Phosphorus Suboxides

A solid substance said to be tetraphosphorus monoxide, or phosphorus tetritoxide, P₄O, has been prepared by a number of reactions, amongst which may be mentioned the slow oxidation of phosphorus in ether, and the reduction of phosphorus pentoxide with ammonia, followed by treatment to remove other oxides, namely, washing and evacuation. The removal of water from hypophosphorous acid is said also to yield this product, thus

4H₃PO₂ = P₄O + O + 6H₂O

Acetic anhydride in the presence of glacial acetic acid has been used as the dehydrating agent. A solution of phosphorus in 10 per cent, aqueous caustic soda with twice its volume of alcohol yielded on acidification a greenish-yellow solid to which the same composition was assigned. The substance prepared by various methods has a red or orange colour and a density of about 1.9. It is a mixture, the composition of which may be inferred from the facts that it retains hydrogen and moisture, that it gives phosphorus and phosphorus pentoxide when heated in an indifferent gas, and that when distilled in chlorine it yields phosphorus oxychloride as well as the pentachloride.

The supposed compound P₂O is also a mixture of finely divided phosphorus with phosphorous acid.