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Arene Oxide
In chemistry, an arene oxide is an epoxide of an arene. Two important families of arene oxides are benzene oxides and naphthalene oxides as these are intermediates in the oxidative degradation of benzene and naphthalene, two common pollutants. Benzopyrene is also converted to an epoxide, (+)-benzo yrene-7,8-epoxide. Selected reactions Benzene oxide (C6H6O) exists as an equilibrium mixture with the seven-membered ring oxepin, which has three double bonds. They are valence isomers and in equilibrium via disrotatory 6π ring closing and opening. Arene oxides are highly reactive. Benzene oxide and naphthalene-1,2-oxide hydrate to give dihydroxydihydrobenzene and 1,2-dihydroxydihydronaphthalene, respectively. The hydration is catalyzed by epoxide hydrolase Epoxide hydrolases (EH's), also known as epoxide hydratases, are enzymes that metabolize compounds that contain an epoxide residue; they convert this residue to two hydroxyl residues through an epoxide hydrolysis reaction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ring (chemistry)
In chemistry, a ring is an ambiguous term referring either to a simple cycle of atoms and bonds in a molecule or to a connected set of atoms and bonds in which every atom and bond is a member of a cycle (also called a ring system). A ring system that is a simple cycle is called a monocycle or simple ring, and one that is not a simple cycle is called a polycycle or polycyclic ring system. A simple ring contains the same number of sigma bonds as atoms, and a polycyclic ring system contains more sigma bonds than atoms. A molecule containing one or more rings is called a cyclic compound, and a molecule containing two or more rings (either in the same or different ring systems) is termed a polycyclic compound. A molecule containing no rings is called an acyclic or open-chain compound. Homocyclic and heterocyclic rings A homocycle or homocyclic ring is a ring in which all atoms are of the same chemical element. A heterocycle or heterocyclic ring is a ring containing atoms of at least ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epoxide Hydrolase
Epoxide hydrolases (EH's), also known as epoxide hydratases, are enzymes that metabolize compounds that contain an epoxide residue; they convert this residue to two hydroxyl residues through an epoxide hydrolysis reaction to form diol products. Several enzymes possess EH activity. Microsomal epoxide hydrolase (epoxide hydrolase 1, EH1, or mEH), soluble epoxide hydrolase (sEH, epoxide hydrolase 2, EH2, or cytoplasmic epoxide hydrolase), and the more recently discovered but not as yet well defined functionally, epoxide hydrolase 3 (EH3) and epoxide hydrolase 4 (EH4) are structurally closely related isozymes. Other enzymes with epoxide hydrolase activity include leukotriene A4 hydrolase, Cholesterol-5,6-oxide hydrolase, MEST (gene) (Peg1/MEST), and Hepoxilin-epoxide hydrolase. The hydrolases are distinguished from each other by their substrate preferences and, directly related to this, their functions. Epoxide hydrolase types mEH (EH1), sEH (EH2), EH3, and EH4 isozymes Human ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzene Oxide
Oxepin is an oxygen-containing heterocycle consisting of a seven-membered ring with three double bonds. The parent C6H6O exists as an equilibrium mixture with benzene oxide. The oxepin–benzene oxide equilibrium is affected by the ring substituents. A related dimethyl derivative exists mainly as the oxepin isomer, an orange liquid. Oxepin is an intermediate in the oxidation of benzene by the cytochrome P450 (CYP). Other arene oxide In chemistry, an arene oxide is an epoxide of an arene. Two important families of arene oxides are benzene oxides and naphthalene oxides as these are intermediates in the oxidative degradation of benzene and naphthalene, two common pollutants. B ...s are metabolites of the parent arene. References {{Reflist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valence Isomer
In organic chemistry, two molecules are valence isomers when they are constitutional isomers that can interconvert through pericyclic reactions. Benzene There are many valence isomers one can draw for the C6H6 formula benzene. Some were originally proposed for benzene itself before the actual structure of benzene was known. Others were later synthesized in lab. Some have been observed to isomerize to benzene, whereas others tend to undergo other reactions instead, or isomerize by ways other than pericyclic reactions. Image:Benzene-2D-flat.png, Benzene Image:Historic Benzene Formulae Dewar(1867) V.1.svg, Dewar benzene Image:Prisman2.svg, Prismane Image:Benzvalene.png, Benzvalene Image:Bicycloprop-2-enyl.svg, Bicyclopropenyl Cyclooctatetraene The valence isomers are not restricted to isomers of benzene. Valence isomers are also seen in the series (CH)8. Due to the larger number of units, the number of possible valence isomers is also greater and at least 21: Image:Cyclooctatet ... [...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 first 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] |
Oxepin
Oxepin is an oxygen-containing heterocycle consisting of a seven-membered ring with three double bonds. The parent C6H6O exists as an equilibrium mixture with benzene oxide. The oxepin–benzene oxide equilibrium is affected by the ring substituents. A related dimethyl derivative exists mainly as the oxepin isomer, an orange liquid. Oxepin is an intermediate in the oxidation of benzene by the cytochrome P450 (CYP). Other arene oxide In chemistry, an arene oxide is an epoxide of an arene. Two important families of arene oxides are benzene oxides and naphthalene oxides as these are intermediates in the oxidative degradation of benzene and naphthalene, two common pollutants. ...s are metabolites of the parent arene. References {{Reflist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Equilibrium
In a chemical reaction, chemical equilibrium is the state in which both the reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system. This state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but they are equal. Thus, there are no net changes in the concentrations of the reactants and products. Such a state is known as dynamic equilibrium. Historical introduction The concept of chemical equilibrium was developed in 1803, after Berthollet found that some chemical reactions are reversible. For any reaction mixture to exist at equilibrium, the rates of the forward and backward (reverse) reactions must be equal. In the following chemical equation, arrows point both ways to indicate equilibrium. A and B are reactant chemical species, S and T are p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a Chemical reaction, reaction with other Chemical substance, substances. Chemistry also addresses the nature of chemical bonds in chemical compounds. In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both Basic research, basic and Applied science, applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant growth (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzopyrene
A benzopyrene is an organic compound with the formula C20H12. Structurally speaking, the colorless isomers of benzopyrene are pentacyclic hydrocarbons and are fusion products of pyrene and a phenylene group. Two isomeric species of benzopyrene are benzo 'a''yrene and the less common benzo 'e''yrene. They belong to the chemical class of polycyclic aromatic hydrocarbons. Overview Related compounds include cyclopentapyrenes, dibenzopyrenes, indenopyrenes and naphthopyrenes. Benzopyrene is a component of pitch and occurs together with other related pentacyclic aromatic species such as picene, benzofluoranthenes, and perylene. It is naturally emitted by forest fires and volcanic eruptions and can also be found in coal tar, cigarette smoke, wood smoke, and burnt foods such as coffee. Fumes that develop from fat dripping on blistering charcoal are rich in benzopyrene, which can condense on grilled goods. Benzopyrenes are harmful because they form carcinogenic and mutagenic meta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
