20th-century German chemists

Ferdinand Karl Franz Schaum (14 July 1870, Frankfurt am Main – 30 January 1947, Gießen) was a German chemist who specialized in the field of photochemistry.
He studied mathematics and sciences at the Universities of Basel, Berlin, Leipzig and Marburg, earning his doctorate at the latter institution in 1893. Afterwards, he served as an assistant to Theodor Zincke at Marburg and to Wilhelm Ostwald in Leipzig. In 1897 he obtained his habilitation at Marburg with a thesis on types of isometry.In 1904 he became an associate professor of physical chemistry at the University of Marburg, where he was an important influence towards the career of chemist Max Volmer. In 1908 he relocated to the University of Leipzig as an associate professor of photochemistry and scientific photography. From 1914 to 1935 he worked as a full professor of physical chemistry at the University of Giessen.Schaum was a member of the Gesellschaft zur Beförderung der gesamten Naturwissenschaften Marburg.

Otto Ruff (12 December 1871 – 17 September 1939) was a German chemist.

Georg Lockemann (17 October 1871, in Hollenstedt – 4 December 1959, in Hollenstedt) was a German chemist.

Friedrich Hermann Leuchs (8 August 1879 – 2 May 1945) was a German chemist.

Heinrich Hubert Maria Josef Houben (27 October 1875, in Waldfeucht (Rheinland) Germany – 28 June 1940, in Tübingen) was a German chemist. He made achievements within ketone synthesis, terpenes, and camphor studies. After being wounded several times on the front lines in World War I, Houben was made head of the war laboratory. He improved the Hoesch reaction which is now normally called Houben-Hoesch reaction. Houben organized and made a major rework of the book Methods of Organic Chemistry which is now referred to as Houben-Weyl Methods of Organic Chemistry.

Karl Johann Freudenberg (29 January 1886 Weinheim, Baden – 3 April 1983 Weinheim) was a German chemist who did early seminal work on the absolute configurations to carbohydrates, terpenes, and steroids, and on the structure of cellulose (first correct formula published, 1928) and other polysaccharides, and on the nature, structure, and biosynthesis of lignin. The Research Institute for the Chemistry of Wood and Polysaccharides at the University of Heidelberg was created for him in the mid to late 1930s, and he led this until 1969.

Alexander Ellinger (17 April 1870 in Frankfurt am Main – 26 July 1923 in Frankfurt am Main) was a German chemist and pharmacologist.
From 1887 he studied chemistry at the University of Berlin under August Wilhelm von Hofmann and at the University of Bonn as a pupil of August Kekulé. Afterwards, he studied medicine at the University of Munich, followed by work as an assistant in the institute of pharmacology at the University of Strasbourg. In 1897 he became an assistant to Max Jaffé in the laboratory of medicinal chemistry and experimental pharmacology at the University of Königsberg. In 1914 he was appointed professor of pharmacology at the newly established University of Frankfurt.He is remembered for his extensive biochemical research of several amino acids, especially tryptophan. In 1904 he isolated kynurenic acid from the urine of dogs that had been fed tryptophan. His other work included studies on the water exchange between body tissues and blood, on the formation on lymph, and with chemist Karl Spiro, he conducted investigations of blood coagulation.

Paul Pfeiffer (21 April 1875 – 4 March 1951) was an influential German chemist. He received his Ph.D. at the University of Zurich, studying under Alfred Werner, the "father of coordination chemistry". His thesis, submitted in 1898, dealt with adducts of tin halides.
Pfeiffer was considered Werner's most successful student and became Werner's assistant until, due to a dispute with his mentor, he left first for Rostock, then Karlsruhe, and finally Bonn. At Bonn, where he had studied as an undergraduate, he occupied Kekulé's chair.
Pfeiffer's work spanned many themes. The Pfeiffer effect, which involves interactions between chiral solutes, is named after his discoveries. His group first made the salen ligands, which gave the first artificial oxygen carriers. He recognized that crystals, e.g. of zinc sulfide, are large molecules.

Friedrich Carl Duisberg (29 September 1861 – 19 March 1935) was a German chemist and industrialist.