Phosphorus Oxychloride: Phosphorus Trichloride and Pentoxide Chlorinated

Phosphorus oxychloride is the reagent used to make tricresyl and triphenyl phosphate plasticisers. North's method (US 1,921,370, 1933) mixes phosphorus trichloride with phosphorus pentoxide and passes chlorine in while warming and stirring: 3 PCl3 + P2O5 + 3 Cl2 = 5 POCl3. The crude liquid is then fractionated; the main cut boils at 106–107.5 °C. The fumes badly irritate lungs and throat. The picture: our diagram.