Summary

Hermann Emil Fischer († July 15, 1919 in Wannsee) was a German chemist and professor of organic chemistry. His scientific work includes the synthesis of phenylhydrazine, which he used to synthesize indole and to elucidate the stereochemistry of sugar molecules. He also synthesized various stereoisomers of sugars. The Fischer projection, which he introduced, is a method for unambiguously mapping the spatial structure of chiral sugar compounds. He synthesized the first barbiturate, diethyl barbituric acid (Veronal), in 1902.

Emil Fischer also researched the chemical structure of uric acid, xanthines, caffeine and other natural substances, and proved that these are derived from a nitrogenous base with a bicyclic structure, which he called purine. For his work on the chemistry of sugars and purines, the Nobel Committee awarded him the Nobel Prize in Chemistry in 1902.

As a further class of substances, he investigated amino acids and proteins and synthesized smaller peptides. His work on enzymes and the metabolism of sugar stereoisomers by yeasts led to Fischer's formulation of the lock-and-key principle between enzyme and substrate. Finally, he explored the substance class of lipids and depsides. His research forms the basis of organic chemistry and biochemistry.

As successor to August Wilhelm von Hofmann at the University of Berlin, Fischer was committed to promoting science in Germany and was instrumental in founding the Kaiser Wilhelm Society and establishing the Kaiser Wilhelm Institute for Chemistry and the Kaiser Wilhelm Institute for Physics in Berlin-Dahlem. Fischer was also elected president of the German Chemical Society several times.

His scientific school produced numerous well-known chemists, including Karl Freudenberg, Burckhardt Helferich, Phoebus Levene, Walter Abraham Jacobs, Hermann Leuchs, Ludwig Knorr, Max Bergmann and the later Nobel Prize winners Otto Diels, Otto Warburg and Karl Landsteiner.

Origin and family

Emil Fischer grew up in Euskirchen as the last-born and only son next to five sisters of Laurenz Fischer (1807-1902) and his wife Julie Poensgen (1819-1882), aunt of the Düsseldorf industrialist Carl Poensgen. In February 1888 he married Agnes Gerlach (c. 1861-12 November 1895) in Erlangen, daughter of the local anatomy professor Joseph von Gerlach. The couple had three children: the future chemist Hermann Fischer (December 16, 1888-March 9, 1960), Walter (July 5, 1891-November 4, 1916), and Alfred (October 3, 1894-March 29, 1917).

Career

Emil Fischer graduated from the Bonn Gymnasium in 1869 as a first-year student. At first he wanted to study mathematics and physics, but this was rejected by his father, who regarded the subjects as too abstract and a breadless art. Fischer dropped out of a merchant apprenticeship to study chemistry at the University of Bonn from Easter 1871, among others under August Kekulé. He himself cited "complete lack of talent" as the reason for dropping out; some biographers cite health reasons, but it also seems to have involved a father-son conflict. His father, who was a successful entrepreneur in the timber business and aspired to a commercial career for his only son, is said to have said afterwards: "The boy is too stupid to be a merchant, he should study".

Starting in the fall semester of 1872, Fischer studied in Strasbourg, where he earned his doctorate in 1874 under Adolf von Baeyer on the acylation of phenolphthalein dyes with Ueber Fluorescëin and Phtalëin-Orcin, after he had had to abandon his first doctoral topic because an important piece of equipment had broken while he was experimenting. While still a student, one of his lecturers, the chemist Friedrich Rose, was so impressed by his analytical skills that he commissioned the young student to analyze the water of a mineral spring in Upper Alsace. With a thesis on hydrazines, he was habilitated in Munich in 1878, and appointed professor of analytical chemistry there as early as 1879. After a stopover in Erlangen (1882-1884), he became head of the institute in Würzburg in 1885 (1885-1892). His cousin Otto Fischer took over the chair in Erlangen. According to plans by Emil Fischer, the new building at Pleicherring 11 (today Röntgenring) with an attached service villa was built in Würzburg. In 1892, however, he followed the highly remunerated call to Berlin as successor to August Wilhelm Hofmann, who had died unexpectedly. Arthur Hantzsch became his successor in Würzburg in 1893, after Theodor Curtius had declined a call in 1892.

