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Topic: Superacid


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In the News (Fri 10 Jul 09)

  
  superacid
A reasonable working definition of superacid, is an acid that is stronger than 100% H2SO4 (Sulphuric Acid).
The F-Al2O3 functionalised heterogeneous catalyst can then be used for a variety of industrial transformations, for example it can be used to produce the current drop-in replacement for CFC-12 (dichlorodifluromethane, that was banned under the Montreal protocol), that is, 1,1,1,2-tetrafluoroethane (HFC-134a) from 2-chloro-1,1,1-trifluoroethane (HCFC-133a) via a Cl for F halogen exchange mechanism.
This is an example of the use of a superacid (HF) in industrial heterogeneous catalysis.
www.chemicalforums.com /index.php?topic=14963.0   (403 words)

  
  Superacids | World of Chemistry
The term superacids was introduced into the chemical literature in 1927 by James Conant and Norris Hall to describe solutions of sulfuric or perchloric acid in glacial acetic acid.
The most common conjugate Brönsted-Lewis superacid is a mixture of fluorosulfuric acid and antimony pentafluoride, known as "Magic Acid." Antimony pentafluoride, a strong Lewis acid, stabilizes fluorosulfate, the deprotonated form of fluorosulfuric acid.
Solid superacids are typically not as strong as liquid phase-conjugate superacids.
www.bookrags.com /research/superacids-woc   (695 words)

  
  Superacid catalyst for the hydroisomerization of n-paraffins - Patent 6495733
Catalysts based on sulfated oxides of zirconium, titanium, iron having superacid characteristics, are known in the art, according to the definition of Gillespie, as described for example by K. Arata, Adv.
The absorption of pyridine causes a consistent shift of this signal and the entity of this shift is correlated to the superacid strength of the material and its catalytic properties.
The sulfate groups are attached to the zirconia by means of the hydroxyls present on its surface, and therefore the possibility of obtaining a monolayer of sulfates, corresponding to the maximum acidity of the material, is linked to the presence of a sufficient number of hydroxyls on the surface of the zirconia.
www.freepatentsonline.com /6495733.html   (2713 words)

  
 Superacid - Wikipedia, the free encyclopedia
A superacid is an acid with an acidity greater than that of 100% sulfuric acid.
The strongest superacids are prepared by the combination of two components, a strong Lewis acid and a strong Brønsted acid.
George A. Olah was awarded the 1994 Nobel prize in chemistry for his investigations of superacids and their use in the direct observation of carbocations.
en.wikipedia.org /wiki/Superacid   (294 words)

  
 Process for generation of free superacid and for imaging, and imaging medium for use therein - Patent 5286612
This "chemical amplification" of the superacid by the secondary acid generator increases the number of moles of acid generated per einstein of radiation absorbed, and thus increases the contrast of the image produced by the present process as compared with simple generation of superacid by a superacid precursor.
The binder used for the layer(s) in which superacid is to be generated must of course be non-basic, such that the superacid is not buffered by the binder.
The heat applied by the rollers 12 causes the superacid present in the exposed regions of the acid-generating layer 16 to cause catalytic breakdown of the secondary acid generator therein, thereby causing formation of a quantity of second acid substantially larger than the quantity of superacid originally generated by the ultra-violet radiation.
www.freepatentsonline.com /5286612.html   (10151 words)

  
 superacid - Search Results - MSN Encarta
A superacid is an acid with an acidity greater than that of 100% sulfuric acid.
Commercially available superacids include trifluoromethanesulfonic acid (CF 3 SO 3 H), also known as triflic acid, and...
The common superacids are made by dissolving a powerful Lewis acid (e.g.
uk.encarta.msn.com /superacid.html   (120 words)

