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Hassel Odd

( Chemist, Nobel Prize in Chemistry, 1969)

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Biography Hassel Odd
Hassel, Odd (Hassel, Odd), (1897-1981). Nobel Prize in Chemistry, 1969 (jointly with D. Burton).

Born May 17, 1897 in Christiania (now Oslo, Norway) in the family gynecologist Ernst Hassel) and Mathilde Klaveness. His father died when he was 8 years old. Odd, his sister and three brothers, brought her mother, a man of great culture. After school in Oslo (then he fell in love with chemistry) Odd studied chemistry, mathematics and physics at the University of Oslo, which he graduated in 1920.

After a year's trip to France (where he attended the lectures of physicist Paul Langevin) and Italy Xassel continued his studies at Munich University, and then transferred to Berlin University. Prior to that he managed to work in Berlin at the Institute of Physical Chemistry and Electrochemistry, Kaiser Wilhelm, which has mastered a new method of X-ray analysis. The recommendation of the Director of the Institute of F. Haber (Nobel Laureate, 1918) received a Rockefeller scholarship Hassel, while still an intern at Berlin University. Hassel investigated the structure of graphite, bismuth, molybdenum disulfide and other inorganic substances. Dissertation exams he took such luminaries, . as Max von Laue (Max von Laue, . 1879-1960, . Nobel laureate, . 19140) (physics), . F. Haber (chemical technology) and a prominent specialist in the field of kinetics of Max Bodenstein (Max Bodenstein, . 1871-1942) (physical chemistry),
.

After receiving in 1924 the University of Berlin doctoral Xassel in 1925 became a teacher of the University of Oslo, and the next year - an assistant professor of physical chemistry and electrochemistry. He built his own device for X-ray analysis, and with it engaged in an analysis of the structure of inorganic compounds. It was not only simple inorganic salts, but also various complex compounds of cobalt, indium, zirconium, iron, etc.. In 1933 he wrote a monograph Crystal. Book translated from German into English and Russian languages.

Then it is time to study the structure of organic substances. Then he added to the x-ray diffraction measurement of the dipole moments. Began with the simple structure of substances - derivatives with nitro, cyano, amino and other groups. In 1930, he became interested in the molecule of cyclohexane. This compound is a cycle consisting of 6 carbon atoms, which are attached 12 atoms of hydrogen. Six-membered cyclic structure is typical for structures of many important natural molecules, including steroids and most of the carbohydrates. When Xassel X-ray diffraction data confirmed earlier studies, . indicating, . that the six-membered carbon ring can take spatial forms, . commonly referred to as configurations of 'bath' and 'chair' (the molecule is shaped like a bathtub and chair),
.

In 1934 Xassel moved to set up while the Department of Physical Chemistry at the University of Oslo and became its leader. To obtain more meaningful results Hassel improved method of gas electron diffraction, developed earlier in Germany in 1930.

In 1938, realizing the limited capacity of X-ray analysis, Xassel began to apply new techniques such as electron diffraction. In 1940, he showed that a molecule of cyclohexane - not flat. Continuing in the early 1940's, studies with cyclohexane, he was able to compile some of its conclusions. Discovered that cyclohexane molecules pass from the form 'bath' in the 'chair' and back at speeds of up to one million times per second. Such dynamic spatial forms were called conformations, and the questions of the spatial structure of molecules and related properties were called conformational analysis. Hassell has proved that for the six-membered carbon rings of the two possible conformations of the form of 'chair' is energetically more favorable.

Hassel spread their ideas on the presentation of the spatial structure of condensed cyclohexane rings (typical for steroids), as well as carbohydrates, are in cyclic form.

In 1943, he found that the substituents in the cyclohexane ring may occupy different spatial positions, which he called the axial and equatorial. However, with the beginning of the Second World War, he refused to be published in German scientific journals, and his work remained little known.

During the occupation of Norway, Germany, University of Oslo was closed and Xassel together with other patriots, was arrested by the Nazis and was in a concentration camp during all this time.

After the war, he summarized his observations in three review articles, written in 1947, 1950 and 1953 and continued work on the molecular configuration. In the 1950's began to study the physical structure of the charge-transfer. These compounds are formed by the interaction of molecules - electron donors, such as esters, with molecules - electron acceptors, such as some chlorine and fluorine. He eventually brought the laws that explain the geometry of certain types of compounds with charge transfer.

Although Xassel resigned from the University of Oslo in 1964, he was still several years active in continuing scientific activities.

Xassel and D. Barton, in 1969 shared the Nobel Prize 'for his contribution to the development of the concept of conformation and its application in chemistry'. Arne Fredga (Arne Fredga), a member of the Royal Swedish Academy of Sciences, in his speech at the presentation of the winners said: 'clever piece of work Xasselya with six-membered rings served as the foundation for a dynamic stereochemistry'.

Which appeared in 1950, a brief article in the journal Barton 'Experientia', called "The conformation of the steroid nucleus, compared meaningfully with the classical stereochemical studies Ya.Vant Hoff (Nobel Prize in Chemistry, 1901). Here's how Burton himself has determined that such a conformational analysis. This is the 'preferred form of the correlation (or conformation) of the molecule with its physical and chemical properties'. Conformation of the same - 'the way the molecules interact with other molecules'

. Ideas of conformational analysis are basic principles of modern organic chemistry and biochemistry, . explain the properties of the main classes of biomolecules, . mechanism of action of physiologically active substances - drugs, . toxic agents, etc., . binding of biologically active molecules receptors, . enzyme-substrate interactions,
. Not surprisingly, the emergence of the winners of the first works in this area (there were many) gave rise to an avalanche of publications in the field of conformational analysis. He immediately took a firm place in the arsenal of chemists.

Vicious man Xassel rarely attended international scientific conferences and was not personally acquainted with most colleagues on the scientific work.

Died May 15, 1981 in Oslo, before reaching two days before his 84 birthday.


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