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Gomberg–Bachmann Reaction
The Gomberg–Bachmann reaction, named for the Russian-American chemist Moses Gomberg and the American chemist Werner Emmanuel Bachmann, is an aryl-aryl coupling reaction via a diazonium salt. : The arene compound (here benzene) is reacted with a diazonium salt in the presence of a base to provide the biaryl through an intermediate aryl radical. For example, ''p''-bromobiphenyl may be prepared from 4-bromoaniline and benzene: : BrC6H4NH2 + C6H6 → BrC6H4−C6H5 The reaction offers a wide scope for both diazonium component and arene component but yields are generally low following the original procedure (less than 40%), given the many side-reactions of diazonium salts. Several improvements have been suggested. One possibility is to employ diazonium tetrafluoroborates in arene solvent together with a phase-transfer catalyst, another is to use 1-aryl-3,3-dialkyltriazenes. Pschorr reaction One intramolecular variation which gives better results is the Pschorr cyclization: : ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moses Gomberg
Moses Gomberg (February 8, 1866 – February 12, 1947) was a chemistry professor at the University of Michigan. He was elected to the National Academy of Sciences and the American Philosophical Society, and served as president of the American Chemical Society. Early life and education He was born in Yelisavetgrad, Russian Empire to a Jewish merchant family. His father was Hershko (Hirsh) Gomberg and his mother was Maryam-Ethel Reznikova. In 1884, the family emigrated to Chicago to escape the pogroms following the assassination of Czar Alexander II. In Chicago he worked at the stockyards while attending Lake High School. In 1886, Moses entered the University of Michigan, where he obtained his B.Sc. in 1890 and his doctorate in 1894 under the supervision of A. B. Prescott. His thesis, titled "''Trimethylxanthine and Some of its Derivatives''", dealt with the derivatization of caffeine. Career Appointed an instructor in 1893, Gomberg worked at the University of Michigan for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intramolecular Reaction
In chemistry, intramolecular describes a Chemical process, process or characteristic limited within the Chemical structure, structure of a single molecule, a property or phenomenon limited to the extent of a single molecule. Relative rates In intramolecular organic reactions, two reaction sites are contained within a single molecule. This configuration elevates the effective concentration of the reacting partners resulting in high reaction rates. Many intramolecular reactions are observed where the intermolecular version does not take place. Intramolecular reactions, especially ones leading to the formation of 5- and 6-membered rings, are rapid compared to an analogous intermolecular process. This is largely a consequence of the reduced entropic cost for reaching the transition state of ring formation and the absence of significant strain associated with formation of rings of these sizes. For the formation of different ring sizes via cyclization of substrates of varying tether ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandmeyer Reaction
The Sandmeyer reaction is a chemical reaction used to synthesize aryl halides from aryl diazonium salts using copper salts as reagents or catalysts. It is an example of a radical-nucleophilic aromatic substitution. The Sandmeyer reaction provides a method through which one can perform unique transformations on benzene, such as halogenation, cyanation, trifluoromethylation, and hydroxylation. The reaction was discovered in 1884 by Swiss chemist Traugott Sandmeyer, when he attempted to synthesize phenylacetylene from benzenediazonium chloride and copper(I) acetylide. Instead, the main product he isolated was chlorobenzene. In modern times, the Sandmeyer reaction refers to any method for substitution of an aromatic amino group via preparation of its diazonium salt followed by its displacement with a nucleophile in the presence of catalytic copper(I) salts. : The most commonly employed Sandmeyer reactions are the chlorination, bromination, cyanation, and hydroxylation reaction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meerwein Arylation
The Meerwein arylation is an organic reaction involving the addition of an aryl diazonium salt (ArN2X) to an electron-poor alkene usually supported by a metal salt. The reaction product is an alkylated arene compound. The reaction is named after Hans Meerwein, one of its inventors who first published it in 1939. An electron-withdrawing group (EWG) on the alkene makes it electron deficient and although the reaction mechanism is unclear, involvement of an aryl radical is presumed after loss of nitrogen in the diazonium salt followed by a free radical addition. In the primary reaction product the intermediate alkyl radical is then captured by the diazonium counterion X which is usually a halogen or a tetrafluoroborate. In a subsequent step an elimination reaction liberates HX (for instance hydrochloric acid) and an aryl vinyl compound is formed. The reaction mechanism from the arene's view ranks as a radical-nucleophilic aromatic substitution. In a general scope a Meerwein aryl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graebe–Ullmann Synthesis
