2nd Nobel Prize in Chemistry: Hermann Emil Fischer

2. Nobel Prize in Chemistry: Hermann Emil Fischer Born on 9 October 1852 in Euskirchen near Bonn in Rhineland, Emil Fischer was one of the most important scientists in the field of organic chemistry. His work on sugar and purine synthesis was honored with the 1902 Nobel Prize in Chemistry.

Education and Academic Training

His father, a successful businessman, wished for him to enter the family timber business, but Emil wanted to study natural sciences, particularly physics. Believing his son lacked the necessary qualities to become a businessman, his father sent Emil Fischer to the University of Bonn in 1871 to study chemistry. Fischer attended lectures by Kekulé, Engelbach and Zincke, as well as August Kundt on physics and Paul Groth on mineralogy. However, in 1872, Emil, who still wished to study physics, was persuaded by his cousin Otto Fischer to join him at the newly established University of Strasbourg, where Professor Rose was working on Bunsen's analytical method. There, Fischer met Adolf von Baeyer, who would greatly influence him and eventually lead him to dedicate his life to chemistry.

A Scientific Career Full of Achievements

Fischer worked on phthalein dyes discovered by Rose and received his doctorate in 1874 from Strasbourg with a thesis on fluorescein and orsin-phthalin. In the same year he was appointed as a lecturer at the University of Strasbourg, and there he discovered phenylhydrazine, the first hydrazine base, and demonstrated its relationship to hydrazobenzene and a sulfonic acid described by Strecker and Römer. The discovery of phenylhydrazine, said to have been accidental, would be connected to much of Fischer's later work. In 1875, von Baeyer was asked to succeed Liebig at the University of Munich, and Fischer went there with him as an assistant in organic chemistry. In 1878, Fischer qualified as a Privatdozent (Lecturer) in Munich and was appointed as Docent in Analytical Chemistry in 1879. In the same year he was offered a position as Professor of Chemistry in Aix-la-Chapelle, but declined it. In 1881 he was appointed Professor of Chemistry at the University of Erlangen. In 1883 he was offered the position of director of the scientific laboratory of Badische Anilin- und Soda-Fabrik. However, Fischer, now financially supported by his father, preferred to continue working in academia. In 1888 he was appointed Professor of Chemistry at the University of Würzburg. He remained there until 1892, when he was asked to succeed A. W. Hofmann in the Chemistry Department at the University of Berlin, where he continued in this position until his death in 1919. Fischer's early discovery of phenylhydrazine and its influence on his subsequent work has already been mentioned. While in Munich, Fischer continued to work on hydrazines and, working with his cousin Otto Fischer, who had followed him to Munich, developed a new theory regarding the structure of dyes derived from triphenylmethane, which they proved correct through experimental work. Emil Fischer worked on caffeine and theobromine, the active principles of tea, coffee and cocoa, and in this field established the structure of a series of compounds and ultimately synthesized them. However, the work on which Fischer's reputation is essentially based was his research on purines and sugars. Conducted between 1882 and 1906, this work demonstrated that various substances then little known, such as adenine, xanthine, caffeine and theophylline in plant material, and uric acid and guanine in animal excrement, all belonged to one homogeneous family, could be derived from one another, and corresponded to different hydroxyl and amino derivatives of the same fundamental system formed by a characteristic bicyclic nitrogen-containing structure containing a urea group. Fischer initially regarded this parent substance as hypothetical and named it purine in 1884, synthesizing it in 1898. Between 1882 and 1896, his laboratory produced numerous artificial derivatives, more or less resembling naturally occurring substances. In 1884, Fischer began his major work on sugars, which transformed knowledge of these compounds and combined the new knowledge obtained into a consistent whole. Even before 1880, the aldehyde formula of glucose had been indicated, but Fischer established this through a series of transformations, including oxidation to aldonic acid and the action of phenylhydrazine, which enabled the formation of phenylhydrazones and osazones. By passing through a common osazone, he established the relationship between glucose, fructose and mannose. Fructose was discovered in 1847 by French chemist Augustin-Pierre Dubrunfaut, but the pioneer investigation of this and all sugars known at that time was conducted by Emil Fischer from 1884 to 1894. Among his other achievements, Fischer demonstrated the relationship between glucose, fructose and mannose and clarified the stereochemistry of these sugars. In 1890 he determined the stereochemical nature and isomerism of sugars through epimerization between gluconic and mannonic acids, and between 1891 and 1894 he skillfully applied the theory of asymmetric carbon atoms published by Van't Hoff and Le Bel in 1874 to establish the stereochemical configuration of all known sugars and completely predicted the possible isomers. He demonstrated the value of his systematic mutual syntheses between different hexoses through isomerization and subsequently between pentoses, hexoses and heptoses through degradation and synthesis reactions. His greatest achievement was in 1890, beginning from glycerol, the synthesis of glucose, fructose and mannose. This monumental work on sugars conducted between 1884 and 1894 was extended by other work, most notably his research on glycosides. Between 1899 and 1908, Fischer made major contributions to knowledge of proteins. He analyzed and sought effective methods for isolating and identifying individual amino acids, discovered a new type of them, cyclic amino acids: proline and hydroxyproline. Furthermore, by obtaining various amino acids in optically active form, he investigated the synthesis of proteins. He succeeded in establishing the type of bond that would link them to one another in chains, namely the peptide bond, and thereby obtained dipeptides and later tripeptides and polypeptides. In 1901, in collaboration with Fourneau, he discovered the synthesis of the dipeptide glycyl-glycine and also published his work on the hydrolysis of casein that year. Amino acids found in nature were prepared in the laboratory and new ones were discovered. The synthesis of oligopeptides resulted in an octadekapeptide possessing many properties of natural proteins. This and subsequent work led to a better understanding of proteins and laid the foundations for later research on them. Fischer also investigated enzymes and chemical substances in lichens he frequently found on holidays in the Black Forest, substances used in leather tanning, and fats in the final years of his life. In 1888, Fischer married Agnes Gerlach, daughter of Professor J. von Gerlach, an Anatomy Professor in Erlangen. Unfortunately, his wife died seven years after their marriage. Fischer lost two of his three sons in the First World War. His other son, Hermann Otto Laurenz Fischer, became Professor of Biochemistry at the University of California, Berkeley. Emil Fischer, who made very significant contributions to science, probably ended his life with his own hand in 1919 at the age of 66, influenced perhaps by his tragic family life and the cancer illness he suffered. References • https://www.pharmakologie.med.fau.de/emil-fischer/ • From Nobel Lectures, Chemistry 1901-1921, Elsevier Publishing Company, Amsterdam, 1966 • https://www.nobelprize.org/prizes/chemistry/1902/fischer/biographical/ • https://www.acs.org/molecule-of-the-week/archive/f/fructose.html