Hypophosphorous acid, disproportionation

The fact that the element readily dissolves in aqueous media with disproportionation into PH3 and an oxoacid is immediately clear from the fact that P lies above the line joining PH3 and either H3PO2 (hypophosphorous acid), H3PO3 (phosphorous acid) or H3PO4 (orthophosphoric acid). Phe reaction is even... 

Free hypophosphorous acid is obtained by acidifying aqueous solutions of hypophosphites but the pure acid cannot be isolated simply by evaporating such solutions because of its ready oxidation to phosphorous and phosphoric acids and disproportionation to phosphine and phosphorous acid (Fig. 12.16). Pure H3PO2 is obtained by continuous cxiraction from aqueous solutions into Ft 0 it forms white crystals mp... 

It can also be prepared by disproportionation of phosphorous acid or hypophosphorous acid, or by direct combination of the elements under pressure and high temperature. 

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