Wikihermann emil fischer

Krankheiten und Tod [ Bearbeiten Quelltext bearbeiten ]. Ehe und Kinder [ Bearbeiten Quelltext bearbeiten ]. Werk [ Bearbeiten Quelltext bearbeiten ]. Phenylhydrazin [ Bearbeiten Quelltext bearbeiten ]. Zuckerchemie [ Bearbeiten Quelltext bearbeiten ]. Weitere Entdeckungen [ Bearbeiten Quelltext bearbeiten ]. Lehrer [ Bearbeiten Quelltext bearbeiten ].

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Literatur [ Bearbeiten Quelltext bearbeiten ]. Weblinks [ Bearbeiten Quelltext bearbeiten ]. Einzelnachweise [ Bearbeiten Quelltext bearbeiten ]. Julius Springer, Berlin ; archive. Februar Chemischen Instituts. Eine Erkundungsreise. Memento vom There were several conjectures on the constitution of this base but no satisfactory solution until the Fischers succeeded in wikihermann emil fischer that it was a triphenylmethane derivative.

They reduced rosaniline to a colorless derivative, which they called leucaniline and converted, by removal of its nitrogen atoms, into a hydrocarbon of composition C 20 H They carried out similar reactions with pararosaniline from p -toluidine and anilineobtaining a hydrocarbon with the formula C 19 H 16which proved to be identical to triphenylmethane.

In they proved that the rosaniline dyes were homologues and were triamine derivatives of triphenylmethane and its homologues, rosaniline being a derivative of metatolyldiphenylmethane and p -rosaniline of triphenylmethane. Fischer began a study of uric acid and related substances in and continued his investigations untilwhen he achieved the first synthesis of a nucleotide.

These were biologically important substances. Xanthine, hypoxanthine, adenine, and guanine were present in the cell nucleus of animals. Theobromine, caffeine, and theophylline were stimulants in plants. Fischer became the prime investigator in the field, and it is to him that almost all knowledge of the purines is due. He explored the whole series, established their structures, and synthesized about derivatives by Fischer studied the reactions and degradation products of the purines.

In he ventured structural formulas for uric acidcaffeine, theobromine, xanthine, and guanine. He synthesized theophylline and caffeine and uric acid ; but further research convinced him that his structures were incorrect, since his reaction products were not reconcilable to his formulas. In he provided a new set of formulas. He had come to realize that uric acid and related compounds were oxides of a hypothetical base C 5 N 4 H 4which he named purine:.

He proposed that purine was a heterocyclic compound and also proposed the notation system now used in purine chemistry:. Subsequently, he synthesized hypoxanthine, xanthine, theobromine, adenine, and guanine. Finally, in he succeeded in reducing trichloropurine to purine, the parent substance of the class. These researches involved an immense series of preparations and very difficult reactions.

He continued this work, combining it with his research on carbohydrates, and in prepared glucosides of theophylline, theobromine, adenine, hypoxanthine, and guanine. From theophylline-D-glucoside he prepared the first synthetic nucleotide, theophylline-D-glucoside phosphoric acid. His laboratory methods became the basis for the industrial production of caffeine, theophylline, and theobromine.

In he synthesized 5, 5-diethyl-barbituric acid. Under various trade names—Barbital, Veronal, and Dorminal—this compound proved to be a valuable hypnotic. Another commercially valuable purine was phenyl, ethylbarbituric acid, prepared by Fischer in and known as Luminal or phenobarbital. Fischer carried on his purine research simultaneously with his carbohydrate studies and became the prime investigator in both fields.

When he began his carbohydrate studies inthere were four known monosaccharides: two aldohexoses glucose, galactose and two ketohexoses fructose, sorboseall with the formula C 6 H 12 O 6. There were three known disaccharides sucrose, maltose, lactose. The general structure of the simple sugars had been established. Glucose and galactose were straight-chain pentahydroxy aldehydes, and the ketohexoses were straight-chain pentahydroxy ketones.

Fischer in an enormous effort elaborated the complex structures and chemistry of the carbohydrates, synthesized many of them, and established the configurations of the sixteen possible stereoisomers of glucose. In Heinrich Kiliani developed the method of lengthening the carbon chain in sugars by means of the addition of hydrocyanic acid to the carbonyl groupfollowed by hydrolysis and reduction.

