940-71-6

white crystalline powder

Hexachlorocyclotriphosphazene (PNCl2)3 (mp114 ℃, bp 256℃), which is produced on an industrial scale as the starting material for the manufacture of organosubstituted polyphosphazenes. It forms an almost planar six-membered ring with equal P?N bond lengths.

Purify it by zone melting, by crystallisation from pet.ether, n-hexane or *benzene, and by sublimation. [van der Huizen et al. J Chem Soc, Dalton Trans 1311 1986, Meirovitch et al. J Phys Chem 88 1522 1984, Alcock et al. J Am Chem Soc 106 5561 1984; Winter & van de Grampel J Chem Soc, Dalton Trans 1269 1986.] Phosphoric acid [7664 -38 -2] M 98.0, m 42.3o, pK 1 2.15, pK 2 7.21, pK 3 12.37. Pyrophosphate can be removed from phosphoric acid by diluting with distilled H2O and refluxing overnight. By cooling to 11o and seeding with crystals obtained by cooling a few millilitres in a Dry-ice/acetone bath, 85% orthophosphoric acid crystallises as H3PO4.H2O. The crystals are collected on a sintered glass filter. [Weber & King Inorg Synth I 101 1939.]