Potassium tetraphenylborate

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Potassium tetraphenylborate
Potassium tetraphenylborate.png
IUPAC name
Potassium tetraphenylboranuide
3D model (Jmol)
ECHA InfoCard 100.156.375
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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