preparation of POCl3 / PCl5

[psyloxy]

preparation of phosphorylchloride

The action of P₂O₅ upon CCl₄ was examined. While heating 1 mole P₂O₅ with 2 to 3 moles of CCl₄ at 200-210°C for 48h  the P₂O₅ disappears and COCl₂ forms by the equation:
P₂O₅ + 2 CCl₄ ^__> COCl₂ + CO₂ + 2 POCl₃

80% of the theoretical amount of phosgene were obtained. A part of the CCl₄ always remains unchanged. Reducing the amount of CCl₄ while that of the P₂O₅ stays the same, less COCl₂ is formed until finally only traces are obtained. The reaction would then be expressed by:
2 P₂O₅ + 3 CCl₄ ^__> 4 POCl₃ + 3 CO₂

After the POCl₃ is distilled off, a thick colorless mass remains, a product of reaction between POCl₃ and excessive P₂O₅

Chem.Ber. - 5.1872;30

J. Am. Chem. Soc.; Vol. 63; ( 1941 ) 1782 - 1789. P₂O₅ w/NaCl at ~250°C gives POCl₃

H.A. Curtis, R.L. Copson and A.J. Abrams, Chem. and Met. Eng., 44, No. 3, 140-142 - 1937 Article referenced in the one above

Patent BP356238

Example I

A mixture of tricalcium phosphate and carbon in excess is dried and mixed with 5% of zinc chloride. This mixture is heated to 500-600°C while a stream of chlorine is conducted over it. The reaction takes place easily, phosphorous-chlorine compounds being formed, which distil over with the carbon monoxide also produced, while calcium chloride remains as residue.

POCl₃ procedures:

Patent US2829031

: H₃PO₄ is sprayed onto residue from sugar cane and chlorinated at 550°C ;

Patent US2712494

: granular charcoal (soaked with H₃PO₄) is chlorinated between 500 and 700°C
C. A.; 1954; 9028 : 75 to 80 % H₃PO₄ is concentrated and with addition of granular, powdered charcoal dried and treated with Cl₂ at 400 to 500°C

Patent US1688503

: Ca₃(PO₄)₂ + 8 SiO₂ + 10 NaCl ^__> 2 PCl₅ + 3 CaSiO₃ + 5 Na₂SiO₃ ; 1100 - 1400°C

--psyloxy--