Carbazole is an aromatic heterocyclic organic compound. It has a tricyclic structure, consisting of two six-membered benzene rings fused on either side of a five-membered nitrogen-containing ring. The compound's structure is based on the indole structure, but in which a second benzene ring is fused onto the five-membered ring at the 2–3 position of indole (equivalent to the 9a–4a double bond in carbazole, respectively). Carbazole is a constituent of tobacco smoke. History Carl Graebe and Carl Glaser first isolated the compound from coal tar in 1872. Production Few carbazole production methods are economically viable, due to limited demand. During coal tar distillation, carbazole concentrates in the anthracene distillate and must be removed before anthraquinone production; that waste product is the major industrial carbazole source. Polar compounds (e.g., ketones) selectively precipitate it from the anthracene; a more modern technique is simply selective crystallization fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorenone
Fluorenone is an organic compound with the chemical formula , a ketone with fluorene Moiety (chemistry), moiety. It is bright fluorescent yellow solid. Synthesis and reactions It is synthesised by aerobic oxidation of fluorene: : Fluorenone sustains up to four nitro groups giving 2,4,5,7-tetranitrofluorenone. Applications Several substituted fluorenones are biologically active as antibiotic, anticancer, antiviral, or neuromodulatory compounds. Some substituted azafluorenones are biologically active, such as the naturally occurring antimicrobial compound onychine (1-methyl-4-azafluorenone). The compound 1,8-diazafluoren-9-one is used for fingerprint detection. See also * Fluorenol * :de:Chlorflurenol, Chlorflurenol References {{reflist External linksMaterial Safety Data Sheet Fluorenones, Designer drugs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Current Organic Synthesis
Currents, Current or The Current may refer to: Science and technology * Current (fluid), the flow of a liquid or a gas ** Air current, a flow of air ** Ocean current, a current in the ocean *** Rip current, a kind of water current ** Current (hydrology), currents in rivers and streams ** Convection current, flow caused by unstable density variation due to temperature differences * Current (mathematics), geometrical current in differential topology * Conserved current, a field associated to a symmetry in field theory * Electric current, a flow of electric charge through a medium * Thermal current, a flow of heat through a medium * IBM Current, an early personal information management program * Google Currents ** Google Currents (news app), an app developed by Google that provided electronic access to full-length magazine articles between 2011 and 2013 ** Google Currents (social app), an app developed by Google for internal enterprise communication between 2019 and 2023 * Probabi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chem , a place in Finland
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Chem may refer to: *Chemistry *Chemical * ''Chem'' (journal), a scientific journal published by Cell Press *Post apocalyptic slang for "drugs", medicinal or otherwise in the Fallout video game series. In Ancient Egyptian usage: * ''Khem'' (also spelt ''Chem''), the Egyptian word for "black" *Min (god), in the past erroneously named ''Khem'' CHEM may refer to : *A metabolic panel: for instance, CHEM-7, which is the basic metabolic panel * CHEM-DT, a Canadian television channel See also * Chemo (other) * Kem (other) *Kemi Kemi (; ; ; ) is a cities of Finland, town and municipalities of Finland, municipality of Finland. It is located approximately from the city of Tornio and the Finland–Sweden border, Swedish border. The distance to Oulu is to the south and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pschorr Cyclization
The Pschorr cyclization is a name reaction in organic chemistry, which was named after its discoverer, the Germany, German chemist Robert Pschorr (1868-1930). It describes the intramolecular substitution of aromatic compounds via Aryl diazonium salt, aryldiazonium salts as intermediates and is Catalysis, catalyzed by copper. The reaction is a variant of the Gomberg-Bachmann reaction. The following reaction scheme shows the Pschorr cyclization for the example of phenanthrene: Reaction mechanism In the course of the Pschorr cyclization, a diazotization of the starting compound occurs, so that an aryldiazonium salt is formed as intermediate. For this, sodium nitrite is added to hydrochloric acid to obtain nitrous acid. The nitrous acid is protonated and reacts with another equivalent of nitrous acid to the intermediate 1 which is later used for the diazotization of the aromatic amine: The intermediate 1 reacts in the following way with the starting compound: Intermediate 1 r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Werner Emmanuel Bachmann
Werner Emmanuel Bachmann (November 13, 1901 – March 22, 1951) was an American chemist. Bachmann was born in Detroit, Michigan where he studied chemistry and chemical engineering at Wayne State University and later at the University of Michigan in Ann Arbor nearby. He completed his doctorate under Moses Gomberg and spent the rest of his academic career at the University of Michigan. Bachmann studied physical organic chemistry (rearrangements, free radicals) and organic synthesis. He is considered a pioneer in steroid synthesis, and carried out the first total synthesis of a steroidal hormone, equilenin with Alfred L. Wilds. His name is associated with the Gomberg-Bachmann reaction for the synthesis of diaryl compounds from aryl diazonium chlorides. Bachmann developed a new method for the production of the explosive RDX, which was used by the United States during World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a Wor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
