Potassium tetraphenylborate

Potassium tetraphenylborate
IUPAC name
Potassium tetraphenylboranuide
3244-41-5 N
3D model (Jmol) Interactive image
ChemSpider 4937589 YesY
ECHA InfoCard 100.156.375
PubChem 6432333
Molar mass 358.3249
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

Potassium tetraphenylborate is the salt with the formula KB(C6H5)4). It is a colourless salt that is a rare example of a water-insoluble salt of potassium.

The salt has a low solubility in water of only 1.8×10−4 g/L. It is, however, soluble in organic solvents. The insolubility of this compound has been used to determine the concentration of potassium ions by precipitation and gravimetric analysis:[1]

K+ + NaB(Ph)4 KB(Ph)4 + Na+

The compound adopts a polymeric structure with bonds between the phenyl rings and potassium. As such it is classified as an organopotassium compound.[2]


  1. Engelbrecht, R. M.; McCoy, F. A. (1956). "Determination of Potassium by Tetraphenylborate Method". Anal. Chem. 28 (11): 1772. doi:10.1021/ac60119a040.
  2. Ulrich Behrens, Frank Hoffmann, and Falk Olbrich "Solid-State Structures of Base-Free Lithium and Sodium Tetraphenylborates at Room and Low Temperature: Comparison with the Higher Homologues MB(C6H5)4 (M = K, Rb, Cs)" Organometallics 2012, volume 31, p. 905−913. doi:10.1021/om200943n

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