Herman Emil Fischer is an outstanding German chemist of the late XIX - early XX century. Laureate of the 1902 Nobel Prize in Chemistry for the study of purines and sugars.
Although his first discovery (phenylhydrazine synthesis) was called by many a mere coincidence, he silenced his critics by regularly repeating them later on. An outstanding German chemist first discovered caffeine, which is the main ingredient in coffee. He defined a class of compounds like him and called them purines.
short biography
Herman Emil Fischer was born on October 9, 1852 in Euskirchen near Cologne. He was the youngest of 5 children and the only boy. His father Lorenz Fischer was a successful businessman. After three years of training with a private teacher, Emil went to a local school, and then spent 2 years at a school in Wetzlar and another 2 in Bonn. He passed his last exam in 1869 and completed his studies with honors. The father wanted his only heir to continue the family business, but after his sonās attempt to engage in entrepreneurial activity failed, he succumbed to his desire to study natural sciences, especially physics. According to the biography of Emil German Fischer, written by him as a Nobel laureate, his father said that he was too stupid to be a businessman, so it would be better if he becomes a student.
In 1871, Emil entered the University of Bonn. There he attended lectures by Kekule, Engelbach and Zinke in chemistry, August Kundt in physics and Paul Grott in mineralogy.
However, in 1872, Emil, who still wanted to study physics, succumbed to the convictions of his cousin Otto Fischer and enrolled with him at the newly created University of Strasbourg, in which Professor Rose worked on the Bunsen analysis method.
Here Emil met Adolf von Bayer, under the influence of which he finally decided to devote his life to chemistry. Studying under his guidance, Fischer studied phthalein dyes discovered by Rose, and in 1874 received a diploma in Strasbourg, defending work on fluorescein and orsine-phthalein.
Academic career
In the same year, Fisher became an assistant at the University of Strasbourg, where he discovered the first hydrazine base (phenylhydrazine) and demonstrated its relationship with hydrazobenzene and sulfonic acid, described by Strecker and Roemer. The discovery of phenylhydrazine, which is believed to be random, was the basis for much of Emil Fischer's later work.
In 1875, von Bayer was offered to take Liebig's place at the University of Munich, and his ward followed him to become his assistant.
In 1878, Emil Fischer received the status of privatocenter in Munich and in 1879 became an assistant professor at the Department of Analytical Chemistry. In the same year he was offered a place in Aix-la-Chapelle, but then refused. In 1881, Fischer became a professor of chemistry at the University of Erlangen, and in 1883 he was asked to lead a laboratory at BASF's Baden aniline-soda factory. Emil, however, thanks to his father, became financially independent and preferred an academic career.
In 1888, a vacancy in chemistry was opened at the University of WĆ¼rzburg, and he held it until 1892, when he was asked to replace A.V. Hoffmann at the department of Berlin University. Here he remained until his death in 1919.
During World War I, a German scientist was active in organizing the chemical resources of Germany and led the commissions for the production of chemicals and food supplies. In peacetime, he helped reorganize the teaching of chemistry and found research centers.
Fisher's work primarily concerns the composition and synthesis of compounds present in the human body. With his research on sugars, enzymes, purines and proteins, he laid the foundations of biochemistry.
Scientific activity
As already mentioned, chemist Herman Emil Fischer discovered phenylhydrazine and used it in later works. He discovered a new group of compounds, considering it to be a derivative of the still unknown compound N 2 H 4 , which he called hydrazine due to its bond with nitrogen. Then Fisher received phenylhydrazine and in 1978 established its formula. He synthesized many organic derivatives of hydrazine and investigated their reactions. For example, a reaction with carbon disulfide allowed to obtain dyes, and oxidation - tetrazines, compounds with chains of 4 nitrogen atoms. Aryl hydrazines with ketones and keto acids formed indole derivatives.
While in Munich, Fischer continued to study hydrazines and, with the help of his cousin, who followed him to Bavaria, developed a new theory of the structure of dyes derived from triphenylmethane and proved it experimentally.
In Erlangen, Fischer studied the active ingredients of tea, coffee and cocoa, namely caffeine and theobromine. He established the composition of a number of compounds of this type, and ultimately synthesized them.
