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Cumulene
A cumulene is a compound having three or more ''cumulative'' (consecutive) double bonds. They are analogous to allenes, only having a more extensive chain. The simplest molecule in this class is butatriene (), which is also called simply ''cumulene''. Unlike most alkanes and alkenes, cumulenes tend to be rigid, comparable to polyynes. Cumulene carbenes for ''n'' from 3 to 6 have been observed in interstellar molecular cloud A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, ...s and in laboratory experiments by using microwave and infrared spectroscopy. (The more stable cumulenes are difficult to detect optically because they lack an electric dipole moment.) Cumulenes containing heteroatoms are called heterocumulenes; an example is carbon suboxide. Synthesis The first reporte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterocumulene
A heterocumulene is a molecule or ion containing a chain of at least three double bonds between consecutive atoms, in which one or more atoms in the doubly bonded chain is a heteroatom. Such species are analogous to a cumulene in which the chain of doubly bonded atoms contains only carbon, except that at least one carbon is replaced by a heteroatom. Some authors relax the definition to include species with chains of only two double bonds between consecutive atoms, also known as ''allene, heteroallenes''. Because of the double bond rule, heterocumulenes are rarely isolated. Instead they tend to polymerize. Many are however common in the interstellar medium, where they exist as a dilute gas. Most of the longer ones are very unstable and reactive, and thus have a transient existence, or can only survive when dilute or in an inert matrix. Molecular clouds in space are very dilute and allow heterocumulenes to exist long enough to be detected. Some simple heterocumulenes are common chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cumulenes
A cumulene is a compound having three or more ''cumulative'' (consecutive) double bonds. They are analogous to allenes, only having a more extensive chain. The simplest molecule in this class is butatriene (), which is also called simply ''cumulene''. Unlike most alkanes and alkenes, cumulenes tend to be rigid, comparable to polyynes. Cumulene carbenes for ''n'' from 3 to 6 have been observed in interstellar molecular clouds and in laboratory experiments by using microwave and infrared spectroscopy. (The more stable cumulenes are difficult to detect optically because they lack an electric dipole moment.) Cumulenes containing heteroatoms are called heterocumulenes; an example is carbon suboxide. Synthesis The first reported synthesis of a butatriene is that of tetraphenylbutatriene in 1921. The most common synthetic method for butatriene synthesis is based on reductive coupling of a geminal dihalovinylidene. Tetraphenylbutatriene was reported synthesized in 1977 by homocoupling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allene
In organic chemistry, allenes are organic compounds in which one carbon atom has double bonds with each of its two adjacent carbon atoms (, where R is hydrogen, H or some organyl group). Allenes are classified as diene#Classes, cumulated dienes. The parent compound of this class is propadiene (), which is itself also called ''allene''. A group of the structure is called allenyl, while a substituent attached to an allene is referred to as an allenic substituent (R is H or some alkyl group). In analogy to Allyl group, allylic and Propargyl group, propargylic, a substituent attached to a saturated carbon α (i.e., directly adjacent) to an allene is referred to as an allenylic substituent. While allenes have two consecutive ('cumulated') double bonds, compounds with three or more cumulated double bonds are called cumulenes. History For many years, allenes were viewed as curiosities but thought to be synthetically useless and difficult to prepare and to work with.The Chemistry of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Suboxide
Carbon suboxide, or tricarbon dioxide, is an organic, oxygen-containing chemical compound with formula and structure . Its four cumulative double bonds make it a cumulene. It is one of the stable members of the series of linear oxocarbons , which also includes carbon dioxide () and pentacarbon dioxide (). Although if carefully purified it can exist at room temperature in the dark without decomposing, it will polymerize under certain conditions. The substance was discovered in 1873 by Benjamin Brodie by subjecting carbon monoxide to an electric current. He claimed that the product was part of a series of "oxycarbons" with formulas , namely , , , , …, and to have identified the last two; however, only is known. In 1891 Marcellin Berthelot observed that heating pure carbon monoxide at about 550 °C created small amounts of carbon dioxide but no trace of carbon, and assumed that a carbon-rich oxide was created instead, which he named "sub-oxide". He assumed it was the sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphenylketene
Diphenylketene is a chemical substance of the ketene family. Diphenylketene, like most stable disubstituted ketenes, is a red-orange oil at room temperature and pressure. Due to the successive double bonds in the ketene structure R1R2C=C=O, diphenyl ketene is a heterocumulene. The most important reaction of diphenyl ketene is the [2+2] cycloaddition at C-C, C-N, C-O, and C-S multiple bonds. History Diphenyl ketene was first isolated by Hermann Staudinger in 1905 and identified as the first example of the exceptionally reactive class of ketenes with the general formula R1R2C=C=O (R1=R2=phenyl group). Preparation The first synthesis by H. Staudinger was based on 2-chlorodiphenylacetyl chloride (prepared from benzilic acid and thionyl chloride) from which two chlorine atoms are cleaved with zinc in a Alkene#Elimination reactions, dehalogenation reaction: An early synthesis uses benzilmonohydrazone (from Diphenylethanedione and hydrazine hydrate), which is oxidized with Mercury(I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyyne
