Potassium tetraphenylborate

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:


 * 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.