Beryllium fluoride
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| Beryllium fluoride | |
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| IUPAC name | Berylium fluoride |
| Identifiers | |
| CAS number | 7787-49-7 |
| Properties | |
| Molecular formula | BeF2 |
| Melting point |
552 °C |
| Boiling point |
1327 °C, 1600 K, 2421 °F |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
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Beryllium fluoride is the chemical compound with the formula BeF2. It is the binary beryllium compound with the greatest amount of ionic character (due to the high electronegativity of fluorine), but even so it is not considered ionic by many chemists. This synthetic material is the principal precursor for the manufacture of beryllium metal, which is obtained by reduction of BeF2 at 1300°C:[1]
- BeF2 + Mg → Be + MgF2
Solid crystalline BeF2 has a silica like structure with four coordinate beryllium.[2] Molecular BeF2, is isoelectronic with CO2 and SiO2 and as found in the gas-phase above 1160 °C is a linear molecule with a Be-F distance of 177 pm.[1]. The condensed form adopts a number of different polymeric structures similar to those formed by SiO2 namely α-quartz, β-quartz, crystobalite and tridymite,[3]. The difference between the ambient temperature structures of BeF2 and CO2 reflects the decreased tendency of alkali metals to form multiple bonds. An analogy exists between BeF2 and AlF3: both adopt extended structures at mild temperature.
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[edit] Applications
Beryllium fluoride is used in biochemistry, particularly protein crystallography, since it binds in some of the same ways as phosphate does. ADP and beryllium fluoride together tend to bind to ATP sites and inhibit protein action, making it possible to crystallise proteins in the bound state.[4]
Beryllium fluoride forms a basic constituent of the preferred fluoride salt mixture used in liquid-fluoride nuclear reactors. Typically beryllium fluoride is mixed with lithium fluoride to form a base solvent, into which fluorides of uranium and thorium are introduced. Beryllium fluoride is exceptionally chemically stable and LiF/BeF2 mixtures have low melting points and the best neutronic properties of fluoride salt combinations appropriate for reactor use.
[edit] Safety
All beryllium compounds are highly toxic. Beryllium fluoride is very soluble in water and is thus absorbed easily; as mentioned above, it inhibits ATP uptake. The LD50 in mice is about 100mg/kg by ingestion and 1.8mg/kg by intravenous injection.
[edit] References
- ^ a b Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
- ^ Greenwood, Norman N.; Earnshaw, A. (1997), Chemistry of the Elements (2nd ed.), Oxford: Butterworth-Heinemann, ISBN 0-7506-3365-4
- ^ Reiko Kagawa1, Martin G Montgomery, Kerstin Braig, Andrew G W Leslie and John E Walker (2004). "The structure of bovine F1-ATPase inhibited by ADP and beryllium fluoride". The EMBO Journal 23 (5): 2734–2744. doi:.
[edit] External links
- IARC Monograph "Beryllium and Beryllium Compounds"
- National Pollutant Inventory: Beryllium and compounds fact sheet
- National Pollutant Inventory: Fluoride and compounds fact sheet
- Hazards of Beryllium fluoride
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