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Cyclophane
In organic chemistry, a cyclophane is a hydrocarbon consisting of an aromatic unit (typically a benzene ring) and a Catenation, chain that forms a bridge (chemical), bridge between two non-adjacent positions of the aromatic ring. More complex derivatives with multiple aromatic units and bridges forming cagelike structures are also known. Cyclophanes are well-studied examples of Strain (chemistry), strained organic compounds. [n]-Cyclophanes Structures Paracyclophanes adopt the boat conformation normally observed in cyclohexanes. Smaller value of n lead to greater distortions. X-ray crystallography on '[6]paracyclophane' shows that the aromatic bridgehead carbon atom makes an angle of 20.5° with the plane. The benzyl carbons deviate by another 20.2°. The carbon-to-carbon bond length alternation has increased from 0 for benzene to 39 picometer, pm. Despite their distorted structures, cyclophanes retain their aromaticity, as determined by UV-vis spectroscopy. Reactivity With re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superphane
Superphane is a 6-fold bridged cyclophane with all arene positions in the benzene dimer taken up by ethylene spacers. The compound has been of some scientific interest as a model for testing aromaticity and was first synthesised by Virgil Boekelheide in 1979. Superphane is the base compound for a large group of derivatives with structural variations. The analogs with 2 to 5 bridges are also known compounds. The benzene rings have been replaced by other aromatic units, such as those based on ferrocene or stabilized cyclobutadiene. Numerous derivatives are known with variations in the type and length of the bridging units. Synthesis The first synthesis of superphane itself by Boekelheide involved forming pairs of bridging units. At each stage, two ''o''-chloromethyl toluene structures are pyrolysis, pyrolyzed to form ''o''-xylylenes, either directly or via benzocyclobutene intermediates. Upon further pyrolysis, these each undergo electrocyclic reaction, electrocyclic ring-opening to f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromatic
In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugation alone. The earliest use of the term was in an article by August Wilhelm Hofmann in 1855. There is no general relationship between aromaticity as a chemical property and the olfaction, olfactory properties of such compounds. Aromaticity can also be considered a manifestation of cyclic delocalization and of Resonance (chemistry), resonance. This is usually considered to be because electrons are free to cycle around circular arrangements of atoms that are alternately single- and double-covalent bond, bonded to one another. This commonly seen model of aromatic rings, namely the idea that benzene was formed from a six-membered carbon ring with alternating single and double bonds (cyclohexatriene), was developed by Friedrich August Kekulé ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromaticity
In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugation alone. The earliest use of the term was in an article by August Wilhelm Hofmann in 1855. There is no general relationship between aromaticity as a chemical property and the olfactory properties of such compounds. Aromaticity can also be considered a manifestation of cyclic delocalization and of resonance. This is usually considered to be because electrons are free to cycle around circular arrangements of atoms that are alternately single- and double- bonded to one another. This commonly seen model of aromatic rings, namely the idea that benzene was formed from a six-membered carbon ring with alternating single and double bonds (cyclohexatriene), was developed by Kekulé (see History section below). Each bond may be seen as a hybrid of a single bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethyl Acetylenedicarboxylate
Ethane ( , ) is a naturally occurring organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining. Its chief use is as feedstock for ethylene production. The ethyl group is formally, although rarely practically, derived from ethane. History Ethane was first synthesised in 1834 by Michael Faraday, applying electrolysis of a potassium acetate solution. He mistook the hydrocarbon product of this reaction for methane and did not investigate it further. The process is now called Kolbe electrolysis: : CH3COO− → CH3• + CO2 + e− : CH3• + •CH3 → C2H6 During the period 1847–1849, in an effort to vindicate the radical theory of organic chemistry, Hermann Kolbe and Edward Frankland produced ethane by the reductions of propionitrile ( ethyl cyanide) and ethyl iodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rearrangement Reaction
In organic chemistry, a rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another atom in the same molecule, hence these reactions are usually intramolecular. In the example below, the substituent R moves from carbon atom 1 to carbon atom 2: :\underset\ce\ce\underset\ce\ce Intermolecular rearrangements also take place. A rearrangement is not well represented by simple and discrete electron transfers (represented by curved arrows in organic chemistry texts). The actual mechanism of alkyl groups moving, as in Wagner–Meerwein rearrangement, probably involves transfer of the moving alkyl group fluidly along a bond, not ionic bond-breaking and forming. In pericyclic reactions, explanation by orbital interactions give a better picture than simple discrete electron transfers. It is, nevertheless, possible to draw the curved ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver Perchlorate
