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Isomerization
In chemistry, isomerization or isomerisation is the process in which a molecule, polyatomic ion or molecular fragment is transformed into an isomer with a different chemical structure. Enolization is an example of isomerization, as is tautomerization. When the activation energy for the isomerization reaction is sufficiently small, both isomers can often be observed and the equilibrium ratio will shift in a temperature-dependent equilibrium with each other. Many values of the standard free energy difference, \Delta G^\circ, have been calculated, with good agreement between observed and calculated data. Examples and applications Alkanes Skeletal isomerization occurs in the cracking process, used in the petrochemical industry to convert straight chain alkanes to isoparaffins as exemplified in the conversion of normal octane to 2,5-dimethylhexane (an "isoparaffin"): : Fuels containing branched hydrocarbons are favored for internal combustion engines for their higher octan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoparaffin
In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula . The alkanes range in complexity from the simplest case of methane (), where ''n'' = 1 (sometimes called the parent molecule), to arbitrarily large and complex molecules, like hexacontane () or 4-methyl-5-(1-methylethyl) octane, an isomer of dodecane (). The International Union of Pure and Applied Chemistry (IUPAC) defines alkanes as "acyclic branched or unbranched hydrocarbons having the general formula , and therefore consisting entirely of hydrogen atoms and saturated carbon atoms". However, some sources use the term to denote ''any'' saturated hydrocarbon, including those that are either monocyclic (i.e. the cycloalkanes) or polycyclic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the existence or possibility of isomers. Isomers do not necessarily share similar chemical property, chemical or physical property, physical properties. Two main forms of isomerism are structural isomerism, structural (or constitutional) isomerism, in which ''chemical bond, bonds'' between the atoms differ; and stereoisomerism (or spatial isomerism), in which the bonds are the same but the ''relative positions'' of the atoms differ. Isomeric relationships form a hierarchy. Two chemicals might be the same constitutional isomer, but upon deeper analysis be stereoisomers of each other. Two molecules that are the same stereoisomer as each other might be in different conformational forms or be different Isotopologue, isotopologues. The depth of analy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during chemical reaction, reactions 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 prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octane Rating
An octane rating, or octane number, is a standard measure of a liquid fuel, fuel's ability to withstand Compression ratio, compression in an internal combustion engine without causing engine knocking. The higher the octane number, the more compression the fuel can withstand before detonating. Octane rating does not relate directly to the power output or the energy content of the fuel per unit mass or volume, but simply indicates the resistance to detonating under pressure without a spark. Whether a higher octane fuel improves or impairs an engine's performance depends on the design of the engine. In broad terms, fuels with a higher octane rating are used in higher-compression Petrol engine, gasoline engines, which may yield higher power for these engines. The added power in such cases comes from the way the engine is designed to compress the air/fuel mixture, and not directly from the rating of the gasoline. In contrast, fuels with lower octane (but higher cetane numbers) are idea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saccharide Chemistry
A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' may differ). This formula does not imply direct covalent bonding between hydrogen and oxygen atoms; for example, in , hydrogen is covalently bonded to carbon, not oxygen. While the 2:1 hydrogen-to-oxygen ratio is characteristic of many carbohydrates, exceptions exist. For instance, uronic acids and deoxy-sugars like fucose deviate from this precise stoichiometric definition. Conversely, some compounds conforming to this definition, such as formaldehyde and acetic acid, are not classified as carbohydrates. The term is predominantly used in biochemistry, functioning as a synonym for saccharide (), a group that includes sugars, starch, and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides, oligosa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta-D-Glucopyranose
Glucose is a sugar with the molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using energy from sunlight. It is used by plants to make cellulose, the most abundant carbohydrate in the world, for use in cell walls, and by all living organisms to make adenosine triphosphate (ATP), which is used by the cell as energy. In energy metabolism, glucose is the most important source of energy in all organisms. Glucose for metabolism is stored as a polymer, in plants mainly as amylose and amylopectin, and in animals as glycogen. Glucose circulates in the blood of animals as blood sugar. The naturally occurring form is -glucose, while its stereoisomer -glucose is produced synthetically in comparatively small amounts and is less biologically active. Glucose is a monosaccharide containing six carbon atoms and an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucose
Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using energy from sunlight. It is used by plants to make cellulose, the most abundant carbohydrate in the world, for use in cell walls, and by all living Organism, organisms to make adenosine triphosphate (ATP), which is used by the cell as energy. In energy metabolism, glucose is the most important source of energy in all organisms. Glucose for metabolism is stored as a polymer, in plants mainly as amylose and amylopectin, and in animals as glycogen. Glucose circulates in the blood of animals as blood sugar. The naturally occurring form is -glucose, while its Stereoisomerism, stereoisomer L-glucose, -glucose is produced synthetically in comparatively small amounts and is less biologicall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olefin Metathesis
In organic chemistry, Olefin Metathesis or Alkene Metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the Bond cleavage, scission and regeneration of carbon-carbon double bonds. Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions. For their elucidation of the reaction mechanism and their discovery of a variety of highly active Catalysis, catalysts, Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock were collectively awarded the 2005 Nobel Prize in Chemistry. Catalysts The reaction requires catalysis, metal catalysts. Most commercially important processes employ heterogeneous catalysis, heterogeneous catalysts. The heterogeneous catalysts are often prepared by in-situ activation of a metal halide (MClx) using organoaluminium or organotin compounds, e.g. combining MClx–EtAlCl2. A typical catalyst support is alumina. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