  
 Superacid at AllExperts
A superacid is an acid with an acidity greater than that of 100% sulfuric acid.
In many cases, the superacid is not a single compound, but is instead a system of several compounds that are combined to effect high acidity.
The term superacid was originally coined by James Bryant Conant in 1927 in classifying acids that were stronger than conventional mineral acids.
en.allexperts.com /e/s/su/superacid.htm   (294 words)

  
 Fibers of aligned single-wall carbon nanotubes and process for making the same - Patent # 7125502 - PatentGenius
Superacids useful for making carbon nanotube alewives can be of various types, such as Bronsted superacids, Lewis superacids, and conjugate Bronsted-Lewis superacids.
Lewis superacids includeantimony pentafluoride, arsenic pentafluoride, tantalum pentafluoride and niobium pentafluoride.
Although not meant to be bound by theory, in the presence of 100% sulfuric acid or superacid, the acid species intercalate the individual nanotubes and nanotube bundles.
www.patentgenius.com /patent/7125502.html   (8156 words)

  
 Press Release: The 1994 Nobel Prize in Chemistry
To produce carbocations he used what are termed superacids (acids that are stronger than 100% sulphuric acid).
Superacids are so strong that they can protonate such extremely weak bases as the alkanes, as was shown by Olah and independently by H. Hogeveen.
Superacid catalysis has also made it possible to crack heavy oils and to liquefy coal under surprisingly mild conditions.
nobelprize.org /nobel_prizes/chemistry/laureates/1994/press.html   (1833 words)

  
 Getting the Jump on Superacids [PSC]
Despite their industrial applications, superacids aren't well understood, in large part because they are what they are — extremely strong acids.
Superacids are liquid, and chemistry for 50 or 60 years has had a diversion into the gas phase.
In the case of BF /HF, the weakest superacid, gas-phase experiments indicated a feeble, electrostatic attraction between BF and HF — called a van der Waals attraction.
www.psc.edu /science/Klein2000/getting_jump_on_superacids.html   (1519 words)

  
 Cracking of Lipid Molecules by a Superacid
These lipids (i.e., glycolipids, phospholipids, sphingolipids, etc.) could be cracked with superacids to produce diesel range organics that could be burned in compression ignition engines.
One cracking mechanism proposed in the literature for olefinic compounds is the protonation and generation of relatively stable carbenium ions.
In superacid media, protonation occurs at the C-C or C-H bonding to form a 2-electron, 3-center carbenium ion.
aiche.confex.com /aiche/2006/preliminaryprogram/abstract_59911.htm   (318 words)

  
 NIRE Annual Report 1998
HF with toluene markedly increased desulphurization to 52% mainly from decreases in sulphidic and oxidized sulphur.
The conjugate Bronsted - Lewis superacid HF/7mol% BF3 produced less thiophenic sulphur as well as less oxidized and sulphidic sulphur than did the reaction with HF at 200ºC although the extent of desulphurization was only slightly increased.
In particular, the treated coal, in which almost all sulphidic sulphur was removed, yielded coal of high extractability, indicating that removal of original sulphidic sulphur improves the coal depolymerization.
www.aist.go.jp /NIRE/hist/2000-01-24/annual/1998/17.htm   (354 words)

  
 U.S. Patent: 5780383 - Solid superacid catalyst comprising group VII metal and having H.sub.o less than -18 - *
Solid superacids suitable for catalyzing skeletal isomerizations of butane and isobutane have been prepared by exposing H.sub.4 TiO.sub.4 to 1N sulfuric acid and calcining in air at 500.degree.
The latter two references indicate that addition of Group VIII metal improves the catalytic activities of the solid superacids and that these solid superacids are suitable for isomerization of alkanes and xylenes, and cracking of shale oil or coal to light paraffins.
The catalyst is disclosed as useful in the isomerization of normal alkanes having 4 to 7 carbon atoms per molecule, in alkylation of alkanes and alkylation of aromatics, dehydrogenation or partial oxidation of hydrocarbons and the conversion of alkenes and alcohols to ethers such as methyl tertiary butyl ether.
www.everypatent.com /comp/pat5780383.html   (3116 words)

  
 superacid - Search Results - MSN Encarta
A superacid is an acid with an acidity greater than that of 100% sulfuric acid
How does a superacid actually work at the atomistic level?" Despite their industrial applications, superacids aren't well understood, in large part because they are what...
Click in the field below and highlight all of the HTML code; paste it into your page.
encarta.msn.com /superacid.html   (112 words)

