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

Monamidophosphoric Acid, NH2PO(OH)2






Monamidophosphoric Acid, NH2PO(OH)2, has been obtained by several reactions, among which are the hydrolysis of diphenyl amidophosphate by means of alkali, thus

NH2PO(OC6H5)2 + 2NaOH = NH2PO(OH)2 + 2C6H5ONa

and the action of nitrous acid on diamidophosphoric acid. The sodium salt (which results in the former method) may be converted into the lead salt, which may then be decomposed by hydrogen sulphide at 0° C. The acid is precipitated from the filtrate by alcohol in the form of tabular or cubic crystals. It is very soluble in water, has a sweetish taste, and is hydrolysed after long standing at room temperature or rapidly in hot solution, into ammonium dihydrogen phosphate, thus

NH2PO(OH)2 + H2O = NH4OPO(OH)2

Ammonium and hydroxylamine salts of this acid furnish interesting examples of isomerism. Thus, ammonium hydrogen amidophosphate, NH2PO(OH)ONH4 (prepared by double decomposition between the silver salt and ammonium sulphide, with subsequent precipitation with alcohol as needle-shaped crystals), is isomeric with hydrazine phosphite, N2H4.H3PO3, while hydroxylamine amidophosphate, NH2PO(OH)(ONH3OH), is isomeric with hydrazine phosphate, N2H4.H3PO4.

The mono- and di-sodium salts and the corresponding potassium salts have also been prepared. The salt NH2PO(OH)(OK) was obtained by hydrolysing diphenylamidophosphate with a boiling solution of KOH, acidifying the cold solution with acetic acid and washing the precipitate with alcohol. It forms rhombohedral crystals which are very soluble in water. The solution is neutral and is gradually hydrolysed on standing. Lithium, silver and lead amidophosphates were precipitated by adding salts of these metals to alkali amidophosphates.


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