Fluorosulfuric acid

Fluorosulfuric acid

Fluorosulfuric acid sample from Sigma-Aldrich.
Names
IUPAC name Sulfurofluoridic acid
Other names Epoxysulfonyl fluoride Fluoridosulfonic acid Fluoridosulphonic acid Fluorinesulfonic acid Fluorinesulphonic acid Fluorosulfonic acid Fluorosulphonic acid Monofluorosulfuric acid Sulfuric fluorohydrin
Properties
Chemical formula	HFSO3
Molar mass	100.06 g/mol
Appearance	Colorless liquid
Odor	Pungent
Density	1.726 g/cm3
Melting point	−87.5 °C (−125.5 °F; 185.7 K)
Boiling point	165.4 °C (329.7 °F; 438.5 K)
Solubility in water	Reacts
Solubility	Reacts with alcohols, amines Soluble in glacial acetic acid, ethyl acetate, nitrobenzene Poorly soluble in alkanes
Vapor pressure	2.47 mmHg at 25 °C
Acidity (pKa)	-10
Hazards
Safety data sheet	Sigma-Aldrich
Flash point	Non-flammable
Related compounds
Related compounds	Sulfuric acid Chlorosulfuric acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Fluorosulfuric acid or sulfurofluoridic acid is one of the strongest commercially available acids, more specifically a superacid. It has the chemical formula HFSO₃.

Properties

Chemical

Fluorosulfuric is one of the strongest known simple Brønsted acids, although carborane-based acids are still stronger. It has an H₀ value of −15.1 compared to −12 for sulfuric acid.

Fluorosulfuric acid reacts with water to release sulfuric acid and hydrofluoric acid.

Physical

Fluorosulfuric acid is a colorless liquid that fumes in air and reacts violently with water.

Availability

Fluorosulfuric acid is sold by chemical suppliers, though it's not easy to acquire.

Preparation

Fluorosulfuric acid is prepared by the reaction of hydrofluoric acid and sulfur trioxide:

HF + SO₃ → HSO₃F

Alternatively, KHF₂ or CaF₂ can be treated with oleum at 250 °C. After the HF is removed by sweeping with an inert gas, HSO₃F can be distilled in a glass apparatus.

Projects

• Make magic acid

Handling

Safety

Fluorosulfuric acid is considered to be highly toxic and corrosive. It hydrolyzes to release HF. Addition of water to this acid is extremely violent, much more that the addition of water to concentrated sulfuric acid.

An antidote for HF, such as calcium gluconate should be present when handling this acid.

Storage

Fluorosulfuric acid should be kept in thick HDPE or PTFE bottles, in a dry place.

Disposal

Strongly dilution with cold water, followed by careful neutralization with a base. Products are sulfates and fluorides, which can be dumped in trash.

References

Relevant Sciencemadness threads

• Strong acids
• best acid/mixtures to readily dissolve organics?