Aniline dyes
Fischer's doctoral dissertation was on the chemistry of colors and dyes. Subsequently, he expanded the scope of his interests to new synthetic dyes. With his cousin Otto, Emil Fischer investigated the composition of rosaniline, the main dye created by August von Hoffmann in 1862 by oxidizing toluidine and aniline. Several assumptions were made about the structure of this base, but there was no satisfactory solution until Fisher was able to show that this is a triphenylmethane derivative. Cousins āāreduced rosaniline to a colorless derivative called leukaninin and converted it by removing nitrogen atoms into a C 20 H 18 hydrocarbon. They conducted similar reactions with pararosaniline (from p-toluidine and aniline), obtaining a hydrocarbon with the formula C 19 H 16 , which turned out to be identical to triphenylmethane. In 1878, they proved that rosaniline dyes are homologues and derivatives of triamine triphenylmethane and its homologs, with rosaniline being a derivative of metatolyldiphenylmethane and p-rosaniline being triphenylmethane.
The discovery of purines
The work that brought fame to organic chemist Emil Fisher was the study of purines and sugars. He did this from 1882 to 1906 and showed that such little-known substances as adenine and xanthine, uric acid and guanine in plant substances, caffeine and animal extracts, belonged to the same family, could be obtained from each other and corresponded to different hydroxyl and amino derivatives of the same basic system formed by a bicyclic nitrogenous structure, which includes the characteristic group of urea. This parent substance, which at first he considered hypothetical, in 1884 he called purine and in 1898 synthesized. Numerous artificial derivatives, more or less similar to natural substances, were obtained in his laboratory between 1882 and 1896.
Fisher sequentially synthesized hypoxanthine, xanthine, theobromine, adenine and guanine. Finally, in 1898, he managed to isolate the main substance, purine, from trichloropurine. This required a lot of preparatory work and very complex reactions. Fisher combined the research of purines with the study of carbohydrates and in 1914 received glucosides of theophylline, theobromine, adenine, hypoxanthine and guanine. From theophylline-D-glucoside, he synthesized the first nucleotide, theophylline-D-glucoside-phosphoric acid.
Fischer's research was of interest to German pharmaceuticals. His laboratory methods became the basis for the industrial production of caffeine, theophylline and theobromine. In 1903, he synthesized 5,5-diethylbarbituric acid. It turned out to be a valuable sleeping pill, which is sold under various trade names (Barbital, Veronal, Dorminal, etc.). Another commercially valuable purine is phenyl, ethyl barbituric acid, obtained by Fisher in 1912 and known as Luminal or phenobarbital.
Sugar research
In 1884, Emil Fischer began his great work on sugars, which changed the understanding of these compounds and created new knowledge, combined into a single whole. The aldehyde formula of glucose was known before 1880, but Fisher established it using a series of transformations, such as oxidation to aldonic acid and exposure to phenylhydrazine discovered by him, which made possible the formation of phenylhydrazones and osazones. By moving to general osasone, he established a connection between glucose, fructose, and mannose, which he discovered in 1888. In 1890, he established the stereochemical nature and isomerization of all known sugars by the epimerization of gluconic and mannoy acids and accurately predicted possible isomers by creatively applying the theory of Van Hoff and Le Bel published in 1874. Fisher realized that glucose, fructose, and mannose are spatial isomers and can be distinguished using the theory of the tetrahedral carbon atom. The known isomers represented only 4 of the 16 possible variants predicted by the Van Goff theory. The mutual synthesis of various hexoses by isomerization, and then pentosis, hexoses and heptosis as a result of the degradation and synthesis reaction, proved the value of the systematics established by him. His greatest success was the production of glucose, fructose and mannose from glycerin in 1890.
This monumental study of sugars, conducted between 1884 and 1894, was expanded by other studies, the most important of which relates to glucosides.
The study of enzymes and proteins
In 1892, mainly thanks to extensive research on sugars and purines, Fischer succeeded Hoffmann as a professor at the University of Berlin, who at that time was Germany's largest and most prestigious chemical institute. With his efforts, Berlin has become one of the world's foremost scientific centers. Fisher led hundreds of students and colleagues from Europe, North America, and Japan.
There, a German chemist began to study enzymes and proteins. An in-depth study of sugars included the process of their conversion by yeast, and he found that of the known stereoisomers of glucose, only some can be broken down by enzymes. Since these isomers differed only in their spatial properties, Fisher came to the conclusion that the enzyme in yeast must also have a certain spatial orientation for interaction with the sugar molecule. Molecular asymmetry is important because it affects the transformation in the body.
Continuing to study carbohydrates, since 1908, Fischer studied tannins, gallic acid, and sugar derivatives. In 1912, he showed that tannins are not glucosides, but esters and synthesize pentadigalloyl glucose, which has the properties of tannin. In 1918, he established the composition of Chinese tannin in the form of pentamethadigalloyl glucose. He also synthesized heptatribenzoylgalloyl-p-iodophenylmaltosazon. This maltose derivative had a molecular weight of 4021, far exceeding that of any synthetic product.
