Aluminium fluoride

  • Aluminum trifluoride
  • Aluminum (III) trifluoride
  • 7784-18-1
  • 32287-65-3 (monohydrate)
  • 15098-87-0 ( trihydrate )

Colorless hexagonal crystals

Fixed

2.88 g · cm -3

Approximately 1260 ° C

Poorly soluble in water, acids and alkalis

Attention

1 mg · m-3 (measured as the inhalable aerosol fraction)

-1510.4 (13) kJ / mol

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Aluminium fluoride is a salt of aluminum and fluorine with the formula AlF3.

Occurrence

Aluminium fluoride is both anhydrous, as also in several hydrated forms.

Synthesis

The preparation of aluminum fluoride is advantageously carried out by passing hydrogen fluoride on alumina red-hot:

However, the dehydration of the trihydrate is never entirely free of the production of the oxide. To establish, therefore, pure anhydrous aluminum fluoride, then either of the decomposition of Ammoniumhexafluoroaluminat back:

Properties

Aluminum fluoride forms a sparingly soluble in water and organic solvents, colorless triclinic crystalline powder.

Responsiveness

With fluorides of alkali metals complex salts of the compositions M ( AlF4 ), M2 ( AlF5 ) and M3 ( AlF6 ) are formed. Of technical importance is cryolite Na 3 [ AlF6 ].

Use

Aluminum fluoride as a catalyst, as used in dental care for caries prophylaxis. In pure form and as a cryolite is used as a fluxing agent to the melting of light metal, and for the production of aluminum. Thus, the melting temperature of the bauxite may be reduced from about 2000 ° C to 1000 ° C.

CAS registry number PubChem Sublimation (phase transition) Dangerous Substances Directive (67/548/EEC) CRC Handbook of Chemistry and Physics Integrated Authority File
46933
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