Should be oxidized to phosphoric acid by careful oxidation in aq. In air-tight plastic bottles, away from light and oxidizers. Reduction may generate phosphine, which is very toxic and flammable. HPA is a mid-strength acid, irritant and corrosive. Reduction of arenediazonium salts to arenes.Pure anhydrous hypophosphorous acid however, can be obtained by the continuous extraction of its aqueous solution with diethyl ether. The hypophosphite salt is then treated with a strong, non-oxidizing acid to give the free hypophosphorous acid:Īnhydrous acid cannot be obtained by simple evaporation of the water, as the acid ready oxidizes to phosphorous acid and phosphoric acid, as well as disproportionates to phosphorous acid and phosphine. White phosphorus is carefully added to hot aqueous solution of an alkaline hydroxide, like NaOH or even Ca(OH) 2. solution.īecause hypophosphorous acid can reduce elemental iodine to form hydroiodic acid, which is a reagent effective for reducing ephedrine or pseudoephedrine to methamphetamine, the United States Drug Enforcement Administration designated hypophosphorous acid (and its salts) as a List I precursor chemical and thus cannot be acquired by the hobby chemist. It is sold by chemical suppliers, as 50% aq. Hypophosphorous acid is a colorless, deliquescent solid at standard conditions, that readily melts above 26.5 ☌ and due to its strong hygroscopicity, it cannot be solidified again without decomposition in open air. H 3PO 2 + 2 Cr 2O 3 → 4 CrO + H 3PO 4 Physical

Hypophosphorous acid can reduce chromium(III) oxide to chromium(II) oxide:

Hypophosforus acid sythesis meth