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Magic Acid
Magic acid (FSO3H·SbF5) is a superacid consisting of a mixture, most commonly in a 1:1 molar ratio, of fluorosulfuric acid (HSO3F) and antimony pentafluoride (SbF5). This conjugate Brønsted–Lewis superacid system was developed in the 1960s by the George Olah lab at Case Western Reserve University, and has been used to stabilize carbocations and hypercoordinated carbonium ions in liquid media. Magic acid and other superacids are also used to catalyze isomerization of saturated hydrocarbons, and have been shown to protonate even weak bases, including methane, xenon, halogens, and molecular hydrogen. History The term "superacid" was first used in 1927 when James Bryant Conant found that perchloric acid could protonate ketones and aldehydes to form salts in nonaqueous solution. The term itself was coined by R. J. Gillespie later, after Conant combined sulfuric acid with fluorosulfuric acid, and found the solution to be several million times more acidic than sulfuric acid alone. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superacid
In chemistry, a superacid (according to the classical definition) is an acid with an acidity greater than that of 100% pure sulfuric acid (), which has a Hammett acidity function (''H''0) of −12. According to the modern definition, a superacid is a medium in which the chemical potential of the proton is higher than in pure sulfuric acid. Commercially available superacids include trifluoromethanesulfonic acid (), also known as triflic acid, and fluorosulfuric acid (), both of which are about a thousand times stronger (i.e. have more negative ''H''0 values) than sulfuric acid. Most strong superacids are prepared by the combination of a strong Lewis acid and a strong Brønsted acid. A strong superacid of this kind is fluoroantimonic acid. Another group of superacids, the carborane acid group, contains some of the strongest known acids. Finally, when treated with anhydrous acid, zeolites (microporous aluminosilicate minerals) will contain superacidic sites within their pores. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perchloric Acid
Perchloric acid is a mineral acid with the formula H Cl O4. Usually found as an aqueous solution, this colorless compound is a stronger acid than sulfuric acid, nitric acid and hydrochloric acid. It is a powerful oxidizer when hot, but aqueous solutions up to approximately 70% by weight at room temperature are generally safe, only showing strong acid features and no oxidizing properties. Perchloric acid is useful for preparing perchlorate salts, especially ammonium perchlorate, an important rocket fuel component. Perchloric acid is dangerously corrosive and readily forms potentially explosive mixtures. History Perchloric acid was first synthesized (together with potassium perchlorate) by Austrian chemist and called "oxygenated chloric acid" in mid-1810s; French pharmacist Georges-Simon Serullas introduced the modern designation along with discovering its solid monohydrate (which he, however, mistook for an anhydride). Production Perchloric acid is produced industrially by two r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raman Spectroscopy
Raman spectroscopy () (named after Indian physicist C. V. Raman) is a spectroscopic technique typically used to determine vibrational modes of molecules, although rotational and other low-frequency modes of systems may also be observed. Raman spectroscopy is commonly used in chemistry to provide a structural fingerprint by which molecules can be identified. Raman spectroscopy relies upon inelastic scattering of photons, known as Raman scattering. A source of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range is used, although X-rays can also be used. The laser light interacts with molecular vibrations, phonons or other excitations in the system, resulting in the energy of the laser photons being shifted up or down. The shift in energy gives information about the vibrational modes in the system. Infrared spectroscopy typically yields similar yet complementary information. Typically, a sample is illuminated with a laser beam. Electr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IR Spectroscopy
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms. It can be used to characterize new materials or identify and verify known and unknown samples. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) which produces an infrared spectrum. An IR spectrum can be visualized in a graph of infrared light absorbance (or transmittance) on the vertical axis vs. frequency, wavenumber or wavelength on the horizontal axis. Typical units of wavenumber used in IR spectra are reciprocal centimeters, with the symbol cm−1. Units of IR wavelength are commonly given in micrometers (formerly called "microns"), symbol μm, which are related to the wavenumber in a reciprocal way. A comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonclassical Ion
Nonclassical carbocations are stabilized by charge delocalization from contributions of neighbouring or bonds, which can form bridged intermediates or transition states. Nonclassical ions have been extensively studied with the 2-norbornyl system, which as “naked” ion unambiguously exhibit such a bridged structure. The landmark of nonclassical ions are unexpectedly fast solvolysis rates and large differences between epimeric esters. Such behaviour is not restricted to 2-norbornyl esters, as has been shown with some cyclopentyl and steroidal esters with the tosyloxy leaving group. Substitution reactions of secondary esters occur by SN2- or SN1-like mechanisms. Only in highly polar solvents such as hexafluoroisopropanol (HFIP) of low nucleophilicity one can expect a nearly same uniform SN1-like mechanism. The solvolysis of several cyclopentyl and steroidal esters show that large solvolysis rates and differences between epimers can occur which surpass those of the 2-norborny ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopentyl Cation
Cyclopentane (also called C pentane) is a highly flammable alicyclic hydrocarbon with chemical formula C5H10 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and below the plane. It occurs as a colorless liquid with a petrol-like odor. Its melting point is −94 °C and its boiling point is 49 °C. Cyclopentane is in the class of cycloalkanes, being alkanes that have one or more rings of carbon atoms. It is formed by cracking cyclohexane in the presence of alumina at a high temperature and pressure. It was first prepared in 1893 by the German chemist Johannes Wislicenus. Production, occurrence and use Cycloalkanes are formed by catalytic reforming. For example, when passed over a hot platinum surfact, 2-methylbutane converts into cyclopentane. Cyclopentane has no particular use. No commercial products are made from cyclopentane itself. As a volatile hydrocarbon it is an incidental component of some fuels and bl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclohexane
