Chemical elements
  Uranium
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
    Compounds
      Uranium Difluoride
      Uranium Tetrafluoride
      Uranous Oxyfluoride
      Uranium Hexafluoride
      Uranyl Fluoride
      Uranium Trichloride
      Uranium Tetrachloride
      Uranium Pentachloride
      Uranyl Chloride
      Uranyl Chlorate
      Uranyl Perchlorate
      Uranium Tetrabromide
      Uranyl Bromide
      Uranium Tetra-iodide
      Uranyl Iodide
      Uranyl Iodate
      Uranous Oxide
      Uranous Hydroxide
      Uranium Pentoxide
      Urano-uranic Oxide
      Uranium Trioxide
      Ammonium Diuranate
      Ammonium Hexa-uranate
      Hydroxylamine Uranate
      Hydroxylamine Potassio-uranate
      Barium Uranate
      Barium Diuranate
      Bismuth Uranate
      Iron Uranate
      Lithium Uranate
      Potassium Uranate
      Potassium Diuranate
      Potassium Tetra-uranate
      Potassium Hexa-uranate
      Rubidium Uranate
      Silver Diuranate
      Sodium Uranate
      Sodium Diuranate
      Sodium Triuranate
      Sodium Penta-uranate
      Strontium Uranate
      Zinc Uranate
      Peruranic acid
      Ammonium Peruranate
      Barium Peruranates
      Lithium Peruranate
      Nickel Peruranate
      Potassium Peruranate
      Sodium Peruranates
      Uranium Monosulphide
      Uranium Sesquisulphide
      Uranium Disulphide
      Uranium Oxysulphide
      Uranyl Sulphide
      Uranium Sulphite
      Uranyl Sulphite
      Complex Uranyl Sulphites
      Uranium Sulphate
      Uranium Dithionates
      Uranyl Sulphate
      Uranyl Pyrosulphate
      Uranyl Thiosulphate
      Uranyl Dithionate
      Uranium Sesquiselenide
      Uranium Diselenide
      Uranyl Selenide
      Uranyl Selenite
      Uranyl Selenate
      Uranium Telluride
      Uranium Nitrides
      Uranous Nitrate
      Uranyl Nitrate
      Uranium Monophosphide
      Uranous Phosphide
      Uranyl Hypophosphite
      Uranyl Phosphite
      Uranous Phosphates
      Uranyl Phosphates
      Complex Uranyl Phosphates
      Uranyl Aminophosphates
      Uranous Arsenide
      Uranyl Metarsenite
      Uranous Arsenate
      Uranyl Arsenates
      Complex Uranyl Arsenates
      Uranous Antimonide
      Uranous Antimonate
      Uranium Carbide
      Complex Uranyl Carbonates
      Ammonium Uranyl Carbonate
      Calcium Uranyl Carbonate
      Potassium Uranyl Carbonate
      Sodium Uranyl Carbonate
      Thallium Uranyl Carbonate
      Potassium Uranyl Ferrocyanide
      Uranyl Platinocyanide
      Uranyl Cyanate
      Uranyl Thiocyanate
      Uranium Silicide
      Uranium Boride
      Uranyl Perborate
    PDB 1anv-3pu4

Uranium Tetrachloride, UCl4






Uranium Tetrachloride, Uranous Chloride, UCl4, may be prepared by heating uranium, uranium carbide, or a mixture of any oxide of uranium, or uranyl chloride, with carbon, in a stream of chlorine. A small quantity of the pentachloride is also formed, but this may be converted to the tetrachloride by heating at 235° C. in a current of carbon dioxide. Uranous chloride may also be obtained by the action of gaseous hydrogen chloride on uranous oxide; or by heating urano-uranic oxide in a current of carbon tetrachloride vapour, or in a mixture of chlorine and sulphur chloride. The product can be purified by sublimation in a vacuum, or by heating to redness in an atmosphere of dry chlorine. In the latter case, a hard glass tube, of about 4 cm. diameter, may be used; the uranous chloride is deposited close to the hot zone in the form of a green crystalline mass. It may be obtained in solution by exposing to the action of sunlight a solution in hydrochloric acid of uranic hydroxide, or of the green hydroxide, in presence of a little alcohol; or by reduction of uranyl chloride by means of copper and hydrochloric acid in presence of traces of platinic chloride; it is obtained as a green crystalline precipitate on adding ether.

Uranous chloride yields lustrous, dark green, octahedral crystals which sublime when heated to redness. The vapour density is 13.33 (air = 1), corresponding to molecular weight 386.0 (UCl4 = 380.0). By ebullioscopic determinations of the molecular weight, using molten bismuth chloride as solvent, Riigheimer and Gonder obtained the value 373. The crystals fume in the air and are very deliquescent. They readily dissolve in water, with evolution of heat, yielding a green solution which is fairly stable in the cold, but is hydrolysed to a considerable extent and gives an acid reaction. It is a powerful reducing agent, and on evaporation, hydrochloric acid fumes escape, and on prolonged heating or boiling, a black precipitate is produced which appears to be an oxychloride of composition UCl4.5UO2.10H2O. On complete evaporation an amorphous deliquescent mass is obtained which when heated leaves urano-uranic oxide. Uranous chloride dissolves readily in ethyl alcohol, acetone, and other organic solvents.

It is reduced to the metal by the action of alkali metals. Heated in hydrogen, it yields the trichloride; in ammonia, a nitride; in hydrogen sulphide, a sulphide.

The oxychloride, UCl4.2UO2.13H2O, may be obtained as green crystals by the action of light on a solution of uranyl chloride in a mixture of alcohol and ether. When dried over sulphuric acid the salt loses water and leaves the monohydrate, UCl4.2UO2.H2O. This on heating at 100° C. becomes brownish-black and yields UCl4.4UO2. Both hydrates dissolve in water and alcohol, forming green solutions.

Double Chlorides of the type R2UCl6 (R = Na, K, Li; R2 = Ca, Sr, Ba) have been obtained by passing uranous chloride vapour over the chloride of the alkali or alkaline earth metal heated to dull redness. The salts, which are green, are hygroscopic, and darken as they absorb moisture from the air. They are unstable, and their solutions oxidise slowly at ordinary temperature and more rapidly when heated. When evaporated in a vacuum over sulphuric acid they decompose, so that the salts cannot be obtained in the crystalline form.

The double salt, uranous chlorophosphate, UCl4.UH2(PO4)2, separates in green crystals from a solution of uranous phosphate, UH2(PO4)2.5H2O, in concentrated hydrochloric acid. A chlorophosphate, of composition UCl4.3UO2.2P2O5, has also been prepared.


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