Chemical elements
    Physical Properties
    Chemical Properties
      Hypovanadous Oxide
      Vanadous Oxide
      Hypovanadic Oxide
      Vanadic Oxide
      Hypovanadous Fluoride
      Vanadous Fluoride
      Vanadium Tetrafluoride
      Vanadium Pentafluoride
      Vanadyl Difluoride
      Vanadium Oxytrifluoride
      Vanadium Dioxyfluoride
      Hypovanadous Chloride
      Vanadous Chloride
      Hypovanadic Chloride
      Divanadyl Chloride
      Vanadium Oxymonochloride
      Vanadyl Dichloride
      Vanadium Oxytrichloride
      Vanadium Oxydichloride
      Vanadous Bromide
      Hypovanadic Bromide
      Vanadium Oxymonobromide
      Vanadyl Dibromide
      Vanadium Oxytribromide
      Hydrated Vanadium Tri-iodide
      Vanadium Suboxide
      Hypovanadous Oxide
      Vanadous Oxide
      Hypovanadic Oxide
      Intermediate Vanadium Oxides
      Vanadium Pentoxide
      Sodium Stannovanadates
      Double Vanadates
      Heteropoly-Acids with Vanadium
      Pervanadic Acid
      Vanadium Monosulphide
      Vanadium Trisulphide
      Vanadium Pentasulphide
      Vanadium Oxysulphides
      Hypovanadous Sulphate
      Vanadous Sulphate
      Vanadyl Sulphites
      Vanadyl Sulphates
      Vanadic Sulphates
      Vanadyl Dithionate
      Ammonium Orthothiovanadate
      Ammonium Pyroxyhexathiovanadate
      Sodium Orthoxytrithiovanadate
      Sodium Orthoxymonothiovanadate
      Vanadium Selenides
      Vanadyl Selenite
      Vanadyl Selenates
      Vanadium Subnitride
      Vanadium Mononitride
      Vanadium Dinitride
      Alkali Vanadyl Nitrites
      Vanadium Nitrates
      Vanadyl Hypophosphite
      Vanadyl Phosphates
      Vanadous Pyrophosphate
      Vanadyl Arsenates
      Vanadium Carbide
      Vanadyl Cyanide
      Potassium Vanadocyanide
      Potassium Vanadicyanide
      Vanadium Ferrocyanides
      Ammonium Vanadyl Thiocyanate
      Vanadium Subsilicide
      Vanadium Disilicide
      Vanadium Boride
    Detection, Estimation
    PDB 1b8j-2i4e
    PDB 2jhr-6rsa

Vanadium Oxytrichloride, VOCl3

Vanadium Oxytrichloride, VOCl3, commonly known as "vanadyl chloride," is the easiest to prepare of all the halogen or oxyhalogen compounds of vanadium. It distils over as a yellow liquid when vanadium pentoxide is strongly heated, or when vanadiun trioxide is gently heated, in a current of chlorine. Addition of charcoal accelerates the reactions:
  1. 2V2O5 + 6Cl2 = 4VOCl3 + 3O2.
  2. 3V2O3 + 6Cl2 = 4VOCl3 + V2O5.
Instead of using chlorine, gaseous hydrogen chloride may be employed, provided that a strong dehydrating agent, phosphorus pentoxide or zinc chloride, is present to remove the water formed and so stop the right-to-left reaction in

V2O5 + 6HCl2 ⇔ VOCl3 + 3H2O.

Halogenation in the presence of sulphur, or by means of sulphur halides, is also available. When chlorine is conducted into a mixture of vanadium pentoxide and sulphur, or when powdered vanadium pentoxide is treated with sulphur monochloride vapours, an immediate reaction sets in, with formation of vanadium oxytrichloride. A quantitative yield of this compound is also obtained when vanadium trichloride is heated in oxygen at 500° to 600° C.

Vanadium oxytrichloride is a light yellow, mobile, transparent liquid, which boils at 127.15° C at 764.5 mm. Other determinations gave the As 126.7° C. at 767 mm. And 124.4° C. at 723 mm. The density has been found to be 1.8656 at 0° C., or 1.8362 at 15.5° C., compared with water at 4° C. The expansion on being heated from 0° to 130° C. has been measured. The oxytrichloride remains a liquid at -15° C., and its vapour density at 186° C. is 6.108 (air = 1), showing it to be undecomposed. It is not decomposed on prolonged boiling with metallic sodium, potassium, or magnesium. On exposure to damp air, or on being treated with a small quantity of water, it displays the usual unstable character of the pentavalent vanadium halides in that it undergoes rapid hydrolysis and thereby becomes coated with red flakes of vanadium pentoxide:

2VOCl3 + 3H2O = V2O5 + 6HCl.

With more water, it passes into solution; dilute solutions, which are brownish-yellow or red, according to the concentration, evolve chlorine and become blue on standing, undergoing reduction to the tetravalent state. On evaporation to dryness, all the chlorine is evolved and the residue consists of the pentoxide. Vanadium oxytrichloride is also soluble in ether and alcohol. It dissolves chlorine, bromine, iodine, yellow phosphorus, and sulphur, and is miscible with various liquid hydrocarbons and chlorinated hydrocarbons; its use as an industrial solvent has therefore been suggested.

Addition of pyridine hydrochloride to an alcoholic solution of vanadium oxytrichloride yields an addition compound, VOCl3.C5H5N.HCl.C2H5OH. On being brought into reaction with cupric oxide, a dark green copper chlorovanadate is formed, Cu(VO3)2.CuCl; litharge similarly yields a brick-red lead chlorovanadate, Pb(VO3)2.PbCl2. From the instability of these compounds towards water it is assumed that the chlorine atoms are directly attached to the vanadium atom. The copper salt is, therefore, formulated thus: . The reaction with magnesium oxide proceeds differently and gives magnesium hexavanadate, Mg2V6O17.19H2O.

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