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Hoffman (Hoffmann), Roald

( The American chemist, Nobel Prize in Chemistry, 1981)

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Biography Hoffman (Hoffmann), Roald
genus. July 18, 1937
American chemist Roald Hoffmann (at birth Safran), named after the Norwegian explorer Roald Amundsen was born in g. Zlotszove in Poland (now z. Zolochiv, Ukraine, USSR), the son of an engineer and Hillel Safran schoolteacher Clara Rosen. From the beginning of the Second World War to June 1941. in this area were the Soviet Army. When the German army occupied this area, Safran, Jews by nationality, had been interned in the ghetto and then to a labor camp. In 1943, Mr.. Safranu-senior managed to smuggle her son and his mother from the camp, and the rest of the war they were hiding in the attic of the school near the Ukrainian farm. Father X. remained in the camp and, like most prisoners, was destroyed by the Nazis. H. and his mother managed to stay alive and were released by the Soviet Army in June 1944. Later they moved to Krakow, where the boy was able to attend school and where his mother was married to Paul Hoffman.
During the next three years, Hoffman lived in a displaced persons camp in Austria and Germany. In 1949, Mr.. they were able to emigrate to the United States of America, which settled in New York. H. learned English, his sixth language, attending public school in Brooklyn, and then entered Stuivesantskuyu secondary school, specialized in the study of natural science subjects. He began his higher education in medicine at Columbia University in 1955. and three years later received a bachelor's degree, then at Harvard University, majored in chemistry.
In 1959, Mr.. at Uppsala University in Sweden X. listened to the summer course on quantum chemistry. At this time, he met with Eva Beresson, in 1960. They married and went to Harvard. Shortly thereafter, the couple spent a year in the Soviet Union, where X. studied in Moscow State University 'sharing'.
Returning to Harvard, X. begin joint research with William H. Lipscomb, using computer technology to calculate the energy barriers in organic molecules. He used the Hц+ckel rule (which determines the number of electrons in the electron cloud of the molecule) to calculate the electronic structure of boron hydrides and polyhedral molecules. After receiving his doctorate in 1962. H. worked for three years at Harvard, with a scholarship to perform research. Influenced EJ. Corey and R.B. Woodward, he switched from theoretical chemistry applied to organic chemistry.
. Quantum theory, developed mainly in the 20-ies of Louis de Broglie, Erwin Schrodinger and Werner Heisenberg, is a mathematical description of the behavior of particles at the atomic and subatomic level
. Quantum mechanics - the application of this theory to the motion of particles. In 1965, trying to find the explanation somewhat unexpected reaction, discovered by Woodward in the synthesis of vitamin B12, Woodward and X. discovered the laws that are based on quantum mechanics and allow to predict whether productive reaction to certain combinations of chemical reagents.
. The basis of the laws of the Woodward - Hoffman founded a well-known the 70-ies of the last century, the idea that the system tends to adopt a configuration in which its energy would be minimal
. If the compounds formed have an energy less than the initial reagents, the reaction proceeds at the given atmospheric conditions (pressure and temperature). If the reaction product is at a higher energy level than the sum of the individual parent compounds, such a reaction is not prozoydet.
. Chemical bonding between atoms formed by superposition of the electron orbits, which occurs when the orbital (area of highest probability of finding electrons) of the reactants are symmetrical
. In other words, they should be in the same space and in the same phase. Laws of the Woodward - Hoffman provide an opportunity for Mathematical prediction, . whether a certain chemical reaction is supposed to maintain symmetry and, accordingly, whether to form a product with a stronger bond and greater stability, . than the initial reagents.,
. Woodward and X
. analyze these effects of orbital symmetry for reactions in which several bonds broken or formed simultaneously rather than sequentially for the processes taking place with the formation of intermediate compounds. Laws of the Woodward - Hoffman received considerable attention as the most outstanding theoretical achievements since the Second World War. Because of the simplicity of the language and the lack of requirements of complex computer processing, they are widely used in practical medicine and industry. Their relative simplicity is consistent with H. conviction that the ability to reliably make predictions without laboratory computing is the basis for understanding. 'If you refer to your computer, then you do not understand the law' - he says. Woodward and X. described their discovery in 1970. the book 'Conservation of orbital symmetry' ( 'The Conservation of Orbital Symmetry').
At the end of fellowships X. in 1965. passes in at Cornell University as Adjunct Professor of Chemistry (1965 ... 1968), and then becomes full (real) Professor. In 1974. He was awarded the title of professor of physical sciences.
In 1981. H. with Kenichi Fukui was awarded the Nobel Prize in Chemistry 'for the development of the theory of chemical reactions created by them independently of each other'. Although Fukui has developed his ideas before H., his deep matematizirovannye articles published in Japanese journals, read only a small circle of Western chemists. 'Concept of frontier orbitals and the conservation of orbital symmetry expanded the borders of understanding the interaction of molecules when they collide', - said Inga Fischer-Hyalmars, a member of the Royal Swedish Academy of Sciences, in his speech at the presentation of the winners. 'As a result of your theoretical work, new, great value opportunities for planning chemical experiments'.
After receiving the Nobel Prize X. interested in the relationship of structure and reactivity of inorganic and organometallic compounds, from small diatomic complexes to clusters comprising a few atoms of transition metals. Using a molecule consisting of a metal-ligand fragments, X. also investigated the formation of clusters and the geometry of the olefin and polyene-metallokarbonilnyh complexes. The predicted structure of new types of sandwich and porphyrin 'sandwiches' were synthesized by other researchers. He and his colleagues also are studying solid-state structure.
Other interests X. were associated with understanding the relationship between science and art, and similar processes in these two areas. Hoffman, who have a son and daughter, live in Ithaca (New York). H. received U.S. citizenship.
In addition to the Nobel Prize, X. won the Society of Chemistry Highly Pure Compounds (1969), lecturing award Garrison E. Hove (1970), Award of Arthur K. Cope (with Woodward) in 1973, . Award Pauling (1974), . Nichols Medal (1981) and a prize for outstanding achievements in the development of inorganic chemistry (1982), . with all the prizes were awarded by the American Chemical Society, . as well as the prize of the International Academy of Quantum Molecular Science, (1971),
. He is a member of the U.S. National Academy of Sciences, the American Association of Basic Sciences, International Academy of Quantum Molecular Science, and the American Physical Society. He holds honorary degrees of the Royal Institute of Technology in Sweden and at Yale University.


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AMUNDSEN Roald (Roald)
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Hoffman (Hoffmann), Roald, photo, biography
Hoffman (Hoffmann), Roald, photo, biography Hoffman (Hoffmann), Roald  The American chemist, Nobel Prize in Chemistry, 1981, photo, biography
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