Fischer utilized this method to convert pentoses into hexoses, the latter into heptoses, etc. Fischer achieved his first synthesis of a sugar in He wanted to synthesize glyceraldehyde and use it as a starting point for wikihermann emil fischer up the carbon chain in sugars. To prepare glyceraldehyde he combined acrolein dibromide and barium hydroxide:.

With phenylhydrazine he obtained two different osazones and isolated from them two sugars. He proved that these were fructose and sorbose, the first naturally occurring sugars to be synthesized. The reaction of sugars with phenylhydrazine yielded first the hydrazone and then the osazone. Fischer found that glucose, fructose, and mannose formed the same osazone.

Therefore, the three sugars had the same configuration below the second carbon atom. Osazones on hydrolysis with hydrochloric acid eliminate phenylhydrazine and form osones, a new type of glucose derivative, possessing adjacent carbonyl groups. By reducing these, he obtained sugars, although an aldose is converted into a ketose:. At the other end of the carbon chain the primary alcohol could be reduced or oxidized.

Oxidation of this group in glucose gave glucuronic acid ; oxidation of the carbonyl group at the other end of the chain, a gluconic acid; and oxidation at both sites, a dicarboxylic acid. By differential reductions and oxidations Fischer could transfer the carbonyl group from one end of the chain to the other, and by testing the products for their properties and their optical rotation of the plane of polarized light, he could elucidate the structures of his compounds.

By his methods of oxidation, reduction, degradation, addition, etc.

Wikihermann emil fischer

He established the configurations for all members of the Dseries of aldohexoses, i. Fischer prepared several artificial sugars. He had established the structures of the natural pentoses arabinose and xylose. He found that by extending the carbon chain of each of these pentoses he obtained two products. The Kiliani method introduced a new asymmetric atom and therefore two reaction products:.

His descriptions of the chemistry of the carbohydrates and peptides laid the foundations for the science of biochemistry. Fischer began working on a group of compounds that included uric acid and caffeine. He realized that they were all related to a hitherto unknown substance, which he called purine. Over the next few years he synthesized about related compounds, one of which was the first synthetic nucleotide.

These studies led to the synthesis of powerful hypnotic drugs derived from barbituric acids barbiturates. He next turned to the fuchsine then called "rosaniline" magenta dyesand in collaboration with his cousin Otto Fischer, he published papers in and which established that these dyes were derivatives of triphenylmethane. Emil Fischer's next research was concerned with compounds related to uric acid.

Here the ground had been broken by von Baeyer, but Fischer greatly advanced the field of knowledge of the purines. In and he published papers which established the formulae of uric acidxanthinecaffeine achieving the first synthesistheobromine and some other compounds of this group. After purine itself was isolated, a variety of derivatives were prepared, some of which were patented in view of possible therapeutical applications.

Fischer is particularly noted for his work on sugars. Among his early discoveries related to hydrazine was that phenylhydrazine reacted with sugars to form substances which he named osazonesand which, wikihermann emil fischer highly crystalline and readily formed, served to identify such carbohydrates more definitely than had been previously possible.

In the field of enzymology, Fischer is known for his proposal of "the lock and key" model as a mechanism of substrate binding. Fischer was also instrumental in the discovery of barbituratesa class of sedative drugs used for insomnia, epilepsy, anxiety, and anesthesia. Along with the physician Josef von Meringhe helped to launch the first barbiturate sedative, barbitalin By the introduction of new methods, he succeeded in breaking down the complex albumins into amino acids and other nitrogenous compounds, the constitutions of most of which were known, and by bringing about the recombination of these units, he prepared synthetic peptides which approximated to the natural products.

His research group synthesised the first free dipeptide Glycine-Glycine in The 18 amino acid peptide gave the standard responses to tests for proteins used by physiological chemists - a positive Biuret test, precipitation by inorganic salts and cleavage by proteolytic enzymes [ 14 ]. Fischer married Agnes Gerlach in She died seven years later, leaving him a widower with three sons.

The younger two died during their military service in World War I, but the oldest, Hermannbecame an organic chemist. In he put forward the idea to create the International Atomic Weights Commission. Behrman, Springer Verlag, Contents move to sidebar hide. Article Talk. Read Edit View history. Tools Tools. Download as PDF Printable version.

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