Hexafluoroantimonic acid

Structural formula
General
Surname	Hexafluoroantimonic acid
other names	Fluoro antimonic acid Hexafluoroantimonic acid
Molecular formula	H [SbF 6 ]
Brief description	colorless liquid
External identifiers / databases
CAS number 16950-06-4 EC number 241-023-8 ECHA InfoCard 100.037.279 PubChem 6337100 ChemSpider 21241496 Wikidata Q413278
properties
Molar mass	236.8 g mol −1
Physical state	liquid
density	2.89 g cm −3
Vapor pressure	19 h Pa (18 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 300 + 310 + 330-314-411 P: 260-264-273-280-284-301 + 310
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Hexafluoroantimonic acid , which is counted among the super acids , is one of the strongest acids known . It is a mixture of the very strong Lewis acid antimony (V) fluoride and the medium-strength Brønsted acid hydrogen fluoride in different proportions. Since the acid strength can no longer be measured directly, it is determined using Hammett's acidity function. A mixture in which SbF ₅ and HF are present in a ratio of 1,200 has an H ₀ value of about −21. With larger amounts of SbF ₅ , the H ₀ value decreases further down to the minimum value of −31.3, which is present at a mixing ratio of 1∶1. (Pure sulfuric acid has an H ₀ value of −11.9, making it several trillion times less acidic .)

Due to its strength, hexafluoroantimonic acid, like the similar magic acid , can protonate many substances, especially hydrocarbons . This breaks them down into smaller molecules and is then soluble in many organic solvents.

Reaction of hydrogen fluoride and antimony (V) fluoride to form fluoroantimonic acid

Individual evidence

1. ↑ ^{a b c d e} Fluoroantimonic acid data sheet from Sigma-Aldrich , accessed on April 1, 2011 ( PDF ).
2. ^ E. Riedel: Moderne Anorganische Chemie, de Gruyter, Berlin, 1999 .