Organophosphinic acid

The Cyanex family of dialkylphosphinic acids are used in hydrometallurgy to extract metals from ores.

Phosphinic acid adds to Michael acceptors, for example with acrylamide it gives H(HO)P(O)CH2CH2C(O)NH2.

Under the brand names Aerophine and Cyanex, dialkylphosphinic acids are used in extraction and separation of metals as one of the techniques of hydrometallurgy[1] 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.

chemical structure of a dialkylphosphinic acid called Cyanex 272.
Chemical structure of the dithiophosphinic acid called Cyanex 301