Knorr, Ludwig

Keller, Hans, 102 Knietsch, Rudolf, 75, 86, 91 Knorr, Ludwig, 67 Konig, A., 74, 77 Koppel, Leopold, 226, 231 Kranz, Julius, 81 Krassa, Paul, 78, 81 Krauch, Carl, 98, 105, 225 Kuhlmann, Charles F., 99... 

Knorr, L. Ber Dtsch. Chem. Ges. 1883, 16, 2597. Ludwig Knorr (1859—1921) was bom near Munich, Germany. After studying under Volhard, Emil Fischer, and Bunsen, he was appointed professor of chemistry at Jena. Knorr made tremendous contributions in the synthesis of heterocycles in addition to discovering the important pyrazolone drug, pyrine. 

Wolff, L. Justus Liebigs Ann. Chem. 1912, 394, 25. Johann Ludwig Wolff (1857-1919) obtained his doctorate in 1882 under Fittig at Strasbourg, where he later became an instructor. In 1891, Wolff joined the faculty of Jena, where he collaborated with Knorr for 27 years. 

The well-known German chemist, Ludwig Knorr, reported the preparation of the first pyrazolinone in 1883.805 This compound was 3-methyl-l-phenyl-2-pyrazolin-5-one prepared by the reaction of ethyl acetoacetate with phenylhydrazine. In the first publication no structure was proposed, but in a later publication806 structure (VI) was suggested. 

The first synthetic heterocyclic pharmaceutical seems to be antipyrine. Antipyrine is a pyrazole analgesic and an antipyretic, like aspirin. Ludwig Knorr used Emil Fischer s discoveiy of phenylhy-drazine to synthesize antipyrine, and in 1883, Knorr was granted a patent on the synthesis. In 1885, one year after market introduction, almost 6 metric tons were sold, and in 1899, sales had grown to almost 800 metric tons. More recently, antipyrine has been used in a solution with benzocaine to relieve ear pain and swelling caused by middle ear infections. Knorr s synthesis is shown in Scheme 8.1. Details of the Knorr synthesis are discussed in Chapter 4. 

Fischer was a very private person. While he enjoyed company in his younger years, he cultivated real friendship with only very few people, with his cousin Otto, with Ludwig Knorr, his assistant in Erlangen for many years, or with W. Koenigs and later in life with C. Duisberg, both former fellow students. Curtius was similarly an introvert, his personality, as characterized by Heinrich Wieland in an obituary, always clouded under the veil of a certain reservation . This might contribute to our understanding of the distance Fischer and Curtius kept from each other. 

Ludwig Knorr, Robert Pschorr, Heinrich Otto 5,53 Bottle with heroin in Wieland and also Robinson himself, finally powder form. 

Ludwig Knorr (Munich, 2 December 1859-Jena, 5 June 1921), a pupil of Baeyer, Bunsen, and Emil Fischer, was associate professor in Wurzburg (1888) and professor in Jena (1889). much work on pyrazolones... 

History Ludwig Knorr (1883) has given the name pyrazole to this class of compounds. The reduced forms of p3rrazoles are pyrazoline and pyrazolidine. The substituted derivatives of pyrazole has been used in medicines and in other technical applications. 

Fischer s phenylhydrazine was an integral link in the synthesis of antipyrine, a successful febrifuge, carried out by his own student and friend, Ludwig Knorr (1859-1921)... 

A variation of this reaction that involves a 1,4-diketone rather than a keto-ester is very useful. If a simple amine such as ethylamine (EtNHa) reacts with 2,5-hexanedione (115), the product is pyrrole 116 in what is called the Paal-Knorr synthesis, after Carl Paal (Austria 1860-1935) and Ludwig Knorr. 

Ludwig Wolff (1857-1919) was bom in Neustadt in the Palatinate and was educated at the University of Wtirzburg and Munich Polytechnic. In 1891, he became Professor of Analytical Chemistry at Jena, where he worked with Ludwig Knorr. His name is associated with the Wolff-Kishner reaction (1911) and the Wolff rearrangement (1912). 

Professor Karl Paal (1860-1935), University of Erlangen, Germany Professor Ludwig Knorr (1859-1921), University of Jena, Germany. 

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