Chemical Forums
Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: abcc on December 01, 2006, 08:30:25 AM
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What are the applications of superacid ???
thx ;)
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Google: superacid application
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Thank you very much for your questioni. Actually, I have never heard superacid before. Now I think this link will help you a lot
http://en.wikipedia.org/wiki/Superacid
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Check me on this, but I think that I've heard that superacids are used to create oxonium ions by protonating alcohols
Something like this: R-OH + H+ ? R-OH2+
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A reasonable working definition of superacid, is an acid that is stronger than 100% H2SO4 (Sulphuric Acid). A classical example of a superacid is hydrofluoric acid, or HF. This is a very interesting inorganic acid to study and is one of the best organic and inorganic solvents available other than water.
HF can be used in heterogeneous catalysis, for example, you can functionalise a binary metal-oxide catalyst such as amorphous chromia or gamma-alumina (Al2O3) to produce a catalytically active substance. Evidence suggests that sub-surface insertion of the fluoride anion occurs and facilitates a through-lattice inductive effect that in turn alters the reactivity of Bronsted and Lewis acid sites on the surface of the catalyst.
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.