Commitment to the First World War

After the outbreak of the First World War, Emil Fischer was one of the first signatories of the Manifesto of the 93 An die Kulturwelt! of October 4, 1914. October 1914, which justified the invasion of Belgium by German troops, denied alleged wartime atrocities committed by German troops in Belgium, reproached the Western opponents of the war for "allying themselves with Russians and Serbs and offering the world the disgraceful spectacle of setting Mongols and Negroes on the white race," and asserted that "without so-called German militarism, German culture would long since have been wiped off the face of the earth." However, he received a reprimand for interfering in internal military affairs for his reference at the beginning of the war, together with Walther Rathenau, to the military necessity of saltpetre production.

During the war, Fischer then belonged to the large number of German Nobel Prize winners and other top researchers who largely oriented their activities to the demands of the war. In October 1914, the Prussian Minister of War, Erich von Falkenhayn, had commissioned Walther Nernst and the artillery expert in the Supreme Army Command, Major Michelis, to ensure an "increase in projectile effectiveness" through ammunition that contained non-lethal irritants. Fischer was soon called in, as were other scientists and representatives of industry, most notably Carl Duisberg, a chemist with a doctorate and longtime acquaintance of Fischer's and, as chairman of the board of Bayer, one of the most powerful German chemical industrialists. From mid-1915, this group unofficially called itself the "Observation and Testing Commission for Blasting and Shooting Tests," abbreviated to "Nernst-Duisberg Commission."

Fischer was allowed to see himself in agreement with colleagues on the enemy side: On October 22, 1914, he sent Duisberg a letter to the editor from The Times in which the Briton William Ramsay, who had received the Nobel Prize in Chemistry two years after him, offered the chemical companies in his country to fill in for a younger chemist so that he could go to the front. Fischer concluded from this: "He will not be surprised that his friends in Germany act in a similar way.

After the firing of substances acting merely as irritants had failed to have sufficient effect at the front, von Falkenhayn turned to Fischer on December 18, 1914, and urged "something" that would "permanently incapacitate people." Fischer did not distance himself from this, but merely saw technical problems: he explained to the minister, as he reported to Duisberg a few days later, how difficult it was to find substances that still had a lethal effect in the heavy dilutions in the battlefield. Despite his skepticism, Fischer conducted preliminary tests with hydrocyanic acid at the end of 1914 in a similar way to Nernst. At Nernst's request, he had even "prepared anhydrous prussic acid" especially for this purpose. However, the preliminary tests were not convincing for either of them.

In any case, in the weeks that followed, Fritz Haber increasingly began to assert himself as the organizer and coordinator of the forces of the military, science and industry, and he was the driving force behind the fact that, contrary to Fischer's assumption, several thousand enemy soldiers did fall for the first time in April 1915 in the Second Battle of Flanders as a result of the release of chlorine gas. Fischer obviously did not see anything reprehensible in this either. On the contrary, he advised his son Hermann on July 13, 1915:

In the following years, the "Haber Office" was to attract more and more top scientists, material-financial resources and political support for research, testing and mass production of chemical warfare agents. Fischer, on the other hand, was not directly active in this field, apart from his early and failed experiment with hydrocyanic acid, even though some authors claim this without giving details, and he was soon on various Entente war crimes lists together with Haber and Nernst, for example.

Fischer was basically in favor of the use of chemical warfare agents and therefore promoted related areas of war research and war economy to the best of his ability. In doing so, he was able to draw on long-standing contacts, especially his good relationship with Duisberg. As early as 1904, Duisberg had tried to recruit Fischer for a syndicate of major German chemical companies. For decades, Fischer was also a prominent member of the German Chemical Society, Duisberg of the Association of German Chemists. In addition, Fischer, together with Nernst and Wilhelm Ostwald, had already tried in 1905 to initiate the foundation of a Chemical Imperial Institute analogous to the existing Physikalisch-Technische Reichsanstalt (PTR) by means of a memorandum and founded an association for this purpose in 1908. Fischer now used such and other long-standing collaborations and contacts for wartime research.

