Beryllium fluoride

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Beryllium fluoride
BeF2str.PNG
Beryllium fluoride.JPG
Names
IUPAC name
Beryllium fluoride
Other names
Beryllium difluoride
Difluoroberyllane
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.029.198 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
RTECS number
  • DS2800000
UNII
  • InChI=1S/Be.2FH/h;2*1H/q+2;;/p-2 Yes check.svgY
    Key: JZKFIPKXQBZXMW-UHFFFAOYSA-L Yes check.svgY
  • InChI=1/Be.2FH/h;2*1H/q+2;;/p-2
    Key: JZKFIPKXQBZXMW-NUQVWONBAD
  • solid ionic form:[Be+2].[F-].[F-]
  • solid covalent form:F[Be]F
  • gas form:[F+]=[Be-2]=[F+]
Properties
BeF2
Molar mass 47.01 g/mol
hygroscopic
Appearancecolorless, glassy lumps
Density 1.986 g/cm3
Melting point 554 °C (1,029 °F; 827 K) [1]
Boiling point 1,169 °C (2,136 °F; 1,442 K) [2]
very soluble
Solubility sparingly soluble in alcohol
Structure
Trigonal, α-quartz
P3121 (No. 152), Pearson symbol hP9 [3]
a = 473.29 pm, c = 517.88 pm
Linear
Thermochemistry
1.102 J/K or 59 J/mol K
Std molar
entropy (S⦵298)
45 J/mol K
-1028.2 kJ/g or -1010 kJ/mol
-941 kJ/mol
Hazards [4]
GHS labelling:
GHS-pictogram-acid.svg GHS-pictogram-skull.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H301, H305, H311, H314, H315, H319, H330, H335, H372, H411
P201, P202, P260, P264, P270, P271, P273, P280, P281, P284, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P308+P313, P310, P312, P314, P320, P321, P322, P330, P361, P363, P391, P403+P233, P405, P501
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
90 mg/kg (oral, rat)
100 mg/kg (oral, mouse) [5]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 0.002 mg/m3
C 0.005 mg/m3 (30 minutes), with a maximum peak of 0.025 mg/m3 (as Be) [6]
REL (Recommended)
Ca C 0.0005 mg/m3 (as Be) [6]
IDLH (Immediate danger)
Ca [4 mg/m3 (as Be)] [6]
Safety data sheet (SDS) InChem MSDS
Related compounds
Other anions
Beryllium chloride
Beryllium bromide
Beryllium iodide
Other cations
Magnesium fluoride
Calcium fluoride
Strontium fluoride
Barium fluoride
Radium fluoride
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Beryllium fluoride is the inorganic compound with the formula Be F 2. This white solid is the principal precursor for the manufacture of beryllium metal. Its structure resembles that of quartz, but BeF2 is highly soluble in water.

Contents

Properties

Beryllium fluoride has distinctive optical properties. In the form of fluoroberyllate glass, it has the lowest refractive index for a solid at room temperature of 1.275. Its dispersive power is the lowest for a solid at 0.0093, and the nonlinear coefficient is also the lowest at 2 × 10−14.

Structure and bonding

Structure of gaseous BeF2. Beryllium-fluoride-3D-vdW.png
Structure of gaseous BeF2.

The structure of solid BeF2 resembles that of cristobalite. Be2+ centers are four coordinate and tetrahedral and the fluoride centers are two-coordinate. [7] The Be-F bond lengths are about 1.54 Å. [8] Analogous to SiO2, BeF2 can also adopt a number of related structures. An analogy also exists between BeF2 and AlF3: both adopt extended structures at mild temperature.

Gaseous and liquid BeF2

Gaseous beryllium fluoride adopts a linear structure, with a Be-F distance of 143 pm. [9] BeF2 reaches a vapor pressure of 10 Pa at 686 °C, 100 Pa at 767 °C, 1 kPa at 869 °C, 10 kPa at 999 °C, and 100 kPa at 1172 °C. [10] Molecular BeF2 in the gaseous state is isoelectronic to carbon dioxide.