  
 Superacid by Bart Kosko from Nanotime
It is not entirely clear how Kosko uses this term; there are actual compounds that are referred to as "superacids." A superacid is defined as a "medium having a high acidity, generally greater than that of 100 wt.% sulfuric acid." A compound is sold under the name "magic acid."
Alvarez knew then that he was up against a superacid and that he would lose.
In the book, it appears to be possible to design superacids to work on some materials and ignore others.
www.technovelgy.com /ct/content.asp?Bnum=159   (226 words)

  
 intas 96-0978   (Site not responding. Last check: )
The goal of this project consists in the synthesis of new superacid solids based on III-IV group element oxides; investigation of their physicochemical characteristics, structural, adsorption and catalytic properties for reactions of isomerization.
As a consequence of carrying out this project a set of new superacid solids will be synthesized; new relationships between chemical composition, structure of superacid solids and their acidic properties will be obtained.
These require superacid catalysts and are currently performed in the liquid phase being catalysed by sulfuric, triflic or hydrofluoric acids.
www.intas.be /catalog/961-0978.htm   (692 words)

  
 IV Jornadas Internacionales para la Enseñanza Preuniversitaria y Universitaria de la Química   (Site not responding. Last check: )
For example, it was demonstrated that the electrical conductivity of pure sulfuric acid is predominately associated with the Grotthus chain mechanism of proton transfer, rather than simple transport of H3SO4+ and HSO4- ions.
The new superacids permitted preparation of stable solutions of important intermediate species such as nitronium and acylium ions, and carbocations.
Superacid media provided the tool for preparing a wide range of polyatomic cations.
www.cneq.unam.mx /jornadas/2ingles/contenido/semablanzas/ronald_gillespie.htm   (922 words)

  
 Superacids: A New Generation
Most superacids are thick, viscous and highly corrosive fluids that are difficult to use.
Decades ago, scientists discovered that superacids could stabilize carbocations so that they could be studied.
An acid is defined as a superacid if it is stronger than 100% sulfuric acid, the strongest classical acid, which is also considered to be a superacid.
www.eurekalert.org /pub_releases/1998-03/UoSC-SANG-300398.php   (637 words)

  
 Walter G. Klemperer, Chemistry
We study inorganic chemistry at the interface between solution and the solid state: the design and synthesis of heterogeneous catalysts from preassembled molecular building blocks, solution chemical processing of ceramic materials with unusual electrical properties, and the fabrication of nanostructured materials on semiconductor surfaces for microelectronic applications.
One current interest is solid superacids and their catalytic activity in alkane isomerization.
It has been known for some time that extremely active solid superacid catalysts may be prepared by precipitating amorphous, hydrated titanium or zirconium dioxide from aqueous solution and treating these reactive materials with with sulfuric acid.
www.scs.uiuc.edu /chem/gklem2.html   (603 words)

  
 HPCwire Article # 100058
Despite their industrial applications, superacids aren't well understood, in large part because they are what they are -- extremely strong acids.
In the case of BF3/HF, the weakest superacid, gas-phase experiments indicated a feeble, electrostatic attraction between BF3 and HF -- called a van der Waals attraction.
The strongest superacid is antimony pentafluoride in hydrogen fluoride (SbF5/HF), and experiments have shown that these solutions conduct electricity better than can be accounted for by ionic diffusion, the normal process by which electrons in solution roam from ion to ion.
www.hpcwire.com /hpc-bin/artread.pl?direction=Previous&articlenumber=100059   (1302 words)

