This document discusses superacids and provides examples of some strong superacids. It defines superacids as acids that are stronger than 100% sulfuric acid based on the Hammett acidity function. Some examples of superacids mentioned include fluorosulfuric acid with an H0 of -15.1, carboranes with H0 below -18, and fluoroantimonic acid with H0 between -21 and -23. Magic acid, which is a 1:1 mixture of fluorosulfuric acid and antimony pentafluoride, has the highest acidity of the examples discussed with an H0 of -19.2. Superacids find applications as catalysts in pet

1. Superacids
Hammett acidity Function

2.  According to the classical definition, a super acid is an acid with an acidity greater
than that of 100% pure sulfuric acid, which has Hammett acidity function of -12.
 According to the modern definition, a super acid is a medium in which the
chemical potential of the proton is higher than in pure sulfuric acid.

3.  More efficient proton donor than pure sulphuric acid.
 Viscous, corrosive liquid.
 1018 times more acidic than sulphuric acid.
 Formed when powerful Lewis acid is dissolved in a powerful Bronsted acid.

4. HAMMETT ACIDITY FUNCTION:
 Is a measure of acidity that is used for very concentrated solution of strong acid,
including super acid.
 Proposed by the physical organic chemist
Louis Plack Hammett.
 H0= pK BH + log [B]/[BH+]

5. EXAMPLES
1. Fluorosulphuric acid: (H0= -15.1)
 Is a inorganic compound with chemical formula HSO3F
 Strongest acid commercially available.
 It is a tetrahedral molecule. Colourless liquid, although commercial
samples are yellow.
 It is prepared by reaction of HF and sulfur trioxide.
SO3 + HF HSO3F

6. 2. Carborane: (H0< -18)
 Chemical formula- H(CXB11Y5Z6) (X,Y,Z =H,Akl, F, Cl, Br, CF3)
 These are a class of super acid, some of which are estimated to be
at least one million times stronger than pure sulphuric acid.
 Strongest known Bronsted acid.

7. 3. Fluoroantimonic acid (H0 between -21 and -23)
 Organic compound with chemical formula H2FSbF6.
 It is extremely strong acid.
 Prepared by treating hydrogen fluoride with antimony pentafluoride in a 2:1 ratio
 This results in the formation of fluoronium ion.
2 HF + SbF5 SbF6
- + H2F
+
 The extreme Acidity of fluoroantimonic acid is because of fluoroantimonic ion.

8. 4. Triflic acid (H0 = - 14.9)
 Also known as trifluoromethanesulfonic acid.
 Is a sulfonic acid With chemical formula CF3SO3H.
 It is hygroscopic, colorless, slightly viscous liquid and soluble in polar solvents.
 It is produced industrially by electrochemical fluorination of methane sulfonic
acid.
. CH3SO3H + 4HF CF3SO2F + H2O + 3H2
 CF3SO2F is hydrolyzed.
 It can also be produced by oxidation of trifluoromethylsulfenylchloride.
CF3SCl + 2Cl2 +3H2O CF3SO3H + 5HCl
 It is mainly used in research as a catalyst in esterification.

9. 5. Magic acid (H0 = -19.2)
 It consists a mixture of fluorosulpuric acid and antimony pentafluoride in 1:1
ratio.
 It is conjugate Bronsted- Lewis super acid system developed by George Olah.
 It has been used to stabilize carbonation and hypercoordinated carbonium ions
in liquid medium.
 It can proton weak bases including methane, xenon, halogens and molecular
hydrogen.

10. APPLICATIONS:
 In petrochemist, super acidic media are used as catalysts, especially
for alkylation.
 Typical catalysts are sulfated oxides of titanium or zirconium
specially treated alumina or zeolite.
 Solid acids are alkylation benzene with ethene and propene.

11. Thank you