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Capto-dative Effect
The captodative effect is the Chemical stability, stabilization of Radical (chemistry), radicals by a synergistic effect of an Polar effect, electron-withdrawing substituent and an electron-donating substituent. The name originates as the electron-withdrawing group (EWG) is sometimes called the "captor" group, whilst the electron-donating group (EDG) is the "dative" substituent. Olefins with this substituent pattern are sometime described as captodative. Radical reactions play an integral role in several chemical reactions and are also important to the field of polymer science. When EDGs and EWGs are near the radical center, the stability of the radical center increases. The substituents can Chemical kinetics, kinetically stabilize radical centers by preventing molecules and other radical centers from reacting with the center. The substituents thermodynamically stabilize the center by delocalizing the radical ion via resonance (chemistry), resonance. These stabilization mechanisms l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resonance Contributors Of 2-(dimethylamino)propanenitrile Radical
Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximum amplitude response in the system. When this happens, the object or system absorbs energy from the external force and starts vibrating with a larger amplitude. Resonance can occur in various systems, such as mechanical, electrical, or acoustic systems, and it is often desirable in certain applications, such as musical instruments or radio receivers. However, resonance can also be detrimental, leading to excessive vibrations or even structural failure in some cases. All systems, including molecular systems and particles, tend to vibrate at a natural frequency depending upon their structure; when there is very little damping this frequency is approximately equal to, but slightly above, the resonant frequency. When an Oscillation, oscillat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Magnetic Resonance Spectroscopy
Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy or magnetic resonance spectroscopy (MRS), is a Spectroscopy, spectroscopic technique based on re-orientation of Atomic nucleus, atomic nuclei with non-zero nuclear spins in an external magnetic field. This re-orientation occurs with absorption of electromagnetic radiation in the radio frequency region from roughly 4 to 900 MHz, which depends on the Isotope, isotopic nature of the nucleus and increases proportionally to the strength of the external magnetic field. Notably, the resonance frequency of each NMR-active nucleus depends on its chemical environment. As a result, NMR spectra provide information about individual functional groups present in the sample, as well as about connections between nearby nuclei in the same molecule. As the NMR spectra are unique or highly characteristic to individual compounds and functional groups, NMR spectroscopy is one of the most important methods to identify ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free-radical Polymerization
In polymer chemistry, radical polymerization (RP) is a method of polymerization by which a polymer forms by the successive addition of a radical to building blocks (repeat units). Radicals can be formed by a number of different mechanisms, usually involving separate initiator molecules. Following its generation, the initiating radical adds (nonradical) monomer units, thereby growing the polymer chain. Radical polymerization is a key synthesis route for obtaining a wide variety of different polymers and materials composites. The relatively non-specific nature of radical chemical interactions makes this one of the most versatile forms of polymerization available and allows facile reactions of polymeric radical chain ends and other chemicals or substrates. In 2001, 40 billion of the 110 billion pounds of polymers produced in the United States were produced by radical polymerization. Radical polymerization is a type of chain polymerization, along with anionic, cationic and coor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic And Biomolecular Chemistry
Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product of decay, or is composed of organic compounds * Organic compound, a compound that contains carbon ** Organic chemistry, chemistry involving organic compounds Farming, certification and products * Organic farming, agriculture conducted according to certain standards, especially the use of stated methods of fertilization and pest control * Organic certification, accreditation process for producers of organically-farmed products * Organic horticulture, the science and art of growing fruits, vegetables, flowers, or ornamental plants by following the essential principles of organic agriculture * Organic products, "organics": ** Organic food, food produced from organic farming methods and often certified organic according to organic farming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kinetic Isotope Effect