  
 Alkylation process using solid superacid catalyst liquid phase - US Patent 5491278   (Site not responding. Last check: )
Isoparaffins and olefins are alkylated in the liquid phase by contact with a solid superacid such as sulfated zirconia containing heteropolyacids or polyoxoanions.
High octane number blending components for motor fuel and other valuable products are obtained, with important advantages over processes using liquid acid catalysts, and over vapor phase alkylation with solid superacid catalysts.
James Watkins received a patent for confetti "that flutters and darts".
www.patentstorm.us /patents/5491278.html   (161 words)

  
 Defintion of superacid - Chemistry Dictionary   (Site not responding. Last check: )
The common superacids are made by dissolving a powerful Lewis acid (e.g.
In a biochemical context "superacid catalysis" is sometimes used to denote catalysis by metal ions analogous to catalysis by hydrogen ions.
By analogy, a compound having a very high basicity, such as lithium diisopropylamide, is called a "superbase".
www.chemicool.com /definition/superacid.html   (115 words)

  
 Defintion of superacid - Chemistry Dictionary
The common superacids are made by dissolving a powerful Lewis acid (e.g.
In a biochemical context "superacid catalysis" is sometimes used to denote catalysis by metal ions analogous to catalysis by hydrogen ions.
By analogy, a compound having a very high basicity, such as lithium diisopropylamide, is called a "superbase".
www.bonus.com /contour/Chemicool/http@@/www.chemicool.com/definition/superacid.html   (115 words)

  
 (WO/1995/029068) IMAGING MEDIUM AND PROCESS   (Site not responding. Last check: )
The superacid precursor is capable of being decomposed to produce superacid by radiation in a second wavelength range, but is not, in the absence of the sensitizing dye, capable of being decomposed by radiation in the first wavelength range.
The secondary acid generator is capable of acid-catalyzed thermal decomposition by unbuffered superacid to form a secondary acid.
While at least part of the sensitizing dye is in its first form, the medium is imagewise exposed to radiation in the first wavelength range, thereby causing, in the exposed areas of the acid-generating layer, the formation of unbuffered superacid.
www.wipo.int /pctdb/en/wo.jsp?WO=1995/29068   (570 words)

  
 OLAH WINS NOBEL PRIZE FOR SUPERACID RESEARCH
The work recognized by the Nobel Prize committee was his creation of "superacids" – substances billions of times more acidic than even the strongest conventional acids – and his pioneering use of them in exploring chemical reactions that involve hydrocarbons.
But to control hydrocarbon reactions and increase their yields, chemists must know the geometry and properties of these carbocations in intimate detail.
Superacids make this study possible by allowing scientists to, in effect, freeze the reaction in its tracks.
www.usc.edu /uscnews/stories/889.html   (789 words)

  
 [No title]   (Site not responding. Last check: )
Dr. Dean M. Roddick, Department of Chemistry, University of Wyoming, is supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division for the study of the organometallic chemistry of fluoroalkylphosphine transition metal complexes in acid and superacid media.
Based on the results of this portion of the project, the chemistry will be extended to solution and solid superacid media.
However, organometallic compounds, which are important laboratory and commercial catalysts and reagents, often are not stable in acidic environments.
www.cs.utexas.edu /ftp/pub/inderjit/Data/Text/nsf/9615985   (190 words)

  
 UBC Chemistry Personnel - Felix Aubke
We have been interested in rece nt years in the development and study of new conjugate superacids systems and their application to unsolved synthetic problems.
From recent structural studies we have learned how superacid anions e.g.
The application of superacid media, in particular of liquid antimony(V) fluoride, the strongest Lewis acid has led, via 'naked' metal cations in an acidic matrix, to the discovery of a new class of s-bonded homoleptic carbonyl cations of electron rich metals.
www.chem.ubc.ca /personnel/faculty/aubke   (259 words)

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