Hexachlorophosphazene

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Hexachlorophosphazene
Hexachlorophosphazene
Hexachlorophosphazene
IUPAC name Hexachlorotriphosphazene
Other names Phosphonitrilic chloride
1,3,5,2,4,6-Triazatriphos-
phorine-2,2,4,4,6,6-hexachloride
1,3,5-Triaza-2,4,6-triphos-
phorin-2,2,4,4,6,6-hexachloride
Hexachlorocyclotriphosphazene
Identifiers
CAS number [940-71-6]
Properties
Molecular formula N3Cl6P3
Molar mass 347.66 g/mol
Appearance colorless crystals
Density 1.98 g/mL at 25 °C
Melting point

112-115 °C
Boiling point

decomp.
Solubility in water dec.
Solubility in other solvents soluble in chlorocarbons
Structure
Dipole moment 0 D
Hazards
Main hazards mild irritant
R-phrases 14-34
S-phrases 26-36/37/39-45
Flash point n.a.
Related compounds
Related compounds PCl5
POCl3
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Hexachlorophosphazene is the chemical compound with the formula N3Cl6P3. It is a cyclic compound, whose chemical formula is more descriptively written as (PNCl2)3. It is a trimer of the hypothetical compound N≡PCl2.

Contents

[edit] Synthesis

The reaction of PCl5 and NH4Cl affords substances with the empirical formula PNCl2:[1] Purification by sublimation gives mainly the trimer (PNCl2)3 and tetramer (PNCl2)4. These rings were characterized by Liebig in his study of the reaction of PCl5 and NH3:

PCl5 + NH4Cl → 1/n(NPCl2)n + 4 HCl

Typical solvents are chlorobenzene.

[edit] Inorganic rings

Chemists have long known of rings containing carbon, e.g. benzene, pyridine, and cyclohexane. Related cyclic compounds lacking in carbon have been the subject of focused study. Hexachlorophosphazene is an archetype of this class of inorganic rings. Others include borazine, S4N4, and cyclic siloxanes.

[edit] "Inorganic rubber"

Hexachlorophosphazene has attracted considerable interest as a precursor to "inorganic rubber".[2] Upon heating to ca. 250 °C, the trimer polymerizes to give the linear polymer (PNCl2)n via a ring-opening polymerization process. This polymer is soluble in organic solvents such as THF and benzene, wherein it can be derivatized by replacement of the P-Cl bonds with P-OR or P-NR2 bonds (R = alkyl, aryl). The organically modified polymer is hydrolytically stable and exhibits some attractive properties such as low glass transition temperatures.

[edit] References

  1. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  2. ^ Mark, J. E.; Allcock, H. R.; West, R. “Inorganic Polymers” Prentice Hall, Englewood, NJ: 1992. ISBN 0-13-465881-7.
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