Fluorosulfonic acid

Structural formula
General
Surname	Fluorosulfonic acid
other names	Fluorosulfuric acid; Sulfuric acid fluoride; Sulfuric acid monofluoride;
Molecular formula	HSO 3 F
Brief description	colorless, pungent smelling liquid
External identifiers / databases
EC number	232-149-4
ECHA InfoCard	100.029.227
PubChem	24603
Wikidata	Q411017
properties
Molar mass	100.06 g mol −1
Physical state	liquid
density	1.73 g cm −3 (15 ° C)
Melting point	−89 ° C
boiling point	163 ° C
Vapor pressure	15 h Pa (50 ° C)
solubility	Decomposes in water
safety instructions
H and P phrases	H: 332-314
	P: 280-305 + 351 + 338-310
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Fluorosulfonic acid , also known as fluorosulfuric acid , is a chemical compound with the empirical formula FSO ₃ H. The liquid, which is colorless at room temperature, is one of the strongest commercially available acids . The tetrahedrally constructed molecule can also be the structural formula HOSO ₂ will be described in F to the affinity for sulfuric acid (H ₂ SO ₄ ) stress.

Extraction and presentation

Fluorosulfonic acid is produced by the reaction of hydrogen fluoride and sulfur trioxide or chlorosulfonic acid :

{\ displaystyle \ mathrm {HF + SO_ {3} \ longrightarrow HSO_ {3} F}}

{\ displaystyle \ mathrm {HF + HSO_ {3} Cl \ longrightarrow HSO_ {3} F + HCl}}

Alternatively, KHF ₂ or CaF ₂ can be treated with disulfuric acid at 250 ° C. Once freed from hydrofluoric acid by flushing with an inert gas , HSO ₃ F can be distilled in a glass vessel.

It is also possible to produce it by reacting potassium hydrogen difluoride with sulfuric acid and sulfur trioxide.

{\ displaystyle \ mathrm {2 \ KHF_ {2} +4 \ SO_ {3} + H_ {2} SO_ {4} \ longrightarrow HSO_ {3} F + K_ {2} SO_ {4}}}

Chemical properties

Fluorosulfonic acid is soluble in polar organic solvents (e.g. nitrobenzene , diethyl ether , acetic acid and ethyl acetate ), but poorly soluble in non-polar solvents such as alkanes . Due to its great strength, it dissolves almost all organic compounds that are only weak proton acceptors . FSO ₃ H slowly hydrolyzes to hydrofluoric acid and sulfuric acid. At room temperature it does not react with S, C, Se, Te, Pb, Ag, Cu, Zn, Fe, Cr, Mn, but it does react with tin. It reacts explosively with water. It is thermally stable up to 900 ° C. The similar trifluoromethanesulfonic acid CF ₃ SO ₃ H is a similarly strong acid, but hydrolytically stable.

FSO ₃ H is one of the strongest simple Brønsted acids known , although recent work on carborane acids has resulted in stronger acids. It has an H ₀ value of −15 compared to −12 for sulfuric acid. The combination of FSO ₃ H and the Lewis acid antimony (V) fluoride results in “ magic acid ”, which is an even stronger acid. These acids are called “ super acids ” (acids that are stronger than 100% sulfuric acid).

use

Fluorosulfonic acid is used for the chemical synthesis of fluorine compounds, in the glass industry and as a catalyst for chemical synthesis. It isomerizes alkanes and catalyzes the alkylation of hydrocarbons with alkenes . It can also be used as a fluorinating agent and, in a mixture with antimony pentafluoride, as a particularly strong protonating agent ( magic acid ).

safety instructions

Fluorosulfonic acid is highly corrosive and, in the presence of moisture or water, strongly attacks glass and other silicon-containing materials as well as most metals. It hydrolyzes with the release of hydrofluoric acid. Adding water to HSO ₃ F is just as dangerous as adding water to concentrated sulfuric acid.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Entry on fluorosulphonic acid in the GESTIS substance database of the IFA , accessed on September 4, 2016(JavaScript required) .
↑ Entry on Fluorosulphuric acid in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ ^a ^b Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 193.

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Entry on fluorosulphonic acid in the GESTIS substance database of the IFA , accessed on September 4, 2016(JavaScript required) .

[CLP_100.029.227-2] Entry on Fluorosulphuric acid in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[brauer-3] Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 193.