Aluminium fluoride
| Aluminium fluoride | |
|---|---|
| |
| |
| Other names | Aluminium(III) fluoride Aluminum trifluoride |
| Identifiers | |
| InChI | InChI=1/Al.3FH/h;3*1H/q+3;;;/p-3 |
| InChIKey | KLZUFWVZNOTSEM-DFZHHIFOAC |
| Standard InChI | InChI=1S/Al.3FH/h;3*1H/q+3;;;/p-3 |
| Standard InChIKey | KLZUFWVZNOTSEM-UHFFFAOYSA-K |
| CAS number | [], 32287-65-3 (monohydrate) 15098-87-0 (trihydrate) |
| EC number | |
| RTECS | BD0725000 |
| ChemSpider | |
| PubChem | |
| Properties[1] | |
| Chemical formula | AlF3 |
| Molar mass | 83.977 g/mol (anhydrous) 101.022 g/mol (monohydrate) 138.023 g/mol (trihydrate) |
| Appearance | white, crystalline solid, odorless |
| Density | 2.882 g/cm3 (anhydrous) 2.17 g/cm3 (monohydrate) 1.914 g/cm3 (trihydrate) |
| Boiling point |
1291 °C subl. |
| Solubility in water | 0.559 g/100 ml (25 °C) 1.72 g/100 ml (100 °C) |
| Structure | |
| Crystal structure | Rhombohedral, hR24 |
| Space group | R-3c, No. 167 |
| Hazards[2] | |
| EU classification | Harmful (Xn) |
| R-phrases | Template:R22, Template:R36/37/38 |
| S-phrases | Template:S26 |
| NFPA 704 |
 |
| Template:Tick(what is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Aluminium fluoride is the inorganic compound with the formula AlF3. This colourless solid can be prepared synthetically but also occurs in nature. It is produced and used on a large scale as a component in the production of aluminium.
Production and occurrence
The majority of aluminium fluoride is produced by heating hexafluorosilicic acid with alumina under nitrogen:[3]
- H2SiF6 + Al2O3 → 2 AlF3 + SiO2 + H2O
In the laboratory, AlF3 can be prepared by treating aluminium hydroxide or aluminium metal with hydrofluoric acid. Aluminium fluoride is found in nature as the rare minerals fluellite (monohydrate) and rosenbergite (trihydrate).
Structure
Its structure resembles that of rhenium trioxide, ReO3, consisting of distorted AlF6 octahedra. Each fluoride is connected to two Al centers. The structure helps explain why AlF3 is refractory, in strong contrast to the other halides of aluminium.[4] AlCl3, AlBr3, and AlI3 are dimeric in the liquid and evaporate as dimers as well. In the gas phase, at ca. 1000 °C, aluminium fluoride exists as trigonal molecules of D3h symmetry group. The Al-F bond lengths are 163 pm.
Applications
Aluminium fluoride is an important additive that allows the production of aluminium by electrolysis. It lowers the melting point of the alumina feed and, together with cryolite, increases the conductivity of the solution.[3] Together with zirconium fluoride, aluminium fluoride is the basis of fluoroaluminate glasses.
It is also used in ceramics, as flux in metallurgy and to inhibit fermentation, and as an evaporation material and sputtering target for preparation of low index films.
References
- ↑ CRC Handbook of Chemistry and Physics, 62nd ed.; Weast, Robert C., Ed.; CRC Press: Boca Raton, FL, 1981; p B-73. ISBN 0-8493-0462-8.
- ↑ BGIA GESTIS (English version)
- ↑ 3.0 3.1 Aigueperse, J.; Mollard, P.; Devilliers, D.; Chemla, M.; Faron, R.; Romano, R.; Cuer, J. P. Fluorine Compounds, Inorganic. In Ullmann’s Encyclopedia of Industrial Chemistry, 5th ed.; Wiley-VCH: Weinheim, 2005.
- ↑ Holleman, A. F.; Wiberg, E. Inorganic Chemistry; Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
External links
- International Chemical Safety Card 1324
- European Union Risk Assessment Report (March 2008)
- NIOSH Pocket Guide to Chemical Hazards 0024
- IPCS Environmental Health Criteria 194: Aluminium
- MSDS
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