(Hive Addict)
06-14-04 22:17
No 513370
(Rated as: excellent)
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
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