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Glaser Coupling
The Glaser coupling is a type of coupling reaction. It is by far one of the oldest coupling reactions and is based on copper compounds like copper(I) chloride or copper(I) bromide and an additional oxidant like air. The base used in the original research paper is ammonia and the solvent is water or an alcohol. The reaction was first reported by in 1869. He suggested the following process on his way to diphenylbutadiyne: :CuCl + PhC2H + NH3 → PhC2Cu + NH4Cl :4PhC2Cu + O2 → 2PhC2C2Ph + 2Cu2O Modifications Eglinton reaction In the related Eglinton reaction two terminal alkynes are coupled by a copper(II) salt such as cupric acetate. :2R-\!\!-H -> overset\ce\ce] R-\!\!-\!\!-R The oxidative coupling of alkynes has been used to synthesize a number of natural products. The stoichiometry is represented by this highly simplified scheme: : Such reactions proceed via copper(I)-alkyne complexes. This methodology was used in the synthesis of cyclooctadecanonaene. Another example ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coupling Reaction
In organic chemistry, a coupling reaction is a type of reaction in which two reactant molecules are bonded together. Such reactions often require the aid of a metal catalyst. In one important reaction type, a main group organometallic compound of the type R-M (where R = organic group, M = main group centre metal atom) reacts with an organic halide of the type R'-X with formation of a new carbon–carbon bond in the product R-R'. The most common type of coupling reaction is the cross coupling reaction. Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki were awarded the 2010 Nobel Prize in Chemistry for developing palladium-catalyzed cross coupling reactions. Broadly speaking, two types of coupling reactions are recognized: *Homocouplings joining two identical partners. The product is symmetrical *Heterocouplings joining two different partners. These reactions are also called cross-coupling reaction In organic chemistry, a cross-coupling reaction is a reaction where tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimethylsilylacetylene
Trimethylsilylacetylene is the organosilicon compound with the formula . A colorless liquid, "tms acetylene", as it is also called, is used as a source of anion in organic synthesis. Use Trimethylsilylacetylene is used in Sonogashira couplings as the equivalent of acetylene. Using this protected alkyne, as opposed to acetylene itself, prevents further coupling reactions. The trimethylsilyl group can then be cleaved off with TBAF or DBU to form phenylacetylene derivatives. Trimethylsilylacetylene is also used to synthesize diphenylacetylene derivatives in a one-pot Sonogashira coupling, in which the phenylacetylene derivative reacts with a second aryl halide after in-situ deprotection. A less expensive alternative reagent is 2-methylbut-3-yn-2-ol, which after alkynylation is deprotected with base. Trimethylsilylacetylene is commercially available. It may also be prepared in a manner similar to other silyl compounds: deprotonation of acetylene with a Grignard reagent, fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fritsch–Buttenberg–Wiechell Rearrangement
The Fritsch–Buttenberg–Wiechell rearrangement, named for Paul Ernst Moritz Fritsch (1859–1913), Wilhelm Paul Buttenberg, and Heinrich G. Wiechell, is a chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ... whereby a 1,1-diaryl-2-bromo-alkene rearrangement reaction, rearranges to a 1,2-diaryl-alkyne by reaction with a strong base such as an alkoxide. This rearrangement is also possible with alkyl substituents. Reaction mechanism The strong base deprotonates the vinylic hydrogen, which after alpha elimination forms a Vinyl group, vinyl carbene. A 1,2-aryl migration forms the 1,2-diaryl-alkyne product. The mechanism of the FBW rearrangement was a subject of on-surface studies where the vinyl radical was visualised with sub-atomic resolution. Scope One study ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper(I) Acetylide
Copper(I) acetylide, copper carbide or cuprous acetylide, is a chemical compound with the formula . It is a copper(I) salt of acetylene. It consists of cations and acetylide anions , with the triple bond between the two carbon atoms. Although never characterized by X-ray crystallography, the material has been claimed at least since 1856. One form is claimed to be a monohydrate with formula . Copper(I) acetylide is a reddish-brown explosive powder. Synthesis Materials purported to be copper acetylide can be prepared by treating acetylene with a solution of copper(I) chloride and ammonia: : This reaction produces a reddish solid precipitate. Properties When dry, copper acetylide is a heat and shock sensitive primary explosive, more sensitive than silver acetylide. In acetylene manufacturing plants, copper acetylide is thought to form inside pipes made of copper or an alloy with high copper content, which may result in violent explosion. This led to abandonment of copper as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Castro–Stephens Coupling
The Castro–Stephens coupling is a cross coupling reaction between a copper(I) acetylide and an aryl halide in pyridine, forming a disubstituted alkyne and a copper(I) halide. : The reaction was described in 1963 by chemists Castro and Stephens. The reaction is similar to the much older Rosenmund–von Braun synthesis (1914) between aryl halides and copper(I) cyanide and was itself modified in 1975 as the Sonogashira coupling by adding a palladium catalyst and preparing the organocopper compound ''in situ'', allowing copper to also be used catalytically. A typical reaction diphenylacetylene is obtained by the coupling of iodobenzene with Cuphenylacetylene, C2C6H5 in hot pyridine: : Unlike the Sonogashira coupling, the Castro–Stephens coupling can produce heterocyclic compounds when a nucleophilic group is ''arene substitution pattern, ortho'' to the aryl halide, although this typically requires use of dimethylformamide (DMF) as solvent. : References {{DEFAULTSORT:Cas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonogashira Coupling