A polyyne is any organic compound with alternating Single bond, single and triple bonds; that is, a series of consecutive alkynes, with ''n'' greater than 1. These compounds are also called polyacetylenes, especially in the natural products and chemical ecology literature, even though this nomenclature more properly refers to acetylene polymers composed of alternating single and double bonds with ''n'' greater than 1. They are also sometimes referred to as oligoynes, or carbinoids after "linear acetylenic carbon, carbyne" , the hypothetical allotrope of carbon that would be the ultimate member of the series. In ''Avancés récentes en chimie des acétylènes – Recent advances in acetylene chemistry'' The synthesis of this substance has been claimed several times since the 1960s, but those reports have been disputed. Indeed, the substances identified as short chains of "carbyne" in many early organic synthesis attempts would be called polyynes today. The simplest polyyne is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkene
In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins. The International Union of Pure and Applied Chemistry (IUPAC) Preferred IUPAC name, recommends using the name "alkene" only for Open-chain compound, acyclic hydrocarbons with just one double bond; alkadiene, alkatriene, etc., or polyene for acyclic hydrocarbons with two or more double bonds; cycloalkene, cycloalkadiene, etc. for Cyclic compound, cyclic ones; and "olefin" for the general class – cyclic or acyclic, with one or more double bonds. Acyclic alkenes, with only one double bond and no other functional groups (also known as mono-enes) form a homologous series of hydrocarbons with the general formula with ''n'' being a >1 natural number (which is two hydrogens less than the corresponding alkane). When ''n'' is four or more, isomers are possible, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopropatriene
Cyclopropatriene is a hypothetical compound () which is an allotrope of carbon. It was once proposed as a candidate for a spectroscopically observed tricarbon species. It is a cyclic cumulene A cumulene is a compound having three or more ''cumulative'' (consecutive) double bonds. They are analogous to allenes, only having a more extensive chain. The simplest molecule in this class is butatriene (), which is also called simply ''cumu .... References Allotropes of carbon Hypothetical chemical compounds Three-membered rings Homonuclear triatomic molecules Cyclocarbons Cumulenes {{Hyp-chem-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vinylidene
Methylidenecarbene (systematically named λ2-ethene and dihydrido-1κ2''H''-dicarbon(''C''—''C'')) is an organic compound with the chemical formula (also written [] or ). It is a metastability, metastable proton tautomer of acetylene, which only persists as an adduct. It is a colourless gas that phosphoresces in the far-infrared range. It is the simplest unsaturated carbene. Nomenclature The systematic names ''λ2-ethene'', and ''dihydrido-1κ2H-dicarbon(C—C)'', valid IUPAC names, are constructed according to the substitutive and additive nomenclatures, respectively. In appropriate contexts, methylidenecarbene can be viewed as ethene with two hydrogen atoms removed, or as ethane with four hydrogens removed; and as such, ''ethen-1-ylidene'' (or ''vinylidene'') or ''ethane-1-diylidene'', respectively, may be used as a context-specific systematic names, according to substitutive nomenclature. By default, these names pay no regard to the radicality of the methylidenecarbene m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Bond
In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist between two different elements: for example, in a carbonyl group between a carbon atom and an oxygen atom. Other common double bonds are found in azo compounds (N=N), imines (C=N), and sulfoxides (S=O). In a skeletal formula, a double bond is drawn as two parallel lines (=) between the two connected atoms; typographically, the equals sign is used for this. Double bonds were introduced in chemical notation by Russian chemist Alexander Butlerov. Double bonds involving carbon are stronger and shorter than single bonds. The bond order is two. Double bonds are also electron-rich, which makes them potentially more reactive in the presence of a strong electron acceptor (as in addition reactions of the halogens). File:Ethene structural.svg, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylphosphine
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is versatile compound that is widely used as a reagent in organic synthesis and as a ligand for transition metal complexes, including ones that serve as catalysts in organometallic chemistry. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether. Preparation and structure Triphenylphosphine can be prepared in the laboratory by treatment of phosphorus trichloride with phenylmagnesium bromide or phenyllithium. The industrial synthesis involves the reaction between phosphorus trichloride, chlorobenzene, and sodium: :PCl3 + 3 PhCl + 6 Na → PPh3 + 6 NaCl Triphenylphosphine crystallizes in triclinic and monoclinic modification. In both cases, the molecule adopts a pyramidal structure with propeller-like arrangement of the thre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
