Dialkylphosphinic acid

Dialkylphosphinic acids are organophosphorus compounds with the formula R₂PO₂H, where R is any alkyl group. They are phosphorus(V) compounds with tetrahedral molecular geometry. Under the brand names Aerophine and Cyanex, they are used in extraction and separation, i.e., hydrometallurgy, of metal salts from ore extracts. Characteristically the organic substituents are branched to confer solubility and preclude crystallization.

The dithiodialkyphosphinic acids (R₂PS₂H) are related to the diorganodithiophosphates with the formula (RO)₂PS₂H, which are also used as complexing agents in the purification of metals. The phosphates are more prone to hydrolysis owing to the greater lability of the RO-P linkage vs the direct C-P bond.