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The Nobel Prize in Chemistry
Dátum pridania: 21.08.2007 Oznámkuj: 12345
Autor referátu: holdenko
Jazyk: Angličtina Počet slov: 10 788
Referát vhodný pre: Gymnázium Počet A4: 37.9
Priemerná známka: 2.95 Rýchle čítanie: 63m 10s
Pomalé čítanie: 94m 45s

The preparation of a new form of carbon compounds was also recognized by the Nobel Prize for Chemistry in 1996 to Robert F. Curl, Jr., of Rice University, Sir Harold W. Kroto of the University of Sussex and Richard E. Smalley of Rice University. These investigators had in 1985 discovered compounds, called fullerenes, in which 60 or 70 carbon atoms are bound together in clusters in the form of a ball. The designation fullerenes is taken from the name of an American architect, R. Buckminster Fuller, who had designed a dome having the form of a football for the 1967 Montreal World Exhibition.

3.8 Preparative Organic Chemistry
One of the chief goals of the organic chemist is to be able to synthesize increasingly complex compounds of carbon in combination with various other elements, such as hydrogen, oxygen, nitrogen, sulfur and phosphorus. The first Nobel Prize for Chemistry recognizing pioneering work in preparative organic chemistry was that to Victor Grignard from Nancy and Paul Sabatier from Toulouse in 1912. Grignard had discovered that organic halides can form compounds with magnesium. These compounds, now generally called Grignard reagents, are very reactive, and they are consequently widely used for synthetic purposes. Sabatier was given the prize for developing a method to hydrogenate organic compounds in the presence of metallic catalysts. With his method oils can be converted to saturated fats, and it is, for example, used for margarine production and other industrial processes.

The prize in 1950 was presented to Otto Diels from Kiel and Kurt Alder from Cologne "for their discovery and development of the diene synthesis", also called the Diels-Alder reaction. In this reaction, which was developed already in 1928, organic compounds containing two double bonds ("dienes") can effect the syntheses of many cyclic organic substances. During the decades following the original work several industrial applications of the Diels-Alder reaction have been found, for example, in the production of plastics, which may explain the lateness of the prize.

The German organic chemist Hans Fischer from Munich had already done significant work on the structure of hemin, the organic pigment in hemoglobin, when he synthesized it from simpler organic molecules in 1928. He also contributed much to the elucidation of the structure of chlorophyll, and for these important achievements he was awarded the Nobel Prize for Chemistry in 1930 (cf. Section 3.5). He finished his determination of the structure of chlorophyll in 1935, and by the time of his death he had almost completed its synthesis as well.

Robert Burns Woodward from Harvard is rightly considered the founder of the most advanced, modern art of organic synthesis. He designed methods for the total synthesis of a large number of complicated natural products, for example, cholesterol, chlorophyll and vitamin B12. He received the Nobel Prize for Chemistry in 1965, and he would probably have received a second chemistry prize in 1981 for his part in the formulation of the Woodward-Hoffmann rules (see Section 3.4), had it not been for his early death. Work in synthetic organic chemistry was also recognized in 1979 with the prize to Herbert C. Brown of Purdue University and Georg Wittig from Heidelberg, who had developed the use of boron- and phosphorus-containing compounds, respectively, into important reagents in organic synthesis. Another master in chemical synthesis is Elias James Corey from Harvard, who received the prize in 1990. He had made a brilliant analysis of the theory of organic synthesis, which permitted him to synthesize biologically active compounds of a complexity earlier considered impossible.

The Nobel Prize for Chemistry in 1984 was given to Robert Bruce Merrifield of Rockefeller University "for his development of methodology for chemical synthesis on a solid matrix". Specifically, Merrifield applied this ingenious idea to the synthesis of large peptides and small proteins, for example, ribonuclease (cf. Section 3.12), but the principle has later also been applied to nucleic acid chemistry. In earlier methods each intermediate in the synthesis had to be isolated, which resulted in a drastic drop in yield in syntheses involving a large number of consecutive steps. In Merrifield's method these isolation steps are replaced by a simple washing procedure, which removes by-products as well as remaining starting materials, and in this way substantial losses are avoided.

3.9 Chemistry of Natural Product
The synthesis of complex organic molecules must be based on detailed knowledge of their structure. Early work on plant pigments was carried out by Richard Willstätter, a student of Adolf von Baeyer from Munich (see Section 2). Willstätter showed a structural relatedness between chlorophyll and hemin, and he demonstrated that chlorophyll contains magnesium as an integral component. He also carried out pioneering investigations on other plant pigments, such as the carotenoids, and he was awarded the Nobel Prize for Chemistry in 1915 for these achievements. Willstätter's work laid the ground for the synthetic accomplishments of Hans Fischer (see Section 3.8). In addition, Willstätter contributed to the understanding of enzyme reactions.
The prizes for 1927 and 1928 were both presented to Heinrich Otto Wieland from Munich and Adolf Windaus from Göttingen, respectively, at the Nobel ceremony in 1928. These two chemists had done closely related work on the structure of steroids. The award to Wieland was primarily for his investigations of bile acids, whereas Windaus was recognized mainly for his work on cholesterol and his demonstration of the steroid nature of vitamin D. Wieland had already in 1912, before his prize-winning work, formulated a theory for biological oxidation, according to which removal of hydrogen (dehydrogenation) rather than reaction with oxygen is the dominating process.
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Zdroje: Westgren, A., Nobel – The Man and His Prizes, ed. Odelberg, W. (Elsevier, New York, 1972), pp. 279-385., Kormos Barkan, D., Walther Nernst and the Transition in Modern Physical Science, (Cambridge University Press, 1999)., Rife, P., Lise Meitner and the Dawn of the Nuclear Age, (Birkhäuser, 1999).
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