Background
Claisen was born on January 14, 1851, in Cologne, Germany, the son of Heinrich Wilhelm Claisen, a notary, and of the former Emilia Theresa Berghaus. He had two brothers and a sister.
Regina-Pacis-Weg 3, 53113 Bonn, Germany
Claisen enrolled in the University of Bonn in 1869 and received the doctorate there in 1874.
Claisen was born on January 14, 1851, in Cologne, Germany, the son of Heinrich Wilhelm Claisen, a notary, and of the former Emilia Theresa Berghaus. He had two brothers and a sister.
After graduating in 1869 from the Gymnasium of the Apostles Church in Cologne, Claisen enrolled in the University of Bonn, where he studied chemistry under Kekulé and physics under Clausius.
His studies were interrupted by the Franco-Prussian War, and Claisen enlisted as a medical corpsman. At Gottingen he attended Tollens’ lectures on organic chemistry and worked in Wohler’s laboratory. He returned to Bonn in 1872 and received the doctorate there in 1874.
Claisen taught at Bonn from 1875 to 1882 and at Owens College in Manchester, England, from 1882 to 1885. During the next four years he worked in Baeyer’s laboratory at Munich, leaving to teach at the Aachen Technische Hochschule from 1890 to 1897. He was associate professor at the University of Kiel from 1897 to 1904 and worked in Emil Fischer’s laboratory in Berlin from 1904 to 1907.
In 1907 Claisen established his own laboratory at Godesberg, continuing work in organic synthesis until 1926. Claisen’s early interest in condensation reactions led him to develop the so-called Claisen condensation for synthesizing keto esters and 1,3-diketones. He used sodium hydroxide, hydrogen chloride, sodium ethoxide, and sodamide as condensing agents and found that nitriles, as well as carbonyls, may be condensed.
Claisen contributed greatly to the understanding of taulomerism when, in 1893, he reported the isolation of dibenzoyl acetone in two solid modifications, identifying the acidic form as enol and the neutral as keto and extending these terms to apply to all tautomers. In 1912 Claisen began work on the rearrangement of allylaryl ethers into phenols. The mechanism of this rearrangement was the subject of the last (1926) of his 125 published papers. Eulogizing Claisen, Richard Anschutz said that he was endowed with first-rate talent and that his discoveries placed him among the most renowned researchers in organic chemistry.
German Academy of Sciences Leopoldina. Bavarian Academy of Sciences and Humanities.