Chemical elements
  Phosphorus
    Isotopes
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    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

Phosphorus Thiotrichloride, PSCl3






Phosphorus Thiotrichloride or thiophosphoryl chloride, PSCl3, has been prepared by many reactions:—

  1. The first method, which led to the discovery of this compound, was by the action of H2S on PCl5, with elimination of HCl, thus;—

    H2S + PCl5 = PSCl3 + 2HCl

    The H2S may be supplied in the liquid form.
  2. Some sulphides of the non-metals yield their sulphur to PCl5 in exchange for chlorine:—

    CS2 + 2PCl5 = 2PSCl3 + CCl4
    P2S5 + 3PCl5 = 5PSCl3 (in a sealed-tube at 120°)

    Compare also:

    Sb2S3 + 3PCl5 = 2SbCl3 + 3PSCl3
  3. Sulphur combines directly with PCl3 in a sealed tube at 130° C.:—

    PCl3 + S = PSCl3
  4. Sulphur monochloride combines when heated with phosphorus, thus:—

    2P + 3S2Cl2 = 2PSCl3 + 4S
  5. Sulphur monochloride reacts with phosphorus trichloride in the presence of iodine, thus:—

    3PCl3 + S2Cl2 = 2PSCl3 + PCl5
  6. Thionyl chloride when heated with tetraphosphorus decasulphide in a closed tube at 100° to 150° C. reacts according to the equation

    P4S10 + 6SOCl2 = 4PSCl3 + 3SO2 + 9S


Properties

Thiophosphoryl chloride is a transparent colourless liquid which fumes in the air and smells of hydrogen sulphide. The formula has been established by analysis and vapour density determination. The density of the liquid is 1.66820 at 0° C. and 1.45599 at the normal boiling-point, 125.12° C. The coefficient of expansion between these temperatures is given by

vt = v0(1 + 0.0399011t + 0.0690302t2 + 0.083825t3)

The melting-point is -35° C.

Thiophosphoryl chloride decomposes when passed through a red-hot tube, giving PCl3, S and S2Cl2. An excess of chlorine combines with both the other elements, according to the equation

2PSCl3 + 3Cl2 = 2PCl5 + S2Cl2

The compound is reduced slowly by hydrogen iodide, giving PI3, H2S, HCl and sulphides of phosphorus. Like other halides of phosphorus it combines with dry ammonia, giving a white solid, which may contain from 30 to 60 per cent, of NH3. This product is said to contain thiophosphoryl diaminochloride, P(NH2)2ClS, or thiophosphoryl triamine, P(NH2)3S.

Thiophosphoryl chloride dissolves sulphur and phosphorus freely when hot, but only sparingly when cold. Since the liquid is immiscible with water the hydrolysis proceeds only on the surface at first, as is usual with phosphorus halides. In this case the products are phosphoric acid, hydrogen chloride and sulphide and a little sulphur. It reacts with ethyl alcohol, giving ethyl chloride and ethyl thiophosphate:

3C2H5OH + PSCl3 = (C2H5)H2PSO3 + 2C2H5Cl + HCl

Thiophosphates can also be made from the thiochloride with sodium ethoxide and aqueous alkalies.
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