In 1899ā1908 chemist Emil Fisher made a huge contribution to protein knowledge. He sought to analyze effective methods for the separation and identification of individual amino acids, the discovery of their new types, cyclic amino acids proline and oxyproline. Fisher also studied protein synthesis, obtaining various amino acids in optically active form and combining them. He was able to establish the type of bond that would connect them in a chain, namely a peptide bond, and with the help of this he obtained dipeptides, and then tripeptides and polypeptides.
In 1901, in collaboration with Furno, Emil Fischer discovered the synthesis of a dipeptide, glycyl-glycine, and in the same year published his work on the hydrolysis of casein. In laboratory conditions, he received naturally occurring amino acids and discovered new ones. Its synthesis of oligopeptides ended with an octodecapeptide, which possessed many characteristics of natural proteins. This and subsequent work led to a better understanding of proteins and laid the foundations for their further study.
Thus, Fisher participated in determining the chemical structure of enzymes and proteins. He knew that proteins consist of amino acids, but a German scientist suggested that the amino acids in proteins are linked by amide bonds, which he called peptide bonds. He established the presence of this class of molecules in proteins by developing synthetic methods for creating long chains of amino acids. They were held together by peptide bonds and formed substances similar to protein. In 1907, he created a polypeptide with 18 amino acids and showed that it can be destroyed by enzymes in the same way as natural protein.
In addition to this, Fischer studied enzymes and chemicals in lichens, which he found during his frequent trips to the Black Forest, as well as substances used in tanning, and in the last years of his life and fats.
Fisher recognized the complexity of proteins. Even its simple peptides had many isomers, and it was extremely difficult to establish the structure and structure of any protein. By 1905, he differentiated 29 polypeptides and checked their interaction with various enzymes. Fisher characterized proteins by the number, type and arrangement of amino acids. In 1916, he summarized his work on the synthesis of about 100 polypeptides and warned that they represent only a small fraction of the possible combinations that can be found in natural proteins.
Awards
Organic chemist Herman Emil Fischer received the title of Prussian Heheimrat and the honorary titles of the universities of Christiania, Cambridge, Manchester and Brussels. He was also awarded the Prussian Order of Merit and the Bavarian Order of Maximilian āFor Achievements in Art and Scienceā. Emil Fischer received the Nobel Prize for his work on the synthesis of sugar and purine in 1902.
Cause of death
At the age of 18, even before entering Bonn University, Fischer suffered from gastritis, which exacerbated by the end of his stay in Erlangen and forced him to refuse the tempting offer to follow Victor Meyer to the Technical University of Zurich and go on academic leave before he went in 1888 to WĆ¼rzburg. Perhaps this disease caused cancer, due to which he committed suicide on July 15, 1919 in Berlin, taking a large dose of phenylhydrazine.
Personal qualities
Throughout Fisher's life, he was well served by his memory, which allowed him, a not-so-skilled speaker, to memorize the lectures he wrote.
Especially the German chemist was pleased with WĆ¼rzburg, where he enjoyed walks among the hills and often visited the Black Forest. In administrative work, especially after moving to Berlin, Fischer proved himself to be a fighter for creating scientific foundations not only in chemistry, but also in other fields. His keen understanding of the problems of science, his intuition and love of truth, and his persistence in experimentally proving hypotheses made him one of the greatest scientists of all time.
Personal life
In 1888, Herman Emil Fischer married Agnes Gerlach, daughter of Joseph von Gerlach, anatomy teacher in Erlangen. Unfortunately, his wife died 7 years after marriage. They had 3 sons, one of whom died in the First World War, and the other committed suicide at the age of 25 while undergoing compulsory military training. The third son, Otto Lorenz (d. In 1960), became a professor of biochemistry at the University of California, Berkeley.
In 1922, a biography of Herman Emil Fischer was published, which he wrote the year before his death in 1918.
Heritage
After the death of Nobel laureate Herman Emil Fischer in 1919, the German Chemical Society instituted a commemorative medal in his honor. His name is called a series of reactions and concepts.
Fisher's projection is a method of depicting the projection of a molecule in which vertical bonds are removed. A German chemist created it by working on sugars. The Fisher projection formula displays a three-dimensional molecular structure on a two-dimensional surface (for example, paper). Due to this, it became possible to distinguish between right and left-handed D- and L-isomers.
Fisher reaction - a method for the synthesis of indoles from aldehydes or ketones and arylhydrazines.