Silicon tetrafluoride
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| Silicon tetrafluoride | |
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| General | |
| Systematic name | Silicon tetrafluoride |
| Other names | Tetrafluorosilane Silicon fluoride Fluoro acid air |
| Molecular formula | F4Si |
| SMILES | SiFFFF |
| Molar mass | 104.08 g/mol |
| Appearance | colourless gas ( fuming in moist air) |
| CAS number | [7783-61-1] |
| Properties | |
| Density and phase | 1.66 g/cm3, solid (-95 C) |
| Solubility in water | hydrolysis |
| Other solvents | chlorocarbons, ethers MeCN |
| Melting point | 86 °C |
| Boiling point | sublimes at -95.5 °C at 1 atm |
| Viscosity | ? cP at ?°C |
| Structure | |
| Molecular shape | tetrahedral |
| Dipole moment | 0 D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | toxic, corrosive |
| NFPA 704 | |
| R/S statement | R: 14-26/27/28-31-34 S: 23-26-36/37/39-45 |
| RTECS number | VW2327000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related compounds | SiCl4 SiH4 Dihydrogen hexafluorosilicate |
| Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references |
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Silicon tetrafluoride is the chemical compound with the formula SiF4. This tetrahedral molecule is striking because it has a remarkably narrow liquid range (its boiling point is only 4 °C above its melting point). It was first sythesiszed by John Davy in 1812. [1]
Contents |
[edit] Preparation
SiF4 is a by-product of the production of phosphate fertilizers, resulting from the attack of HF (derived from fluoroapatite protonolysis) on silicates. In the laboratory, the compound is prepared by the heating BaSiF6 >300 °C, whereupon the solid releases volatile SiF4, leaving a residue of BaF2. The required BaSiF6 is prepared by treating aqueous fluorosilicic acid with barium chloride.[2] The corresponding GeF4 is prepared analogously, except that the thermal "cracking" requires 700 °C.[3]
[edit] Uses
This volatile compound finds limited use in microelectronics and organic synthesis.[4]
[edit] Occurence
Vulcanic plumes contain significant amounts of silicon tetrafluoride, the daily production can reach several tonns per day.[5] The silicon tetrafluoride is partly hydrolysed and forms hexafluorosilicic acid.
[edit] References
- ^ John Davy (1812). "An Account of Some Experiments on Different Combinations of Fluoric Acid". Philosophical Transactions of the Royal Society of London 102: 352-369.
- ^ Hoffman, C. J.; Gutowsky, H. S. “Silicon Tetrafluoride” Inorganic Syntheses McGraw-Hill: New York, Volume 4, pages 145-6, 1953.
- ^ Hoffman, C. J.; Gutowsky, H. S. "Germanium Tetrafluoride” Inorganic Syntheses McGraw-Hill: New York, Volume 4, pages 147-8, 1953.
- ^ Shimizu, M. "Silicon(IV) Fluoride" Encyclopedia of Reagents for Organic Synthesis, 2001 John Wiley & Sons. DOI: 10.1002/047084289X.rs011
- ^ T. Mori, M. Sato, Y. Shimoike, K. Notsu (2002). "High SiF4/HF ratio detected in Satsuma-Iwojima volcano's plume by remote FT-IR observation". Earth Planets Space 54: 249-256.
[edit] External links
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