This included, for example, securing sufficient quantities of explosives and thus of their precursor saltpetre. In close coordination with Duisberg, he pushed ahead with an agreement with companies such as Bayer, BASF and Hoechst immediately after the outbreak of war, which was then signed in mid-January 1915. The Berliner Illustrirte Zeitung praised: "Emil Fischer stands by the war raw materials department as a far-sighted advisor." He developed aniline-urea derivatives to stabilize the explosives. In coking plants that processed domestic coal, he encouraged the installation of gas scrubbers that extracted toluene and benzene, thus reducing dependence on imported petroleum for the production of TNT explosive and fuel for the military motor pool. Previously imported natural rubber was increasingly replaced by synthetic methyl rubber thanks to his research.

All in all, Fischer was active in countless committees and institutions of the state, science and industry during the First World War. These included some whose task and composition were kept secret as far as possible, such as the Kaiser Wilhelm Foundation for Wartime Science (KWKW), founded in 1916, where Fischer chaired Specialist Committee I, which dealt with raw materials for ammunition, transport and nutrition issues. The boards of the other five KWKW technical committees included, above all, Haber (Technical Committee II - Chemical Warfare Agents) and Nernst (Technical Committee III - Physics). Not directly related to military issues, on the other hand, were committees such as the "Nutrient Committee" and the "War Committee for Substitute Food," of which Fischer was also a member.

The last years

At the end of the war, Fischer was one of a few top scientists to make it clear that he regretted supporting the 1914 appeal. The war, he said, was "a bad business that must be liquidated." In various letters, he let it be known that he was suffering mentally from Germany's foreseeable defeat and the feared decline of German science. In addition, there were repeated personal strokes of fate: Fischer's wife had died prematurely of meningitis as a result of sinusitis in 1895, six months after the birth of their third child. In addition, there was the early death of two sons: Walter, who, according to his father's account, had been weakened by illness in his youth and had been prematurely discharged from military service in 1910 because of "heart trouble," showed signs of manic-depressive illness by 1913 at the latest. Finally, he took his own life in a closed institution in 1916. Alfred died in 1917 of a typhus infection, which he had contracted during his training as a doctor in a military hospital.

Duisberg claimed in an obituary that Fischer had experienced "a surprising turnaround after the collapse of the Empire. He found the strength for new life and advancement in the research work that immediately began again. The work and its success made him cheerful and happy again". During a meeting only 10 days before his suicide, he had sat "as one of the happiest among us".

However, Fischer's health at the end of the First World War was not only limited by his age, the poor food supply during the war years and hard work. He had also, according to his own account, already had a first illness known as "gastritis" before the age of 18, which was to recur throughout his life and be the reason for several long absences from work. Finally, in his opinion, his many years of unprotected exposure to phenylhydrazine had led to a "chronic poisoning , which appeared in the fall of 1891 and manifested itself in very troublesome disturbances of intestinal activity, namely in nocturnal colics and diarrhea." In the spring of 1918, he fell ill with "cholecystitis" and "pneumonia." In mid-July 1919, after an examination, the surgeon August Bier told him that he had "intestinal cancer". In view of the diagnostic possibilities of the time, the true nature and cause of this (then incurable) disease must remain open. In any case, Fischer sorted out his papers in the following three days, bequeathed a large sum to his son Hermann, transferred the remaining assets to the Academy of Sciences for the promotion of young scientists, and put an end to his life by taking cyanide in the presence of his son and his housekeeper.

Emil Fischer was buried in the New Wannsee Cemetery. The city of Berlin had a representative grave laid out for him on the north wall of the cemetery. The five-meter-long grave wall made of shell limestone is adorned with a relief designed by Fritz Klimsch, which shows a kneeling couple carrying a large handled bowl. By decision of the Berlin Senate, the final resting place of Emil Fischer (grave location Li AT 39) has been dedicated as an honorary grave of the State of Berlin since 1956. The dedication was extended in 2016 by the now customary period of twenty years.

Natural sciences in general

Fischer was a master of the structural elucidation of natural products. Fischer owed the discovery of phenylhydrazine to a coincidence as an internship assistant in Strasbourg. Brown intermediates were obtained in the diazotization carried out by an intern. Fischer investigated the reaction with sodium sulfite and obtained the yellow phenylhydrazine. He wrote his first paper on phenylhydrazine in 1875, and later wrote extensive papers on this compound. With phenylhydrazine, Fischer was also able to distinguish aldehydes and ketones and characterize them as phenylhydrazones.