As a liquid, beryllium fluoride has a tetrahedral structure. The density of liquid BeF2 decreases near its freezing point, as Be2+ and F− ions begin to coordinate more strongly with one another, leading to the expansion of voids between formula units. [11]

Production

The processing of beryllium ores generates impure Be(OH)2. This material reacts with ammonium bifluoride to give ammonium tetrafluoroberyllate:

Be(OH)2 + 2 (NH4)HF2 → (NH4)2BeF4 + 2 H2O

Tetrafluoroberyllate is a robust ion, which allows its purification by precipitation of various impurities as their hydroxides. Heating purified (NH4)2BeF4 gives the desired product:

(NH4)2BeF4 → 2 NH3 + 2 HF + BeF2

In general the reactivity of BeF2 ions with fluoride are quite analogous to the reactions of SiO2 with oxides. [12]

Applications

Reduction of BeF2 at 1300 °C with magnesium in a graphite crucible provides the most practical route to metallic beryllium: [9]

BeF2 + Mg → Be + MgF2

The Beryllium chloride is not a useful precursor because of its volatility. [ citation needed ]

Niche uses

Beryllium fluoride is used in biochemistry, particularly protein crystallography as a mimic of phosphate. Thus, 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. [13] [14]

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 (FLiBe), into which fluorides of uranium and thorium are introduced. Beryllium fluoride is exceptionally chemically stable, and LiF/BeF2 mixtures (FLiBe) have low melting points (360–459 °C) and the best neutronic properties of fluoride salt combinations appropriate for reactor use. MSRE used two different mixtures in the two cooling circuits.

Safety

Beryllium compounds are highly toxic. The increased toxicity of beryllium in the presence of fluoride has been noted as early as 1949. [15] The LD50 in mice is about 100 mg/kg by ingestion and 1.8 mg/kg by intravenous injection.

Related Research Articles

<span class="mw-page-title-main">Hydrofluoric acid</span> Solution of hydrogen fluoride in water

Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. A common concentration is 49% (48-52%) but there are also stronger solutions and pure HF has a boiling point near room temperature. It is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidepressant medication fluoxetine (Prozac) and the material PTFE (Teflon). Elemental fluorine is produced from it. It is commonly used to etch glass and silicon wafers.

<span class="mw-page-title-main">Tungsten hexafluoride</span> Chemical compound

Tungsten(VI) fluoride, also known as tungsten hexafluoride, is an inorganic compound with the formula WF6. It is a toxic, corrosive, colorless gas, with a density of about 13 kg/m3 (22 lb/cu yd). It is the only known gaseous transition metal compound and the densest known gas under standard ambient temperature and pressure. WF6 is commonly used by the semiconductor industry to form tungsten films, through the process of chemical vapor deposition. This layer is used in a low-resistivity metallic "interconnect". It is one of seventeen known binary hexafluorides.

<span class="mw-page-title-main">Magnesium fluoride</span> Chemical compound of magnesium and fluorine

Magnesium fluoride is an ionically bonded inorganic compound with the formula MgF2. The compound is a colorless to white crystalline salt and is transparent over a wide range of wavelengths, with commercial uses in optics that are also used in space telescopes. It occurs naturally as the rare mineral sellaite.

<span class="mw-page-title-main">Lithium fluoride</span> Chemical compound

Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid that transitions to white with decreasing crystal size. Its structure is analogous to that of sodium chloride, but it is much less soluble in water. It is mainly used as a component of molten salts. Partly because Li and F are both light elements, and partly because F2 is highly reactive, formation of LiF from the elements releases one of the highest energies per mass of reactants, second only to that of BeO.

<span class="mw-page-title-main">Copper(II) fluoride</span> Chemical compound

Copper(II) fluoride is an inorganic compound with the chemical formula CuF2. The anhydrous form is a white, ionic, crystalline, hygroscopic salt with a distorted rutile-type crystal structure, similar to other fluorides of chemical formulae MF2 (where M is a metal). The dihydrate, CuF2·2H2O, is blue in colour.

