What is "hypophosphorous acid"

Hypophosphorous \Hy`po*phos"phor*ous\, a. [Pref. hypo- + phosphorous.] (Chem.) Pertaining to, or containing, phosphorus in a lower state of oxidation than in phosphoric compounds; as, hypophosphorous acid.

Hypophosphorous acid (Chem.), an acid, H3PO2, whose salts are produced by the action of barium hygrate on phosphorus. It may be obtained from its water solution, by exaporation and freezing, as a white crystalline substance. It is a powerful reducing agent.

n. (context chemistry English) A pale yellow liquid, H₃PO₂, used as a reducing agent.

n. a clear or yellow-colored monobasic acid (H3PO2) [syn: phosphorous acid, orthophosphorous acid]

Hypophosphorous acid is a phosphorus oxoacid and a powerful reducing agent with molecular formula HPO. Inorganic chemists refer to the free acid by this name (also as "HPA"), or the acceptable name of phosphinic acid. It is a colorless low-melting compound, which is soluble in water, dioxane, and alcohols. The formula for hypophosphorous acid is generally written HPO, but a more descriptive presentation is HOP(O)H which highlights its monoprotic character. Salts derived from this acid are called phosphinates (hypophosphites).

HOP(O)H exists in equilibrium with the minor tautomer HP(OH). Sometimes the minor tautomer is called hypophosphorous acid and the major tautomer is called phosphinic acid.