Silver perchlorate is the chemical compound with the formula AgClO4. This white solid forms a monohydrate and is mildly deliquescent. It is a useful source of the Ag+ ion, although the presence of perchlorate presents risks. It is used as a catalyst in organic chemistry. Production Silver perchlorate is created by heating a mixture of perchloric acid with silver nitrate. Alternatively, it can be prepared by the reaction between barium perchlorate and silver sulfate, or from the reaction of perchloric acid with silver oxide. Solubility Silver perchlorate is noteworthy for its solubility in aromatic solvents such as benzene (52.8 g/L) and toluene (1010 g/L). In these solvents, the silver cation binds to the arene, as has been demonstrated by X-ray crystallographic studies on crystals obtained from such solutions. Its solubility in water is extremely high, up to 500 g per 100 mL water. X-ray diffraction experiments show that aqueous solutions contain g(H2O)2sup>+ with Ag-O d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbene
In organic chemistry, a carbene is a molecule containing a neutral carbon atom with a Valence (chemistry), valence of two and two unshared valence electrons. The general formula is or where the R represents substituents or hydrogen atoms. The term "carbene" may also refer to the specific compound , also called methylene radical, methylene, the parent hydride from which all other carbene compounds are formally derived. There are two types of carbenes: singlet state, singlets or triplet state, triplets, depending upon their electronic structure. The different classes undergo different reactions. Most carbenes are extremely reactive and short-lived. A small number (the diHalogen, halocarbenes, carbon monoxide, and carbon monosulfide) can be isolated, and can stabilize as Coordination complex, metal ligands, but otherwise cannot be stored in bulk. A rare exception are the persistent carbenes, which have extensive application in modern organometallic chemistry. Generatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrolysis
Pyrolysis is a process involving the Bond cleavage, separation of covalent bonds in organic matter by thermal decomposition within an Chemically inert, inert environment without oxygen. Etymology The word ''pyrolysis'' is coined from the Greek language, Greek-derived morpheme, elements ''pyro-'' (from Ancient Greek : - "fire, heat, fever") and ''lysis'' ( : - "separation, loosening"). Applications Pyrolysis is most commonly used in the treatment of organic compound, organic materials. It is one of the processes involved in the charring of wood or pyrolysis of biomass. In general, pyrolysis of organic substances produces volatile products and leaves Char (chemistry), char, a carbon-rich solid residue. Extreme pyrolysis, which leaves mostly carbon as the residue, is called carbonization. Pyrolysis is considered one of the steps in the processes of gasification or combustion. Laypeople often confuse pyrolysis gas with syngas. Pyrolysis gas has a high percentage of heavy tar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ketone
In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone (where R and R' are methyl), with the formula . Many ketones are of great importance in biology and industry. Examples include many sugars (ketoses), many steroids, ''e.g.'', testosterone, and the solvent acetone. Nomenclature and etymology The word ''ketone'' is derived from ''Aketon'', an old German word for ''acetone''. According to the rules of IUPAC nomenclature, ketone names are derived by changing the suffix ''-ane'' of the parent alkane to ''-anone''. Typically, the position of the carbonyl group is denoted by a number, but traditional nonsystematic names are still generally used for the most important ketones, for example acetone and benzophenone. These nonsystematic names are considered retained IUPAC names, although some introdu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spiro Compound
In organic chemistry, spiro compounds are Organic compound, compounds that have at least two Cyclic compound, molecular rings sharing one common atom. Simple spiro compounds are bicyclic (having just two rings). The presence of only one common atom connecting the two rings distinguishes spiro compounds from other bicyclics.For all four categories, see The specific chapters can be found aan respectively, same access date. For the description featuring adjacent atoms for all but the isolated category, see Clayden, op. cit. Spiro compounds may be fully carbocyclic (all carbon) or heterocyclic (having one or more non-carbon atom). One common type of spiro compound encountered in educational settings is a heterocyclic one— the acetal formed by reaction of a diol with a cyclic ketone. The common atom that connects the two (or sometimes three) rings is called the ''spiro atom''. In carbocyclic spiro compounds like spiro[5.5]undecane, the spiro-atom is a quaternary carbon, and as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
