Hypophosphorous acid reducing action

The fact that phosphorus tetroxide, P204, furnishes phosphoric and phosphorous acids when treated with water is expressed by the structural formula 0=P=03=P. If phosphorus tetroxide be the anhydride of hypophosphoric acid—vide supra—it might be anticipated that 0=P 03=P- -2H20->0(0H)2P—0— P(0H)2. If the last formula really represented the structure of hypophosphoric acid, it would follow that (i) this acid would be a reducing agent like phosphorous acid, but it is not and that (ii) it ought to be possible to prepare at least two isomers by the action of sodium hydroxide on dipotassium hypophosphate, and of potassium hydroxide on disodium hypophosphate, say ... 

Another method consists of reducing the dinitroaminophenylarsinic acid with alcoholic hypophosphorous acid, 4 it -diamino-Z 5 8 5 -tetranitroarsenobenzene resulting, and this on treatment with stannous chloride in concentrated hydrochloric acid yields the hexamino-base. Reduction of the dinitro-compound has also been effected by treating it with sodium hydrosulphite, and by the action of ferrous chloride in alkaline solution. ... 

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