Rainer Ludwig Claisen
Rainer Ludwig Claisen in 1897
Born(1851-01-14)14 January 1851
Cologne
Died5 January 1930(1930-01-05) (aged 78)
Godesberg am Rhein
NationalityGerman
Known forwork with condensations of carbonyls and sigmatropic rearrangements
Scientific career
Fieldschemistry

Rainer Ludwig Claisen (German pronunciation: [ˈʁaɪnɐ ˈklaɪzn̩]; 14 January 1851 – 5 January 1930) was a German chemist best known for his work with condensations of carbonyls and sigmatropic rearrangements. He was born in Cologne as the son of a jurist and studied chemistry at the university of Bonn (1869), where he became a member of K.St.V. Arminia. He served in the army as a nurse in 1870–1871 and continued his studies at Göttingen University. He returned to the University of Bonn in 1872 and started his academic career at the same university in 1874. He died in 1930 in Godesberg am Rhein (near Bonn).

Career

1874 Promotion at the University of Bonn; position at Kekulé's laboratory
1878 Habilitation as Privatdozent at the University of Bonn
1882 Worked with Henry Roscoe and Carl Schorlemmer at Owens College, Manchester (until 1885)
1886 Worked at the laboratory of von Baeyer (University of Munich)
1887 Habilitation as Privatdozent at the University of Munich
1890 Position as Professor ordinarius of organic chemistry at TH Aachen
1897 Position as Professor ordinarius of chemistry at the University of Kiel
1904 Honorarprofessor at the University of Berlin, collaboration with Emil Fischer
1907 Emeritus; starts his own private laboratory in Godesberg am Rhein

Scientific contributions

See also

References

  1. ^ Lassar-Cohn (1906). Arbeitsmethoden für organisch-chemische Laboratorien [Methods of working for organic chemistry laboratories] (in German) (4th ed.). Hamburg and Leipzig, Germany: Leopold Voss. p. 67.
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Notes

  1. ^ A description and depiction of Claisen's flask appeared in: Claisen, L. (1893). "Beiträge zur Kenntniss der 1,3-Diketone" [Contributions to [our] knowledge of 1,3-diketones]. Annalen der Chemie (in German). 277 (1–2): 162–206. doi:10.1002/jlac.18932770108. Translation of footnote (31) on pages 177–178, which describes and depicts Claisen's flask: 31) During vacuum distillations that were often performed during this and other work, I used advantageously fractionation flasks of a form like those seen in the figures below. The neck of the flask is, as in the case of the distillation apparatus that was devised by Kahlbaum, in two parts; one piece serves for the installation of the capillary tube, [and] the attachment on the side, for the insertion of the thermometer; the upper openings are of such width that a piece of rubber tubing can conveniently be put on [them], and on the other side, the capillary tube and the thermometer can still be easily inserted. One thus avoided the troubles that the use of two-holed rubber stoppers bring with them — the frequent breaking off of the capillary threads and the crushing of the thermometer. Furthermore, these fractionation flasks have still other advantages, which caused me to prefer them to the apparatus by which Anschütz avoided, in a clever way, the two-hole stopper. A surge of the liquid up into the condenser during fitful boiling is less possible here than in the case of a simple one-necked flask; it can be completely avoided if one pours into the (in this case not constricted) side tube (Figure II) a few coarse pieces of glass, which break the thrust of the upwards rushing liquid. One can fill — completely or partially — the space above the glass pieces with glass beads (naturally only in the case of liquids of not too high boiling point), and thus combine the advantages of Hempel's column with vacuum distillation. In the latter way, I have been able to achieve many faster separations and many sharper boiling points than by the usual procedure. However, even without the glass pieces and beads, the differences, highlighted by Anschütz, of heating over an open flame and of distillation using an oil bath don't assert themselves, in large measure, as [they do] in the case of the simple one-necked flask. Flasks of the type mentioned are custom made by the glass blowing firm of C. Heinz & Co. in Aachen. (For literature on this subject, see: Kahlbaum, Boiling Temperature and Pressure, Leipzig, 1885; Anschütz, Distillation Under Reduced Pressure, Bonn 1887; Hantzsch, these Annals 249: 57.) The use of a short Hempel's column during vacuum distillation has also been recommended by Michael (Journal für praktische Chemie, 47: 197).
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