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Endo-exo Isomerism
In organic chemistry, ''endo''–''exo'' isomerism is a special type of stereoisomerism found in organic compounds with a substituent on a bridged ring system. The prefix ''endo'' is reserved for the isomer with the substituent located closest, or "''syn''", to the longest bridge. The prefix ''exo'' is reserved for the isomer with the substituent located farthest, or "''anti''", to the longest bridge. Here "longest" and "shortest" refer to the number of atoms that comprise the bridge. This type of molecular geometry is found in norbornane systems such as dicyclopentadiene Dicyclopentadiene, abbreviated DCPD, is a chemical compound with formula C10H12. At room temperature, it is a white brittle wax, although lower purity samples can be straw coloured liquids. The pure material smells somewhat of soy wax or camphor .... The terms ''endo'' and ''exo'' are used in a similar sense in discussions of the stereoselectivity in Diels–Alder reactions. References * {{Navbox stereo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistry''. Oxford University Press. pp. 1–15. . Study of structure determines their structural formula. Study of properties includes physical and chemical properties, and evaluation of chemical reactivity to understand their behavior. The study of organic reactions includes the chemical synthesis of natural products, drugs, and polymers, and study of individual organic molecules in the laboratory and via theoretical ( in silico) study. The range of chemicals studied in organic chemistry includes hydrocarbons (compounds containing only carbon and hydrogen) as well as compounds based on carbon, but also containing other elements, especially oxygen, nitrogen, sulfur, phosphorus (included in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stereoisomerism
In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space. This contrasts with structural isomers, which share the same molecular formula, but the bond connections or their order differs. By definition, molecules that are stereoisomers of each other represent the same structural isomer. Enantiomers Enantiomers, also known as optical isomers, are two stereoisomers that are related to each other by a reflection: they are mirror images of each other that are non-superposable. Human hands are a macroscopic analog of this. Every stereogenic center in one has the opposite configuration in the other. Two compounds that are enantiomers of each other have the same physical properties, except for the direction in which they rotate polarized light and how they interact with different optical iso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substituent
A substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. (In organic chemistry and biochemistry, the terms ''substituent'' and ''functional group'', as well as ''side chain'' and '' pendant group'', are used almost interchangeably to describe those branches from the parent structure, though certain distinctions are made in polymer chemistry. In polymers, side chains extend from the backbone structure. In proteins, side chains are attached to the alpha carbon atoms of the amino acid backbone.) The suffix ''-yl'' is used when naming organic compounds that contain a single bond replacing one hydrogen; ''-ylidene'' and ''-ylidyne'' are used with double bonds and triple bonds, respectively. In addition, when naming hydrocarbons that contain a substituent, positional numbers are used to indicate which carbon atom the substituent attaches to when such information is needed to distinguish between isomers. Su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bridged Compounds
In chemistry, a bicyclic molecule () is a molecule that features two joined rings. Bicyclic structures occur widely, for example in many biologically important molecules like α-thujene and camphor. A bicyclic compound can be carbocyclic (all of the ring atoms are carbons), or heterocyclic (the rings' atoms consist of at least two elements), like DABCO. Moreover, the two rings can both be aliphatic (''e.g.'' decalin and norbornane), or can be aromatic (''e.g.'' naphthalene), or a combination of aliphatic and aromatic (''e.g.'' tetralin). Three modes of ring junction are possible for a bicyclic compound: * In spirocyclic compounds, the two rings share only one single atom, the spiro atom, which is usually a quaternary carbon. An example of a spirocyclic compound is the photochromic switch spiropyran. * In fused/condensed bicyclic compounds, two rings share two adjacent atoms. In other words, the rings share one covalent bond, ''i.e.'' the so-called bridgehead atoms are direc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural or constitutional isomerism, in which ''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 isotopologues. The depth of analysis depends on the field of study or the chemical and physical properties of interest. The English word "isomer" () is a back-for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Geometry
Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometrical parameters that determine the position of each atom. Molecular geometry influences several properties of a substance including its reactivity, polarity, phase of matter, color, magnetism and biological activity. The angles between bonds that an atom forms depend only weakly on the rest of molecule, i.e. they can be understood as approximately local and hence transferable properties. Determination The molecular geometry can be determined by various spectroscopic methods and diffraction methods. IR, microwave and Raman spectroscopy can give information about the molecule geometry from the details of the vibrational and rotational absorbance detected by these techniques. X-ray crystallography, neutron diffraction and electron diffraction can give molecular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Norbornane
Norbornane (also known as bicyclo .2.1eptane) is an organic compound and a saturated hydrocarbon with chemical formula C7H12. It is a crystalline compound with a melting point of 88 °C. The carbon skeleton is derived from cyclohexane ring with a methylene bridge in the 1,4- position, and is a bridged bicyclic compound. The compound is a prototype of a class of strained bicyclic hydrocarbons. The compound was originally synthesized by reduction of norcamphor. The name norbornane is derived from bornane, which is 1,7,7-trimethylnorbornane, being a derivative of camphor (bornanone). The prefix ''nor'' refers to the stripping of the methyl groups from the parent molecule bornane. See also * 2-Norbornyl cation * Norbornene * Norbornadiene * Bornane * endo-Norborneol * exo-Norborneol * Norcamphor Norcamphor is an organic compound, classified as a bicyclic ketone. It is an analog of camphor, but without the three methyl groups. A colorless solid, it is used as a building block ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicyclopentadiene
Dicyclopentadiene, abbreviated DCPD, is a chemical compound with formula C10H12. At room temperature, it is a white brittle wax, although lower purity samples can be straw coloured liquids. The pure material smells somewhat of soy wax or camphor, with less pure samples possessing a stronger acrid odor. Its energy density is 10,975 Wh/l. Dicyclopentadiene is a co-produced in large quantities in the steam cracking of naphtha and gas oils to ethylene. The major use is in resins, particularly, unsaturated polyester resins. It is also used in inks, adhesives, and paints. The top seven suppliers worldwide together had an annual capacity in 2001 of 179 kilotonnes (395 million pounds). Synthesis and structure The spontaneous dimerization of cyclopentadiene at room temperature to form dicyclopentadiene proceeds to around 50% conversion over 24 hours and yields the ''endo'' isomer in better than 99:1 ratio as the kinetically favored product (about 150:1 ''endo'':''exo'' at 80 °C). How ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diels–Alder Reaction
In organic chemistry, the Diels–Alder reaction is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative. It is the prototypical example of a pericyclic reaction with a concerted mechanism. More specifically, it is classified as a thermally-allowed +2cycloaddition with Woodward–Hoffmann symbol π4s_+_π2s.html" ;"title="sub>π4s + π2s">sub>π4s + π2s It was first described by Otto Diels and Kurt Alder in 1928. For the discovery of this reaction, they were awarded the Nobel Prize in Chemistry in 1950. Through the simultaneous construction of two new carbon–carbon bonds, the Diels–Alder reaction provides a reliable way to form six-membered rings with good control over the regio- and stereochemical outcomes. Consequently, it has served as a powerful and widely applied tool for the introduction of chemical complexity in the synthesis of natural products and new materials. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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