Sugar Chemistry

Using phenylhydrazine, he was able to derivatize the free carbonyl group of sugars, and later in 1891 he elucidated the configuration of D-glucose, D-mannose, and D-arabinose. The conclusion to the structural elucidation of the sugars is known as Fischer's proof.

The determination of sugar molecules was favored by several discoveries:

In studies of the spatial shape of sugar molecules, Fischer found that sugars crystallize out in the presence of acetone (acetal formation). The crystalline acetone compounds of sugar led to a better spatial understanding of sugar molecules. Of great importance to stereochemistry was the theory of the asymmetric carbon atom according to the theory of Jacobus Henricus van 't Hoff and Joseph Achille Le Bel. Walden's inversion (Paul Walden) at the optically active carbon atom was also demonstrated in sugar chemistry.

Based on the many findings, he was able to perform a total synthesis of optically active sugars of the mannitol series and edit the nomenclature.

Only when the stereochemistry of the sugars was exact were they transformed by plant and animal bodies, so that Fischer formulated the lock-and-key principle (1894).

Through his work on the stereochemistry of sugars and the optical rotation of sugar solutions, he was able to give van 't Hoff's theory on chirality an appropriate place in organic chemistry. Fischer nomenclature and a three-dimensional molecular representation method (Fischer projection) were named after Fischer.

Amino acids, peptides

Starting in 1900, Emil Fischer also investigated peptide synthesis. At that time, only 14 amino acids were known, but by 1907 there were already 19. Fischer obtained the amino acid proline from casein.

In Fischer's group, about 100 peptides were produced. In later years, his student E. Abderhalden significantly improved peptide synthesis.

In 1902, at the Assembly of German Natural Scientists and Physicians in Karlsbad, he was the first to propose, independently and simultaneously with Franz Hofmeister, a structure of proteins consisting of amino acids with peptide bonds. At the same time, he introduced the name peptide at that time.

Fischer was the first to study spider silk (1907). He found that it consisted of amino acids, but quite different from silk from silkworms.

More discoveries

Other significant contributions of his working group were Fischer's indole synthesis (1883) and Fischer's oxazole synthesis, named after him, and the synthesis of the natural products caffeine (1897) and theobromine. Later, Fischer and B. Helferich synthesized nucleosides and nucleotides. While researching uric acid, Fischer discovered the nucleic acid building block purine as a base in 1884.

In the chemical industry, phenylhydrazine, discovered by Fischer in 1875 as an assistant to Baeyer, was used to produce drugs and dyes. Antipyrine, a first important drug in the chemical industry, was a condensation product of phenylhydrazine and acetic ester and had been developed by his student Ludwig Knorr. The production of the dye tartrazine became possible with phenylhydrazine.

Fischer, together with his nephew Alfred Dilthey, synthesized the diethyl-barbituric acid barbital (Veronal) in 1902. Since the substance showed toxic side effects in higher doses, it was unsuitable as an anesthetic, but was used as a strong sedative before operations (for premedication). Veronal and its derivative phenobarbital were used as sleeping pills until the 1980s; phenobarbital continues to be used worldwide in the treatment of epilepsy under the trade name Luminal.

In 1894, he discovered the principle of asymmetric induction (a chiral center determines the chirality of the neighboring carbon atom) at Brucin.

Teacher, promoter and organizer

In 1900, he inaugurated a large new building for the Organic Institute of the Friedrich Wilhelm University in Berlin. Fischer demanded serious scientific and correct work from his students, and he wanted more scientific freedom for highly talented young chemists. Cooperation between science and industry was very important to him. Together with Adolf von Harnack, he was instrumental in founding the Kaiser Wilhelm Society in 1911, of which he was a member of the Senate until his death. Toward the end of the Empire, anti-Semitism increased among scientists as well. Fischer was one of a few who did not join it. He countered the question why he was not anti-Semitic in view of the large number of Jewish competitors:

Fischer also proved to be a nonconformist in another area: Although he initially did not think it made sense for women to study, because they would generally turn to household and family later on after all. Later, however, he changed his mind and was one of the first leading professors to advocate the admission of women to studies, allowing Hertha von Siemens, for example, to work in his private laboratory, and Lise Meitner to work (initially denied) in the institute's laboratory.

