Hydrogen fluoride-fluorosulfuric acid

Hydrogen Fluoride-Fluorosulfuric Acid. Fluorosulfuric acid containing up to 5% of HF acting as a protic coacid was found to be very efficient for isomerization of ra-butane to isobutane at room temperature, whereas pure HSO3F did not show this activity. Moreover, at higher HF concentration the activity diminishes substantially.68... 

Several cyclopropylmethyl cations have been prepared by treating cyclopropyl ketones with super acids at low temperature. The hydrogen fluoride/antimony(V) fluoride mixture has been most frequently employed, but hydrogen chloride in antimony(V) chloride and antimony(V) fluoride/fluorosulfuric acid/fluorosulfuric chloride have also been used. The counterion is, therefore, hexahaloantimonate. Yields were generally not reported an exception was the isolation of tricyclopropylmethylium hexafluoroantimonate in 86% yield on reaction of tricyclopropylmethanol with antimony(V) fluoride. " ... 

Perchloric acid (HCIO4 Ho —13.0), fluorosulfuric acid (HSO3F Ho — 15.1), and trifluoromethanesulfonic acid (CF3SO3H Ho —14.1) are considered to be superacids, as is truly anhydrous hydrogen fluoride. Complexing with Lewis acidic metal fluorides of higher valence, such as antimony, tantalum, or niobium pentafluoride, greatly enhances the acidity of all these acids. 

Fluorosulfuric acid is stable to heat up to decomposition at about 900°C (13), where vapor-phase dissociation into hydrogen fluoride and sulfur trioxide probably occurs. Reviews of the chemistry and properties of fluorosulfuric acid have been pubUshed (14—16). 

The same indicators have been used to compare the relative acidity of the three most used superacids. As shown on Figure 1.7, the half-protonation of indicator 3 necessitates 40, 25, and 8mol% SbF5, respectively, in triflic acid, fluorosulfuric acid, and hydrogen fluoride systems. These results show the supremacy of the HF-SbF5 system in which small concentrations of SbF5 induce a dramatic increase in acidity (see also Section 2.2.2.7). 

Concentrating initially only on the physical and chemical nature of the four superacids in common use, it can be shown that, for most synthetic purposes, the fluorine-containing superacids, fluorosulfuric acid (HS03F), trifluoromethyl-sulfuric or triflic acid (CF3S03H) and hydrogen fluoride (HF) offer far more... 

My research has been mainly in superacids, sulfuric acid, fluorosulfuric acid and hydrogen fluoride, which led me naturally into fluorine chemistry. I didn t do a lot more on VSEPR except for trying to promote it. I was excited by the discovery of the noble-gas compounds, and it was an obvious opportunity to show that it was easy to use VSEPR to predict their structures. At one of the early conferences on noble-gas chemistry, Larry Bartell asked me to predict the structure of XeF. I believe he had already determined the structure by electron diffraction but not yet published it. I told him that it could not be octahedral, which the MO theorists believed they had proved, but was probably a distorted monocapped octahedron, which turned out to be correct. Since then, he has been a great fan of VSEPR and has done much to promote it as a useful theory. 

Hydrogen fluoride (UF) Hypofluorous acid (HOF) Fluorosulfuric acid (HSO F) Fluorosilane (SiH F)... 

Acids, strong, mineral Fluorosulfuric acid. Hydrobromic acid. Hydrochloric acid. Hydrogen fluoride. 

FLUOROSULFURIC ACID (7789-21-1) Reacts violently with moisture (including moisture in air), generating hydrogen fluoride and sulfuric acid. Solution is a strong acid. Aqueous solution is incompatible with sulfuric acid, alkalis, ammonia, aliphatic amines, alka-nolamines, alkylene oxides, amides, epichlorohydrin, organic anhydrides, isocyanates, vinyl acetate. Increases the explosive sensitivity of nitromethane. Attacks metals, especially in the presence of moisture, liberating flammable hydrogen gas. 

Anhydrous hydrogen fluoride and fluorosulfuric acid were found as improved solvents for the nitration of methane with nitronium salts. In these strong acid solvents even under the mild reaction conditions (room ten jerature) at least tenfold increased yields ( %) could be obtained. As no protolytic reactions of methane take place in HF under the reaction conditions, side reactions are not observed. This is not the case in the nitration of isobutane in HF solution, where 90 of the nitroalkanes obtained consisted of l-nitro-2-methylpropane. Since only traces of this iscmer were found in nitronium salt nitration in aprotic CH2Cl2-sulfolane solution, the formation of l-nitro-2-methylpropane must be considered due to formation of isobutylene (either frcm isobutane itself in HF containing PFc or more probably frcm the protolytic cleavage of 2-nltro-2-meuhylpropane). 

FSO3H Fluorosulfuric acid, 7 127 FaAg Silver(II) fluoride, 3 176 F2CO Carbonyl fluoride, 6 155 FsCa Calcium fluoride, 4 137 FaHg Mercury (II) fluoride, 4 136 F2KH Potassium hydrogen fluoride, 1 140... 

Related Reagents. Fluorosulfuric Acid-Antimony(V) Fluoride Hydrogen Fluoride-Antimony(V) Fluoride Methyl Fluoride-Antimony(V) Fluoride. 

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