Chemical elements
    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
      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
      Pyrophosphoric Acid
      Phosphoric acids
    Slow Oxidation
    Phosphatic Fertilisers

Triamidodiphosphoric Acid, (NH2)3P2O3(OH)

Triamidodiphosphoric Acid, (NH2)3P2O3(OH), was prepared by similar reactions. It formed a series of salts in which it was monobasic. But in addition to the white monosilver salt, (NH2)3P2O3(OAg), an orange-coloured trisilver salt was prepared from ammoniacal silver nitrate, to which the constitution NH2(NHAg)2P2O3(OAg) was assigned.

Amido- and imido- derivatives of condensed phosphoric acid of still higher molecular weight have been prepared in great variety by Gladstone, and by Stokes. For example, monoimidotetramido- tetraphosphoric acid, NH=P4O7(NH2)4, has been obtained by heating the product of general reaction (b) to about 200° C., while tetramidotetraphosphoric acid, (HO)2P4O7(NH2)4, was obtained by hydrolysing ammonium diamidotetraphosphate either with acids or with alkalies, thus

(NH2)2P4O7(OH)(ONH4)3 + HCl = (NH2)4P4O7(OH)2 + NH4Cl + 2H2O

The structures assigned were


Many other derivatives have been obtained. Their general properties have already been indicated.

The imidodiphosphoric acids are isomeric with amidodiphosphoric acids. Monimidodiphosphoric acid,

HN={PO(OH)2}2, or

was prepared by heating trimetaphosphimic acid, dissolving in aqueous ammonia, and adding a salt of magnesium, which precipitated magnesium ortho- and pyro-phosphates, leaving a soluble magnesium salt which on treatment with ammoniacal silver nitrate gave a crystalline precipitate of NH=P2O2(OAg)3OH. This, when treated with sodium chloride, gave a soluble non-crystallisable trisodium salt. A tetrasilver salt has also been prepared in two modifications—as a voluminous white precipitate which on boiling passes into a yellow form. These may have the imido- and the amido-structures respectively.

A dibasic imidodiphosphoric acid, which can be regarded as derived from the last-mentioned compound by the loss of the elements of water, was prepared by warming to about 50° C. a solution of 4 grams ammonium carbamate in 10 grams of phosphoryl chloride. Thus

3NH2COONH4 + 4POCl3 = 2NH(POCl2)2 + 3CO2 + 4NH4Cl
NH(POCl2)2 + 3H2O = NH(POOH)2O + 4HCl

The barium or ferric salt may be precipitated, and from the former the free acid may be regenerated. Other derivatives were prepared by similar reactions.

Nitrilophosphoric Acids

These compounds, in which trivalent nitrogen bridges phosphoryl radicals, are obtained by heating amido-compounds, with loss of ammonia.

The potassium salt of nitrilodiphosphoric acid,

was obtained by heating potassium triamidodiphosphate, the ammonium salt by heating triamidodiphosphoric acid, and the silver salt by interaction between silver nitrate and a suspension of the sparingly soluble potassium salt in water.
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