His Introductory Organic Lecture has been didactically immortalized by one of his former students, Hans Beyer, in the Textbook of Organic Chemistry and still forms part of the basic canon of organic chemistry.

In 1898 Fischer received the Cothenius Medal of the Leopoldina.

In 1902 he was awarded the Nobel Prize in Chemistry "in recognition of the extraordinary merit he has acquired through his work in the field of sugar and purine groups." In 1904 he was elected to the National Academy of Sciences, in 1908 to the American Academy of Arts and Sciences, and in 1909 to the American Philosophical Society. From 1900 to 1915 he was a corresponding member of the Académie des sciences in Paris. He was an honorary member of the Experimental and Teaching Institute of Brewing.

Even today, the Emil Fischer High School in Euskirchen, the town of his birth, as well as Emil Fischer Strasse in Berlin, Leverkusen and Leuna, the Emil Fischer Center in Erlangen (home to the Institutes of Biochemistry, Pharmacy and Food Chemistry, and Experimental and Clinical Pharmacology and Toxicology) and the Emil Fischer Graduate School, and another high school in Schwarzheide are named after him.

In 1921, Fritz Klimsch created a sandstone monument to Fischer, which was erected near Fischer's former place of work, the I. Chemical Institute of the Friedrich Wilhelm University (now Humboldt University) in Hessische Straße. This sculpture was destroyed during the Second World War. In 1952, Richard Scheibe created a bronze replica, which was placed in the front garden of the former Max Planck Institute for Cell Physiology (dissolved in 1972) on Garystraße in Dahlem. A second casting was made of this sculpture in 1995, which found its place on Robert-Koch-Platz in Berlin-Mitte.

The lecture hall of the former Chemical Institute of the Humboldt University bears the honorary name Emil Fischer Lecture Hall.

In Erlangen, a memorial plaque was erected at the house where he worked from 1882 to 1885. At the Friedrich Alexander University of Erlangen-Nuremberg, there is an Emil Fischer Center, in which several chairs from the field of life sciences have joined forces.

Every two years, the Society of German Chemists awards the Emil Fischer Commemorative Medal for extraordinary achievements in the field of organic chemistry.

In 1976, the Fischer lunar crater was named after him and Hans Fischer.

Since 1993, the Berlin Upper Secondary School for Nutrition and Food Technology has borne the name Emil Fischer School.

On July 12, 2010, a Berlin memorial plaque was unveiled in Berlin-Mitte, Hessische Straße 1.

On October 7, 2014, The Division of the History of Chemistry of the American Chemical Society honored Emil Fischer's publication Ueber die Conformation des Graubenzuckers und seiner Isomeren (On the Conformation of Grape Sugar and its Isomers) as a revolutionary forward-looking and trend-setting publication in 1891 with the "Citation for Chemical Breakthrough Award". His institute in Würzburg at the time was thus named a Historic Site of Chemistry.

His estate is at the University of Berkeley and with microfilm copies in the archive of the Max Planck Society.

In Euskirchen, the town of his birth, the Emil Fischer Gymnasium is named after him; during his school years it was called the Kaiserin-Auguste-Victoria-Gymnasium.

Sources

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5. Lebensdaten, Publikationen und Akademischer Stammbaum von Hermann Emil Fischer bei academictree.org, abgerufen am 6. Februar 2018.
6. ^ Emil Fischer. Aus meinem Leben. Berlin, 1922, pag.10-40
7. (de) « Synthesen in der Zuckergruppe », Ber. dtsch. chem. Ges., vol. 27,‎ 1894, p. 2985-2993 ; 3189-3232.
8. ^ a b "Fellows of the Royal Society". London: Royal Society. Archived from the original on 16 March 2015.
9. ^ Forster, Martin Onslow (1 January 1920). "Emil Fischer memorial lecture". Journal of the Chemical Society, Transactions. 117: 1157–1201. doi:10.1039/CT9201701157.