Rainer Ludwig Claisen

Rainer Ludwig Claisen ( born January 14, 1851 in Cologne, † January 5, 1930 at Godesberg, today Bonn ) was a German chemist.

Life and work

Ludwig's father was a respected counselor and notary in Cologne. With his brothers, he attended a altsprachliches, Catholic high school in Cologne, which he left in 1869 with the Abitur. He studied from 1869 to 1871 chemistry at the University of Bonn in Theophil Engelbach, between 1871 to 1873 with Hans Hübner, Friedrich Wöhler and Bernhard Tollens in Göttingen chemistry. After the PhD. in 1875 with the work contributions to the knowledge of the Mesityloxyds and Phorons in Bonn in August Kekulé he was initially his assistant.

In 1878 he completed his habilitation there and was subsequently adopted as a lecturer. From 1881 Claisen dealt with the reaction of malonic esters with ketones. Later he studied with his students the implementation of acetoacetic ester with ketones and aldehydes.

For some years he went to the Owens College, Manchester, and then as an employee of Adolf von Baeyer in Munich. In 1890 he followed a call to the RWTH Aachen, where he became professor of chemistry for the main areas of work: was appointed Synthetic Organic Chemistry and tautomerism phenomena ( Claisen allyl - oxygen, carbon - allylic rearrangement ). In 1897 moved to Claisen University of Kiel, where he became professor emeritus in 1902 for health reasons initially, but in 1904, for some time to the University of Berlin moved to there complete its begun research on the effect of sodium amide in condensations. Then he moved permanently back into the Rhineland, where he still ran a private laboratory.

In 1877 his work was published studies on organic Saurecyanide. In this work, the easy convertibility of benzoyl cyanide was shown to benzoylformic and acetyl cyanide to pyruvic acid. In his habilitation thesis was also a representation of isatin, a precursor of indigo, pointed out.

In 1881 he discovered the now named after him Claisen condensation of carboxylic acid esters and the Claisen Tiščenko reaction for the preparation of carboxylic acid esters from aldehydes. Some he developed laboratory equipment such as the Claisen head, Claisen flask and the Claisen coolers are named after him. Even in retirement, he discovered named after him also Claisen rearrangement of Phenylallylethern in o- allyl phenols.

Ludwig Claisen was a member of the Bavarian Academy of Sciences and an honorary member of the Association of German Chemists and has been for his services, among others, Dr. Ing Eh RWTH Aachen appointed. In 1881 he was elected a member of the Leopoldina.