Teflic acid

Teflic acid
Structural formula
Space-filling model
Space-filling model
Names
IUPAC name
Pentafluoroorthotelluric acid
Other names
Teflic acid
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.161.534 Edit this at Wikidata
  • InChI=1S/F5HOTe/c1-7(2,3,4,5)6/h6H checkY
    Key: OAOSLENTGBMCNC-UHFFFAOYSA-N checkY
  • InChI=1/F5HOTe/c1-7(2,3,4,5)6/h6H
    Key: OAOSLENTGBMCNC-UHFFFAOYAO
  • F[Te](F)(F)(F)(F)O
Properties
HOTeF5
Molar mass 239.60 g·mol−1
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)
Acidity (pKa) 8.8 (in Ac2O)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 corrosive, toxic
GHS labelling:
GHS05: Corrosive
Danger
H314
P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Teflic acid is a chemical compound with the formula HOTeF5. This strong acid is related to orthotelluric acid, Te(OH)6. Teflic acid has a slightly distorted octahedral molecular geometry.

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, containing HOTeF5:

BaTeO4 + 10 FSO2OH → HOTeF5 (25%)

Teflic acid can also be prepared from fluorosulfonic acid and barium tellurate:

5 FSO2OH + Ba2+[TeO2(OH)4]2− → HOTeF5 + 4 H2SO4 + BaSO4

It is also the first hydrolysis product of tellurium hexafluoride:

TeF6 + H2O → HOTeF5 + HF

A more recent synthetic route uses elemental tellurium as the starting material. In the first step, tellurium reacts with chlorine, potassium fluoride and water to give potassium pentafluoroorthotellurate (KOTeF5):

Trichloroisocyanuric acid (TCICA) can be used as the oxidant in place of elemental chlorine. In the second step, the salt is protonated with sulfuric acid to yield teflic acid:

Teflates

Boron teflate

The conjugate base of teflic acid is called the teflate anion, F5TeO− (not to be confused with triflate). Many teflates are known, one example being B(OTeF5)3, that can be pyrolysed to give acid anhydride O(TeF5)2.

2 B(OTeF5)3 → 2 B(OTeF5)2F + O(TeF5)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 (in which M = As, Sb, Bi). Xenon forms the cation Xe(OTeF5)+.

References

  1. ↑ Perrin, D. D., ed. (1982) [1969]. Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution. IUPAC Chemical Data (2nd ed.). Oxford: Pergamon (published 1984). Entry 220. ISBN 0-08-029214-3. LCCN 82-16524.
  2. ↑ Engelbrecht, A.; Sladky, F. "Pentafluoro-orthotellursaure, HOTeF5" Angewandte Chemie 1964. 76(9), 379-380, doi:10.1002/ange.19640760912.
  3. 1 2 Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  4. ↑ Simon, Claire; Steinhauer, Simon; Wiesner, Anja; Riedel, Sebastian (2026). "Facile Synthesis of Pentafluoroorthotelluric Acid". Israel Journal of Chemistry. 66 (5): e70041.
  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