Cyclohexane is a cycloalkane with the molecular formula . Cyclohexane is non-polar. Cyclohexane is a colorless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclohexane is mainly used for the industrial production of adipic acid and caprolactam, which are precursors to nylon. Cyclohexyl () is the alkyl substituent of cyclohexane and is abbreviated Cy. Production Modern On an industrial scale, cyclohexane is produced by hydrogenation of benzene in the presence of a Raney nickel catalyst. Producers of cyclohexane account for approximately 11.4% of global demand for benzene. The reaction is highly exothermic, with ΔH(500 K) = -216.37 kJ/mol. Dehydrogenation commenced noticeably above 300 °C, reflecting the favorable entropy for dehydrogenation. : Early Unlike benzene, cyclohexane is not found in natural resources such as coal. For this reason, early investigators synthesized their cyclohexane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewis Dot Structures
Lewis structures, also known as Lewis dot formulas, Lewis dot structures, electron dot structures, or Lewis electron dot structures (LEDS), are diagrams that show the chemical bonding, bonding between atoms of a molecule, as well as the lone pairs of electrons that may exist in the molecule. A Lewis structure can be drawn for any covalently bonded molecule, as well as complex (chemistry), coordination compounds. The Lewis structure was named after Gilbert N. Lewis, who introduced it in his 1916 article ''The Atom and the Molecule.'' Lewis structures extend the concept of the electron dot diagram by adding lines between atoms to represent shared pairs in a chemical bond. Lewis structures show each atom and its position in the structure of the molecule using its chemical symbol. Lines are drawn between atoms that are bonded to one another (pairs of dots can be used instead of lines). Excess electrons that form lone pairs are represented as pairs of dots, and are placed next to the at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluoroantimonic Acid
Fluoroantimonic acid is a mixture of hydrogen fluoride and antimony pentafluoride, containing various cations and anions (the simplest being and ). This substance is a superacid that can be over a billion times stronger than 100% pure sulfuric acid in terms of its protonating ability measured by Hammett function. It even protonates some hydrocarbons to afford pentacoordinate carbocations ( carbonium ions). Fluoroantimonic acid is corrosive. For example, it cannot be contained directly in glass carboys, as it attacks glass, but can be stored in containers lined with PTFE (Teflon). Chemical composition Fluoroantimonic acid is formed by combining hydrogen fluoride and antimony pentafluoride: :SbF5 + 2 HF + H2F+ The speciation (i.e., the inventory of components) of "fluoroantimonic acid" is complex. Spectroscopic measurements show that fluoroantimonic acid consists of a mixture of HF-solvated protons, –_(such_as_)._Thus,_the_formula_""_is_a_convenient_but_overs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hammett Acidity Function
The Hammett acidity function (''H''0) is a measure of acidity that is used for very concentrated solutions of strong acids, including superacids. It was proposed by the physical organic chemist Louis Plack Hammett and is the best-known acidity function used to extend the measure of Brønsted–Lowry acidity beyond the dilute aqueous solutions for which the pH scale is useful. In highly concentrated solutions, simple approximations such as the Henderson–Hasselbalch equation are no longer valid due to the variations of the activity coefficients. The Hammett acidity function is used in fields such as physical organic chemistry for the study of acid-catalyzed reactions, because some of these reactions use acids in very high concentrations, or even neat (pure).Gerrylynn K. Roberts, Colin Archibald Russell. ''Chemical History: Reviews of the Recent Literature''. Royal Society of Chemistry, 2005. . Definition The Hammett acidity function, ''H''0, can replace the pH in concentrated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formal Charge
In chemistry, a formal charge (F.C. or q), in the covalent view of chemical bonding, is the charge assigned to an atom in a molecule, assuming that electrons in all chemical bonds are shared equally between atoms, regardless of relative electronegativity. In simple terms, formal charge is the difference between the number of valence electrons of an atom in a neutral free state and the number assigned to that atom in a Lewis structure. When determining the best Lewis structure (or predominant resonance structure) for a molecule, the structure is chosen such that the formal charge on each of the atoms is as close to zero as possible. The formal charge of any atom in a molecule can be calculated by the following equation: F = V - L - \frac where ''F'' is the formal charge; ''V'' is the number of valence electrons of the neutral atom in isolation (in its ground state); ''L'' is the number of non-bonding valence electrons on this atom in the molecule; and ''B'' is the total number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magic Acid Structure
Magic or Magick most commonly refers to: * Magic (supernatural), beliefs and actions employed to influence supernatural beings and forces * Ceremonial magic, encompasses a wide variety of rituals of magic * Magical thinking, the belief that unrelated events are causally connected, particularly as a result of supernatural effects * Magic (illusion), the art of appearing to perform supernatural feats Magic(k) may also refer to: Art and entertainment Film and television * ''Magic'' (1917 film), a silent Hungarian drama * ''Magic'' (1978 film), an American horror film * ''Magic'' (soap opera), 2013 Indonesian soap opera * Magic (TV channel), a British music television station Literature * Magic in fiction, the genre of fiction that uses supernatural elements as a theme * ''Magic'' (Chesterton play), 1913 * ''Magic'' (short story collection), 1996 short story collection by Isaac Asimov * ''Magic'' (novel), 1976 novel by William Goldman * ''The Magic Comic'', a 1939–1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