In physical organic chemistry, a kinetic isotope effect (KIE) is the change in the reaction rate of a chemical reaction when one of the atoms in the reactants is replaced by one of its isotopes. Formally, it is the ratio of rate constants for the reactions involving the light (''k'') and the heavy (''k'') isotopically substituted reactants ( isotopologues): KIE = ''k/k''. This change in reaction rate is a quantum effect that occurs mainly because heavier isotopologues have lower vibrational frequencies than their lighter counterparts. In most cases, this implies a greater energy input needed for heavier isotopologues to reach the transition state (or, in rare cases, dissociation limit), and therefore, a slower reaction rate. The study of KIEs can help elucidate reaction mechanisms, and is occasionally exploited in drug development to improve unfavorable pharmacokinetics by protecting metabolically vulnerable C-H bonds. Background KIE is considered one of the most essential ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Between Diels-Alder And Captodative-enhanced Friedel-Crafts Reaction
Comparison or comparing is the act of evaluating two or more things by determining the relevant, comparable characteristics of each thing, and then determining which characteristics of each are similar to the other, which are different, and to what degree. Where characteristics are different, the differences may then be evaluated to determine which thing is best suited for a particular purpose. The description of similarities and differences found between the two things is also called a comparison. Comparison can take many distinct forms, varying by field: To compare things, they must have characteristics that are similar enough in relevant ways to merit comparison. If two things are too different to compare in a useful way, an attempt to compare them is colloquially referred to in English as "comparing apples and oranges." Comparison is widely used in society, in science and the arts. General usage Comparison is a natural activity, which even animals engage in when decidin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahedron Letters
''Tetrahedron Letters'' is a weekly international journal for rapid publication of full original research papers in the field of organic chemistry. According to the ''Journal Citation Reports'', the journal has a 2022 impact factor of 1.8 Indexing ''Tetrahedron Letters'' is indexed in: References See also *''Tetrahedron In geometry, a tetrahedron (: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex (geometry), vertices. The tet ...'' *'' Tetrahedron: Asymmetry'' Chemistry journals Weekly journals Academic journals established in 1959 Elsevier academic journals {{chem-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of The Brazilian Chemical Society
The Journal of the Brazilian Chemical Society (print , eISSN , CODEN JOCSET) is a Brazilian scientific journal in chemistry. It was founded in 1990 and is published by the '' Brazilian Society of Chemistry'' (''Sociedade Brasileira de Química''), located at the Instituto de Química da Universidade de São Paulo. The journal is online, and the full text is freely available. According to the ''Journal Citation Reports'', the journal has a 2014 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a type of journal ranking. Journals with higher impact factor values are considered more prestigious or important within their field. The Impact Factor of a journa ... of 1.129, ranking it 100th out of 157 journals in the category "Chemistry Multidisciplinary". The ' publishes other chemistry journals with the titles '' Química Nova'' and ''Química Nova na Escola'' (QNEsc). The Journal of the Brazilian Chemical Society should not be confoun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2plus2 Cyclodimerisation And Intramolecular Cyclisation Of Captodative Olefins
Plus or PLUS may refer to: Mathematics * Addition * +, the mathematical sign Music * Plus (band), a Japanese pop boy band Albums and EPs * ''+'' (Ed Sheeran album), (pronounced "plus"), 2011 * ''Plus'' (Astrud Gilberto and James Last album), 1986 * ''Plus'' (Autechre album), 2020 * ''Plus'' (Cannonball Adderley Quintet album), 1961 * ''Plus'' (Martin Garrix EP), 2018 * ''Plus'' (Matt Nathanson EP), 2003 Companies * Plus (autonomous trucking) * Plus (British TV channel), run by Granada Sky Broadcasting * PLUS (Dutch supermarket) * Plus (German supermarket) * Plus (interbank network), Visa's ATM and debit card network * Plus (telecommunications Poland), a mobile phone brand * Plus Communication Sh.A, a cellphone company in Albania * Plus Development, a defunct American computer storage manufacturer * PLUS Expressways, concessionaire holder of majority of Malaysian expressways * PLUS Markets, a small stock exchange in London, UK Other uses * , the international call pref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
