Fluoroantimonic acid

Fluoroantimonic acid

Chembox new
Name = Fluoroantimonic acid
ImageFile = Fluoroantimonic-acid-3D-vdW.png ImageName = Fluoroantimonic acid
IUPACName = Fluoroantimonic acid
OtherNames =
Section1 = Chembox Identifiers
CASNo = 16950-06-4

Section2 = Chembox Properties
Formula = HSbF6
MolarMass = 236.808 g/mole
Appearance = colourless syrup
Density = g cm–3
Solubility = decomposes
MeltingPt = °C at mmHg
BoilingPt = decomposes
pKa = −25

Section7 = Chembox Hazards
ExternalMSDS =
MainHazards = corrosive
FlashPt = non-flammable
RPhrases = R39/23/24/25-35
SPhrases =

Section8 = Chembox Related
Function = acids
OtherFunctn = HF
Magic acid
OtherCations = NaPF6, NaSbF6
OtherAnions = HBF4

Fluoroantimonic acid HSbF6 is a mixture of hydrogen fluoride and antimony pentafluoride in various ratios.Olah, G. A.; Prakash, G. K. S.; Wang, Q.; Li, X. “Hydrogen Fluoride–Antimony(V) Fluoride” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.] The 1:1 combination affords the strongest known superacid, which has been demonstrated to protonate even hydrocarbons to afford carbocations and H2.

The reaction of hydrogen fluoride (HF) and SbF5 is exothermic. HF releases its proton (H+), and its conjugate base (F) is sequestered by one of more molecules SbF5 to give the octahedral SbF6. This anion is classified as noncoordinating, because it is both a very weak nucleophile and a very weak base. The proton effectively becomes "naked", which accounts for the system's extreme acidity. Fluoroantimonic acid is 2×1019 (20 quintillion) times stronger than 100% sulfuric acid. The reaction of hydrofluoric acid and antimony pentafluoride proceeds as follows


Two related products have been crystallised from HF-SbF5 mixtures, and both have been analyzed by single crystal X-ray crystallography. These salts have the formulas [H2F+] [Sb2F11] and [H3F2+] [Sb2F11] . In both salts the anion is Sb2F11. [cite journal | author = Mootz, D.; Bartmann, K. | title = The Fluoronium Ions H2F+ and H3F2+: Characterization by Crystal Structure Analysis | journal = Angewandte Chemie, International Edition in English | year = 1988 | volume = 27 | pages = 391–392 | doi = 10.1002/anie.198803911] As mentioned above, SbF6 is classified as weakly basic; the larger monoanion Sb2F11 would be expected to be still weaker.

Comparison with other acids

The following values are based upon the Hammett acidity function. Acidity is indicated by large negative values of H0.
* Fluoroantimonic acid (1990) (H0 Value = −31.3)
* Magic acid (1974) (H0 Value = −19.2)
* Carborane superacid (1969) (H0 Value = −18.0)
* Fluorosulfuric acid (1944) (H0 Value = −15.1)
* Triflic acid (1940) (H0 Value = −14.9)


This extraordinarily strong acid protonates nearly all organic compounds. In 1967, Bickel and Hogeveen showed that HF-SbF5 will remove H2 from isobutane and methane from neopentane: [cite journal | author = Bickel, A. F.; Gaasbeek, C. J.; Hogeveen, H.; Oelderik, J. M.; Platteeuw, J. C. | title = Chemistry and spectroscopy in strongly acidic solutions: reversible reaction between aliphatic carbonium ions and hydrogen | journal = Chemical Communications | year = 1967 | volume = 1967 | pages = 634–5 | doi = 10.1039/C19670000634] [cite journal | author = Hogeveen, H.; Bickel, A. F. | title = Chemistry and spectroscopy in strongly acidic solutions: electrophilic substitution at alkane-carbon by protons | journal = Chemical Communications | year = 1967 | volume = 1967 | pages = 635–6 | doi = 10.1039/C19670000635] :(CH3)3CH + H+ → (CH3)3C+ + H2:(CH3)4C + H+ → (CH3)3C+ + CH4


HF-SbF5 is rapidly and explosively decomposed by water. It reacts with virtually all known solvents. Solvents that have been proven to be compatible with HF-SbF5 are SO2ClF and liquified sulfur dioxide. Chlorofluorocarbons have also been used as solvents. Containers forHF-SbF5 are made of PTFE.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • Acid — This article is about acids in chemistry. For the drug, see Lysergic acid diethylamide. For other uses, see Acid (disambiguation). Acidity redirects here. For the novelette, see Acidity (Novelette). Acids and Bases …   Wikipedia

  • Magic acid — Fluorosulfuric acid antimony pentafluoride 1:1 Other names Magic Acid …   Wikipedia

  • Strong acid — A strong acid is an acid that ionizes completely in an aqueous solution (not in the case of sulfuric acid as it is diprotic), or in other terms, with a p K a < −1.74. This generally means that in aqueous solution at standard temperature and… …   Wikipedia

  • Conjugate acid — Within the Brønsted–Lowry acid base theory (protonic), a conjugate acid is the acid member, HX, of a pair of two compounds that transform into each other by gain or loss of a proton. A conjugate acid can also be seen as the chemical substance… …   Wikipedia

  • Superacid — A superacid is an acid with an acidity greater than that of 100% sulfuric acid, which has a Hammett acidity function ( H 0) of −12. Commercially available superacids include trifluoromethanesulfonic acid (CF3SO3H), also known as triflic acid, and …   Wikipedia

  • Antimony — This article is about the element. For the town, see Antimony, Utah. Not to be confused with Antinomy, a type of paradox. tin ← antimony → tellurium As ↑ Sb ↓ Bi …   Wikipedia

  • Hammett acidity function — The Hammett acidity function is a measure of acidity that is used for very concentrated solutions of strong acids, including superacids. In such solutions, simple approximations such as the Henderson Hasselbalch equation are no longer valid due… …   Wikipedia

  • Antimony pentafluoride — Chembox new ImageFileL1 = Antimony pentafluoride 2D.png ImageSizeL1 = 120px ImageNameL1 = Antimony pentafluoride ImageFileR1 = Antimony pentafluoride monomer 3D balls.png ImageSizeR1 = 120px ImageNameR1 = Antimony pentafluoride IUPACName =… …   Wikipedia

  • Nicholas reaction — The Nicholas reaction is an organic reaction where a dicobalt octacarbonyl stabilized propargylic cation is reacted with a nucleophile. Oxidative demetallation gives the desired alkylated alkyne.[1][2] Several reviews have been published …   Wikipedia

  • Wallach rearrangement — The Wallach rearrangement, named after Otto Wallach, is an organic reaction and a rearrangement reaction converting an aromatic azoxy compound with sulfuric acid to an azo compound with one arene ring substituted by an hydroxyl group in the… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”