Antimony pentafluoride is the inorganic compound with the formula SbF5. This colourless, viscous liquid is a strong Lewis acid and a component of the superacid fluoroantimonic acid, formed upon mixing liquid HF with liquid SbF5 in 1:1 ratio. It is notable for its strong Lewis acidity and the ability to react with almost all known compounds.

<span class="mw-page-title-main">Hydrogen fluoride</span> Chemical compound

Hydrogen fluoride (fluorane) is an inorganic compound with chemical formula HF. It is a very poisonous, colorless gas or liquid that dissolves in water to yield an aqueous solution termed hydrofluoric acid. It is the principal industrial source of fluorine, often in the form of hydrofluoric acid, and is an important feedstock in the preparation of many important compounds including pharmaceuticals and polymers, e.g. polytetrafluoroethylene (PTFE). HF is also widely used in the petrochemical industry as a component of superacids. Due to strong and extensive hydrogen bonding, it boils at near room temperature, much higher than other hydrogen halides.

<span class="mw-page-title-main">Xenon difluoride</span> Chemical compound

Xenon difluoride is a powerful fluorinating agent with the chemical formula XeF
2, and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with water vapor, but is otherwise stable in storage. Xenon difluoride is a dense, colourless crystalline solid.

<span class="mw-page-title-main">Aluminium fluoride</span> Chemical compound

Aluminium fluoride is an inorganic compound with the formula AlF3. It forms hydrates AlF3·xH2O. Anhydrous AlF3 and its hydrates are all colorless solids. Anhydrous AlF3 is used in the production of aluminium. Several occur as minerals.

<span class="mw-page-title-main">Zirconium tetrafluoride</span> Chemical compound

Zirconium(IV) fluoride describes members of a family inorganic compounds with the formula (ZrF4(H2O)x. All are colorless, diamagnetic solids. Anhydrous Zirconium(IV) fluoride' is a component of ZBLAN fluoride glass.

<span class="mw-page-title-main">Selenium tetrafluoride</span> Chemical compound

Selenium tetrafluoride (SeF4) is an inorganic compound. It is a colourless liquid that reacts readily with water. It can be used as a fluorinating reagent in organic syntheses (fluorination of alcohols, carboxylic acids or carbonyl compounds) and has advantages over sulfur tetrafluoride in that milder conditions can be employed and it is a liquid rather than a gas.

<span class="mw-page-title-main">Krypton difluoride</span> Chemical compound

Krypton difluoride, KrF2 is a chemical compound of krypton and fluorine. It was the first compound of krypton discovered. It is a volatile, colourless solid at room temperature. The structure of the KrF2 molecule is linear, with Kr−F distances of 188.9 pm. It reacts with strong Lewis acids to form salts of the KrF+ and Kr
2F+
3 cations.

<span class="mw-page-title-main">Manganese(IV) fluoride</span> Chemical compound

Manganese tetrafluoride, MnF4, is the highest fluoride of manganese. It is a powerful oxidizing agent and is used as a means of purifying elemental fluorine.

<span class="mw-page-title-main">Beryllium chloride</span> Chemical compound

Beryllium chloride is an inorganic compound with the formula BeCl2. It is a colourless, hygroscopic solid that dissolves well in many polar solvents. Its properties are similar to those of aluminium chloride, due to beryllium's diagonal relationship with aluminium.

<span class="mw-page-title-main">Beryllium iodide</span> Chemical compound

Beryllium iodide is an inorganic compound with the chemical formula BeI2. It is a hygroscopic white solid. The Be2+ cation, which is relevant to salt-like BeI2, is characterized by the highest known charge density (Z/r = 6.45), making it one of the hardest cations and a very strong Lewis acid.

Arsenic trifluoride is a chemical compound of arsenic and fluorine with the chemical formula AsF3. It is a colorless liquid which reacts readily with water.

