Metaphosphoryl Chloride, PO₂Cl

Metaphosphoryl Chloride, PO₂Cl, was prepared by heating P₂O₅ with POCl₃ in a sealed tube at 200° C. for 36 hours, thus

P₂O₅ + POCl₃ = 3PO₂Cl₂

and also by the slight hydrolysis of POCl₃ in moist air. Being the least volatile of the chlorides of phosphoric acid it is found in the residues after the others have been fractionally distilled. It has been made in several other ways, including the regulated action of chlorine gas on phosphorous oxide:—

4Cl₂ + P₄O₆ = 2POCl₃ + 2PO₂Cl

It is a syrupy liquid which decomposes into P₂O₅ and POCl₃ when heated.