The Sonogashira reaction is a cross-coupling reaction used in organic synthesis to form carbon–carbon bonds. It employs a palladium catalyst as well as copper co-catalyst to form a carbon–carbon bond between a terminal alkyne and an aryl or vinyl halide. :* : aryl or vinyl :* R2: arbitrary :* X: I, Br, Cl or OTf The Sonogashira cross-coupling reaction has been employed in a wide variety of areas, due to its usefulness in the formation of carbon–carbon bonds. The reaction can be carried out under mild conditions, such as at room temperature, in aqueous media, and with a mild base, which has allowed for the use of the Sonogashira cross-coupling reaction in the synthesis of complex molecules. Its applications include pharmaceuticals, natural products, organic materials, and nanomaterials. Specific examples include its use in the synthesis of tazarotene, which is a treatment for psoriasis and acne, and in the preparation of SIB-1508Y, also known as Altinicline, a nicotinic rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baeyer Indigo Synthesis
Johann Friedrich Wilhelm Adolf von Baeyer (; 31 October 1835 – 20 August 1917) was a German chemist who synthesised indigo and developed a nomenclature for cyclic compounds (that was subsequently extended and adopted as part of the IUPAC organic nomenclature). He was ennobled in the Kingdom of Bavaria in 1885 and was the 1905 recipient of the Nobel Prize in Chemistry.''Adolf von Baeyer: Winner of the Nobel Prize for Chemistry 1905 '' Armin de Meijere Angewandte Chemie International Edition Volume 44, Issue 48, Pages 7836 – 7840 2005''Abstract/ref> Family and education Baeyer was born in Berlin as the son of the noted geodesist and captain of the Royal Prussian Army Johann Jacob Baeyer and his wife Eugenie Baeyer née Hitzig (1807–1843). Both his parents were Lutherans at the time of his birth and he was raised in the Lutheran religion. His mother was the daughter of Julius Eduard Hitzig and a member of the originally Jewish Itzig family, and had converted to Christianit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indigo Dye
Indigo dye is an organic compound with a distinctive indigo, blue color. Indigo is a natural dye obtained from the leaves of some plants of the Indigofera#Uses, ''Indigofera'' genus, in particular ''Indigofera tinctoria''. Dye-bearing ''Indigofera'' plants were once common throughout the world. It is now produced via chemical routes. Blue colorants are rare. Since indigo is insoluble, it is also referred to as a pigment (C.I. Pigment Blue 66, C.I.). Most indigo dye produced today is chemical synthesis, synthetic, constituting around 80,000 tonnes each year, as of 2023. It is most commonly associated with the production of denim cloth and jeans, blue jeans, where its properties allow for effects such as stone washing and stone washing#Acid-washed jeans, acid washing to be applied quickly. Uses The primary use for indigo is as a dye for cotton yarn, mainly used in the production of denim cloth suitable for blue jeans; on average, a pair of blue jeans requires to of dye. Smal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adolf Von Baeyer
Johann Friedrich Wilhelm Adolf von Baeyer (; 31 October 1835 – 20 August 1917) was a German chemist who synthesised indigo dye, indigo and developed a Von Baeyer nomenclature, nomenclature for cyclic compounds (that was subsequently extended and adopted as part of the IUPAC nomenclature of organic chemistry, IUPAC organic nomenclature). He was nobility, ennobled in the Kingdom of Bavaria in 1885 and was the 1905 recipient of the Nobel Prize in Chemistry.''Adolf von Baeyer: Winner of the Nobel Prize for Chemistry 1905 '' Armin de Meijere Angewandte Chemie International Edition Volume 44, Issue 48, Pages 7836 – 7840 2005''Abstract/ref> Family and education Baeyer was born in Berlin as the son of the noted geodesist and captain of the Royal Prussian Army Johann Jacob Baeyer and his wife Eugenie Baeyer née Hitzig (1807–1843). Both his parents were Lutherans at the time of his birth and he was raised in the Lutheran religion. His mother was the daughter of Julius Eduard Hitzig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TMEDA
Tetramethylethylenediamine (TMEDA or TEMED) is a chemical compound with the formula (CH3)2NCH2CH2N(CH3)2. This species is derived from ethylenediamine by replacement of the four amine hydrogens with four methyl groups. It is a colorless liquid, although old samples often appear yellow. Its odor is similar to that of rotting fish. As a reagent in synthesis TMEDA is widely employed as a ligand for metal ions. It forms stable complexes with many metal halides, e.g. zinc chloride and copper(I) iodide, giving complexes that are soluble in organic solvents. In such complexes, TMEDA serves as a bidentate ligand. TMEDA has an affinity for lithium ions. When mixed with n-Butyllithium, ''n''-butyllithium, TMEDA's nitrogen atoms coordinate to the lithium, forming a cluster of higher reactivity than the tetramer or hexamer that ''n''-butyllithium normally adopts. BuLi/TMEDA is able to metallate or even doubly metallate many substrates including benzene, furan, thiophene, ''N''-alkylpyrroles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
