has now found wide favor in preparative work. Most of Ziegler's papers have appeared in the An-
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nalen der Chemie. He is the author of various chapters in the Freudenberg "Stereochemie" (1933) and the "Handbuch der Katalyse" (1943). He is a member of the Academies a t Halle and Munich. In 1938 he was awarded its Liebig Medal by the Verein Deutscher Chemiker, and since 1946 has been the president of . the Gesellschaft Deutscher Chemiker.
