An organophosphinic acid is an

organophosphorus compound Organophosphorus compounds are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective in ...

with the formula R_2−nH_nPO₂H (R =

alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloalk ...

aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used as ...

). One or both P-H bonds in the parent

hypophosphorous acid Hypophosphorous acid (HPA), or phosphinic acid, is a phosphorus oxyacid and a powerful reducing agent with molecular formula H3PO2. It is a colorless low-melting compound, which is soluble in water, dioxane and alcohols. The formula for this ...

(aka phosphinic acid) are replaced by organic groups. The Cyanex family of dialkylphosphinic acids are used in hydrometallurgy to extract metals from ores.

Monalkylphosphinic acids

Monalkylphosphinic acids have the formula OP(OH)(H)R, with the simplest example being methylphosphinic acid. Phosphinic acid adds to Michael acceptors, for example with

acrylamide Acrylamide (or acrylic amide) is an organic compound with the chemical formula CH2=CHC(O)NH2. It is a white odorless solid, soluble in water and several organic solvents. From the chemistry perspective, acrylamide is a vinyl-substituted primary ...

it gives H(HO)P(O)CH₂CH₂C(O)NH₂.

Dialkylphosphinic acids

Dialkylphosphinic acids have the formula R₂PO₂H, where R is an alkyl or aryl group. The phosphorus(V) center has

tetrahedral molecular geometry In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos−1(−) = 109.4712206...° ≈ 109.5° when all four substituents are ...

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

hydrometallurgy Hydrometallurgy is a technique within the field of extractive metallurgy, the obtaining of metals from their ores. Hydrometallurgy involve the use of aqueous solutions for the recovery of metals from ores, concentrates, and recycled or residual m ...

Characteristically the organic substituents are branched to confer solubility and preclude crystallization.

Formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...

and H₃PO₂ react to give (HOCH₂)₂PO₂H.

Related compounds

The dithiodialkyphosphinic acids (R₂PS₂H) are related to the

diorganodithiophosphate Dimethyl dithiophosphoric acid is the organophosphorus compound with the formula (CH3O)2PS2H. It is the processor for production of the organothiophosphate insecticide Malathion. Although samples can appear dark, the compound is a colorless, d ...

s with the formula (RO)₂PS₂H, which are also used as complexing agents in the purification of metals. The phosphates are more prone to

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

owing to the greater lability of the RO-P linkage vs the direct C-P bond.

References

{{Organophosphorus Functional groups

Monalkylphosphinic acids

Dialkylphosphinic acids

Related compounds

See also

References