A hexafluoride is a chemical compound with the general formula QXnF6, QXnF6m−, or QXnF6m+. Many molecules fit this formula. An important hexafluoride is hexafluorosilicic acid (H2SiF6), which is a byproduct of the mining of phosphate rock. In the nuclear industry, uranium hexafluoride (UF6) is an important intermediate in the purification of this element.

<span class="mw-page-title-main">FLiBe</span> Chemical compound

FLiBe is the name of a molten salt made from a mixture of lithium fluoride (LiF) and beryllium fluoride. It is both a nuclear reactor coolant and solvent for fertile or fissile material. It served both purposes in the Molten-Salt Reactor Experiment (MSRE) at the Oak Ridge National Laboratory.

<span class="mw-page-title-main">Chromyl fluoride</span> Chemical compound

Chromyl fluoride is an inorganic compound with the formula CrO2F2. It is a violet-red colored crystalline solid that melts to an orange-red liquid.

<span class="mw-page-title-main">Tetrafluoroberyllate</span> Anion

Tetrafluoroberyllate or orthofluoroberyllate is an anion with the chemical formula [BeF4]2−. It contains beryllium and fluorine. This fluoroanion has a tetrahedral shape, with the four fluorine atoms surrounding a central beryllium atom. It has the same size, charge, and outer electron structure as sulfate SO2−4. Therefore, many compounds that contain sulfate have equivalents with tetrafluoroberyllate. Examples of these are the langbeinites, and Tutton's salts.

References

  1. ↑ "Beryllium Fluoride". American Elements. Retrieved 10 July 2023.
  2. ↑ Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN   0-8493-0487-3.
  3. ↑ Wright, Albert F.; Fitch, Andrew N.; Wright, Adrian C. (1988). "The preparation and structure of the α- and β-quartz polymorphs of beryllium fluoride". Journal of Solid State Chemistry. 73 (2): 298. Bibcode:1988JSSCh..73..298W. doi:10.1016/0022-4596(88)90113-2.
  4. ↑ "Beryllium Difluoride". PubChem. National Institute of Health. Retrieved October 13, 2017.
  5. ↑ "Beryllium compounds (as Be)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  6. 1 2 3 NIOSH Pocket Guide to Chemical Hazards. "#0054". National Institute for Occupational Safety and Health (NIOSH).
  7. ↑ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN   0-19-855370-6
  8. ↑ Pallavi Ghalsasi, Prasanna S. Ghalsasi, "Single Crystal X-Ray Structure of BeF2: α-Quartz" Inorg. Chem., 2011, 50 (1), pp 86–89. doi : 10.1021/ic101248g
  9. 1 2 Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN   0-12-352651-5.
  10. ↑ Vapor pressure, physics.nyu.edu, p. 6-63, from Ohe, S. (1976) Computer Aided Data Book of Vapor Pressure, Data Book Publishing Co., Tokyo.
  11. ↑ Agarwal, M.; Chakravarty C (2007). "Waterlike Structural and Excess Entropy Anomalies in Liquid Beryllium Fluoride". J. Phys. Chem. B. 111 (46): 13294–300. doi:10.1021/jp0753272. PMID   17963376.
  12. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN   978-0-08-037941-8.
  13. ↑ Reiko Kagawa; Martin G. Montgomery; Kerstin Braig; Andrew G. W. Leslie; John E. Walker (2004). "The structure of bovine F1-ATPase inhibited by ADP and beryllium fluoride". The EMBO Journal. 23 (5): 2734–2744. doi:10.1038/sj.emboj.7600293. PMC   514953 . PMID   15229653.
  14. ↑ Bigay J.; Deterre P.; Pfister C.; Chabre M. (1987). "Fluoride complexes of aluminium or beryllium act on G-proteins as reversibly bound analogues of the gamma phosphate of GTP". The EMBO Journal. 6 (10): 2907–2913. doi:10.1002/j.1460-2075.1987.tb02594.x. PMC   553725 . PMID   2826123.
  15. ↑ Fluoride in Drinking Water: A Scientific Review of EPA's Standards. The National Academies Press. 2006. pp. 51–52. doi:10.17226/11571. ISBN   978-0-309-10128-8.