Aluminium fluoride refers to inorganic compounds with the formula AlF3·xH2O. They are all colorless solids. Anhydrous AlF3 is used in the production of aluminium metal. Several occur as minerals.
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||83.977 g/mol (anhydrous) |
101.992 g/mol (monohydrate)
|Appearance||white, crystalline solid|
|Density||3.10 g/cm3 (anhydrous) |
2.17 g/cm3 (monohydrate)
1.914 g/cm3 (trihydrate)
|Melting point||1,290 °C (2,350 °F; 1,560 K) (anhydrous) (sublimes)|
|5.6 g/L (0 °C) |
6.7 g/L (20 °C)
17.2 g/L (100 °C)
Refractive index (nD)
|1.3767 (visible range)|
|R3c, No. 167|
a = 0.49254 nm, c = 1.24477 nm
Lattice volume (V)
Formula units (Z)
Heat capacity (C)
Std enthalpy of
Gibbs free energy (ΔfG˚)
|H301, H302, H314, H315, H319, H335, H361, H372|
|P260, P261, P264, P270, P271, P280, P301+P310, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P330, P332+P313, P337+P313, P362, P363, P403+P233, P405, P501|
|NFPA 704 (fire diamond)|
|NIOSH (US health exposure limits):|
IDLH (Immediate danger)
|Safety data sheet (SDS)||InChem MSDS|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
(what is ?)
Aside from anhydrous AlF3, several hydrates are known. With the formula AlF3·xH2O, these compounds include monohydrate (x = 1), two polymorphs of the trihydrate (x = 3), a hexahydrate (x = 6), and a nonahydrate (x = 9).
Alternatively, it is manufactured by thermal decomposition of ammonium hexafluoroaluminate. For small scale laboratory preparations, AlF3 can also be prepared by treating aluminium hydroxide or aluminium metal with hydrogen fluoride.
Aluminium fluoride trihydrate is found in nature as the rare mineral rosenbergite.
According to X-ray crystallography, anhydrous AlF3 adopts the rhenium trioxide motif, featuring distorted AlF6 octahedra. Each fluoride is connected to two Al centers. Because of its three-dimensional polymeric structure, AlF3 has a high melting point. The other trihalides of aluminium in the solid state differ, AlCl3 has a layer structure and AlBr3 and AlI3, are molecular dimers.[page needed] Also they have low melting points and evaporate readily to give dimers.[page needed] In the gas phase aluminium fluoride exists as trigonal molecules of D3h symmetry. The Al–F bond lengths of this gaseous molecule are 163 pm.
Aluminium fluoride is an important additive for the production of aluminium by electrolysis. Together with cryolite, it lowers the melting point to below 1000 °C and increases the conductivity of the solution. It is into this molten salt that aluminium oxide is dissolved and then electrolyzed to give bulk Al metal.
Aluminum fluoride complexes are used to study the mechanistic aspects of phosphoryl transfer reactions in biology, which are of fundamental importance to cells, as phosphoric acid anhydrides such as ATP and GTP control most of the reactions involved in metabolism, growth and differentiation. The observation that aluminum fluoride can bind to and activate heterotrimeric G proteins has proven to be useful for the study of G protein activation in vivo, for the elucidation of three-dimensional structures of several GTPases, and for understanding the biochemical mechanism of GTP hydrolysis, including the role of GTPase-activating proteins.
It is also used to inhibit fermentation.
Like magnesium fluoride it is used as a low-index optical thin film, particularly when far UV transparency is required. Its deposition by physical vapor deposition, particularly by evaporation, is favorable.
The reported oral animal lethal dose (LD50) of aluminum fluoride is 0.1 g/kg. Repeated or prolonged inhalation exposure may cause asthma, and may have effects on the bone and nervous system, resulting in bone alterations (fluorosis), and nervous system impairment.
Many of the neurotoxic effects of fluoride are due to the formation of aluminum fluoride complexes, which mimic the chemical structure of a phosphate and influence the activity of ATP phosphohydrolases and phospholipase D. Only micromolar concentrations of aluminum are needed to form aluminum fluoride.
Human exposure to aluminum fluoride can occur in an industrial setting, such as emissions from aluminum reduction processes, or when a person ingests both a fluoride source (e.g., fluoride in drinking water or residue of fluoride-based pesticides) and an aluminum source; sources of human exposure to aluminum include drinking water, tea, food residues, infant formula, aluminum-containing antacids or medications, deodorants, cosmetics, and glassware. Fluoridation chemicals may also contain aluminum fluoride. Data on the potential neurotoxic effects of chronic exposure to the aluminum species existing in water are limited.
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