Chemical elements
  Phosphorus
    Isotopes
    Energy
    Preparation
    Applications
    Physical Properties
    Chemical Properties
      Alkali Phosphides
      Alkaline Earth Phosphides
      Copper Silver and Gold Phosphides
      Zinc Group Phosphides
      Aluminium Phosphide
      Titanium Group Phosphides
      Tin Phosphides
      Lead Phosphides
      Arsenic Phosphides
      Antimony Phosphides
      Bismuth Phosphides
      Chromium Phosphides
      Molybdenum and Tungsten Phosphides
      Manganese Phosphides
      Iron Phosphides
      Cobalt Phosphides
      Phosphonium Chloride
      Phosphonium Bromide
      Phosphonium Iodide
      Hydrogen Phosphides
      Alkylphosphines
      Phosphorus Trifluoride
      Phosphorus Pentafluoride
      Phosphorus Trifluorodichloride
      Phosphorus Trifluorodibromide
      Fluophosphoric Acid
      Phosphorus Dichloride
      Phosphorus Trichloride
      Phosphorus Pentachloride
      Phosphorus Chlorobromides
      Phosphorus Chloroiodides
      Phosphorus Tribromide
      Phosphorus Pentabromide
      Phosphorus Diiodide
      Phosphorus Triiodide
      Phosphorus Oxytrifluoride
      Phosphorus Oxychloride
      Pyrophosphoryl Chloride
      Metaphosphoryl Chloride
      Phosphoryl Monochloride
      Phosphoryl Dichlorobromide
      Phosphoryl Chlorodibromide
      Phosphoryl Tribromide
      Metaphosphoryl Bromide
      Phosphoryl Oxyiodides
      Phosphorus Thiotrifluoride
      Phosphorus Thiotrichloride
      Phosphorus Thiotribromide
      Mixed Phosphorus Thiotrihalides
      Phosphorus Suboxides
      Phosphorus Trioxide
      Phosphorus Dioxide
      Phosphorus Pentoxide
      Hypophosphorous Acid
      Phosphorous Acid
      Meta- and Pyro-phosphorous Acids
      Hypophosphoric Acid
      Tetraphosphorus Trisulphide
      Diphosphorus Trisulphide
      Tetraphosphorus Heptasulphide
      Phosphorus Pentasulphide
      Phosphorus Oxysulphides
      Phosphorus Thiophosphites
      Phosphorus Thiophosphates
      Phosphorus Selenophosphates
      Phosphorus Sulphoselenides
      Diamidophosphorous Acid
      Phosphorus Triamide
      Monamidophosphoric Acid
      Diamidophosphoric Acid
      Triamidophosphoric Acid
      Dimetaphosphimic Acid ≡P=
      Trimetaphosphimic Acid
      Tetrametaphosphimic Acid
      Penta- and Hexametaphosphimic Acid
      Monamidodiphosphoric Acid
      Diamidodiphosphoric Acid
      Triamidodiphosphoric Acid
      Nitrilotrimetaphosphoric acid
      Monothioamidophosphoric Acids
      Thiophosphoryl Nitride
      Di- Tri-imido- and -amido-thiophosphates
      Imidotrithiophosphoric Acid =
      Phosphorus Chloronitrides
      Triphosphonitrilic Chloride
      Tetraphosphonitrilic Chloride
      Pentaphosphonitrilic Chloride
      Hexaphosphonitrilic Chloride
      Heptaphosphonitrilic Chloride
      Triphosphonitrilic Bromide
      Phosphorus Halonitrides
      Phosphorus Nitride
      Phosphine
      Pyrophosphoric Acid
      Phosphoric acids
    Slow Oxidation
    Phosphatic Fertilisers

Penta- and Hexametaphosphimic Acid






Pentametaphosphimic Acid and Hexametaphosphimic Acid were similarly obtained by hydrolysis in ethereal solution of the corresponding nitrilo-chlorides. Like the lower polymers they gave crystalline sodium salts containing water of crystallisation, and anhydrous penta- and hexa-silver salts by the use of ammoniacal silver nitrate. The free acids can be regenerated by the action of H2S on the silver salts. The acids are more stable towards hydrolysing agents than is trimetaphosphimic acid.

These acids may be regarded as the lactams of amidopolyimido- phosphoric acids, and the first stage in the hydrolysis probably consists in the formation of these open-chain acids, thus

[HN(PO)OH]n + H2O = H2N{HN(PO)OH}n-1(PO)(OH)2

The hydrolysis of heptaphosphorus chloronitride appears to yield at once the hydrated open-chain compound of the type shown on the right-hand side of the above equation, in which n is 7. Heptasodium and heptasilver salts of this acid have been prepared.


Amides and Imides of Condensed Phosphoric Acids

These may be regarded as derivatives of diphosphoric acid (pyrophosphoric), tri- and tetra-phosphoric acids, etc., i.e. , etc., by the substitution of =NH for =O or of -NH2 for hydroxyl in these open-chain compounds. The possibilities of isomerism are evidently very numerous, since either the amido- or the imido-replacement gives the same empirical formula. The general method of preparation consists (a) in the hydrolysis of the metaphosphimic acids already described, or (b) in heating, or fractionally precipitating with alcohol, the products of the reactions between POCl3 and NH3.
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