Teflic acid
Teflic acid is the chemical compound with the formula HOTeF5. This strong acid is related to orthotelluric acid, Te(OH)6. Teflic acid has a slightly distorted octahedral geometry.
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| Names | |||
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| IUPAC name
Pentafluoroorthotelluric acid | |||
| Other names
Teflic acid | |||
| Identifiers | |||
3D model (JSmol) |
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| ChemSpider | |||
| ECHA InfoCard | 100.161.534 | ||
CompTox Dashboard (EPA) |
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| Properties | |||
| HF5OTe | |||
| Molar mass | 239.6 | ||
| Appearance | colorless solid | ||
| Melting point | 39.1 °C (102.4 °F; 312.2 K) | ||
| Boiling point | 59.7 °C (139.5 °F; 332.8 K) | ||
| Hazards | |||
| Main hazards | corrosive, toxic | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
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| Infobox references | |||
Preparation
Teflic acid was accidentally discovered by Engelbrecht and Sladky. Their synthesis did not yield the anticipated telluryl fluoride TeO2F2, but a mixture of volatile telluric compounds, i.a. HOTeF5:[1]
- BaTeO4 + 10HOSO2F → HOTeF5 (25 %)
Teflic acid can also be prepared from fluorosulfonic acid and barium tellurate:[2]
- 5HOSO2F + BaO2Te(OH)4 → HOTeF5 + 4 H2SO4 + BaSO4
It is also the first hydrolysis product of tellurium hexafluoride:
- TeF6 + H2O → HOTeF5 + HF
Teflates
The conjugate base of teflic acid is called the teflate anion, F5TeO− (not to be confused with triflate). Many teflates are known, examples being B(OTeF5)3 and the acid anhydride O(TeF5)2. Pyrolysis of the boron compound gives the dimer (TeF4O)2[2]
- 2 B(OTeF5)3 → 2 B(OTeF5)2F + (OTeF4)2
The teflate anion is known to resist oxidation. This property has allowed the preparation several highly unusual species such as the hexateflates M(OTeF5)6− (M = As, Sb, Bi). Xenon forms the cation Xe(OTeF5)+.[3]
References
- Engelbrecht, A.; Sladky, F. "Pentafluoro-orthotellursaure, HOTeF5" Angew. Chem. 1964. 76(9), 379-380, doi:10.1002/ange.19640760912.
- Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- Mercier, H. P.A.; Sanders, J. C. P.; Schrobilgen, G. J. "The Hexakis(pentafluorooxotellurato)pnictate(V) Anions, M(OTeF5)6− (M = As, Sb, Bi): A Series of Very Weakly Coordinating Anions" Journal of the American Chemical Society, volume 116, 2921, (1994). doi:10.1021/ja00086a025.
Further reading
- R.B. King; Inorganic Chemistry of Main Group Elements, VCH Publishers, New York,1994.