Hexafluorosilicic acid
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| Dihydrogen hexafluorosilicate | |
|---|---|
| Image:Hexafluorosilicic acid.png | |
| General | |
| Systematic name | Dihydrogen hexafluorosilicate |
| Other names | Hexafluorosilicic acid fluorosilicic acid |
| Molecular formula | H2F6Si |
| Molar mass | 144.0922 g/mol |
| Appearance | colourless solution |
| CAS number | [] |
| Properties | |
| Density and phase | 1.22 g/cm3 25% aqueous soln |
| Other solvents | acetonitrile tertiary butanol |
| Acidity (pKa) | ? |
| Structure | |
| Molecular shape | Octahedral SiF62- |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | Toxic, corrosive. |
| NFPA 704 | |
| Flash point | Non-flammable. |
| R/S statement | R: R20, R21, R22, R34, R41 S: S26, S27 |
| RTECS number | VV8225000 |
| Supplementary data page | |
| Related compounds | |
| Related compounds | HF HPF6 HBF4 |
| 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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Hexafluorosilicic acid is the chemical compound with the formula H2SiF6. The species is encountered only as an aqueous solution. Pure H2SiF6 is unstable with respect to loss of HF and SiF4.
H2SiF6 is a by-product from the reaction of fluoroapatite with sulfuric acid, which produces HF, which in turn reacts with silicate minerals:
- SiO2 + 6 HF → H2SiF6 + 2 H2O
Aqueous solutions of H2SiF6 contain the hexafluorosilicate anion, SiF62-. In this octahedral anion, the Si-F bond distances are 1.71 A.[1]
Contents |
[edit] Uses
H2SiF6 is commonly used for water fluoridation in the United States.
H2SiF6 is a reagent in organic synthesis for cleaving Si-O bonds of silyl ethers. It is more reactive for this purpose than HF. It reacts faster with t-butyldimethysilyl (TBDMS) ethers than a triisopropylsilyl (TIPS) ethers.[2]
[edit] Safety
Precautions associated with hydrofluoric acid apply also to hexafluorosilicic acid.
[edit] References
- ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ Pilcher, A. S.; DeShong, P. “Fluorosilicic Acid” in Encyclopedia of Reagents for Organic Synthesis, Copyright © 2001 John Wiley & Sons. DOI: 10.1002/047084289X.rf013
[edit] External links
- Dihydrogen hexafluorosilicate MSDS sheet.
- Hydrofluorosilic acid MSDS sheet
- Links to external chemical sources
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