Vanadium tetrachloride

Vanadium (IV) Chloride. Vanadium(IV) chloride (vanadium tetrachloride, VCy is a red-brown hquid, is readily hydrolyzed, forms addition compounds with donor solvents such as pyridine, and is reduced by such molecules to trivalent vanadium compounds. Vanadium tetrachloride dissociates slowly at room temperature and rapidly at higher temperatures, yielding VCl and CI2. Decomposition also is induced catalyticahy and photochemically. This instabihty reflects the difficulty in storing and transporting it for industrial use. 

Minor uses of vanadium chemicals are preparation of vanadium metal from refined pentoxide or vanadium tetrachloride Hquid-phase organic oxidation reactions, eg, production of aniline black dyes for textile use and printing inks color modifiers in mercury-vapor lamps vanadyl fatty acids as driers in paints and varnish and ammonium or sodium vanadates as corrosion inhibitors in flue-gas scmbbers. 

It is clear that when the formation of a higher chloride, by the interaction between a lower chloride and chlorine is difficult, the reverse reaction, i.e., the decomposition of the higher chloride to a lower chloride and chlorine, occurs easily. For example, vanadium tetrachloride decomposes, on heating at its boiling point (148.5 °C) to the trichloride and chlorine ... 

In the production of titanium, the chlorination of rutile generates approximately 0.12 tons of waste for every ton of titanium tetrachloride produced. If ilmenite is directly chlorinated, the amount of waste is 1.5 tons for every ton of titanium tetrachloride. Large amounts of ferric chloride are produced along with volatile chlorides and oxychlorides (e.g., aluminum trichloride, silicon tetrachloride, carbon oxychloride, tin tetrachloride, vanadium tetrachloride, vanadium oxychloride) these can be removed by selective distillation. In flu-idized-bed chlorination, the build-up of liquid calcium chloride and magnesium chloride in the fluid bed interferes with the process of fluidization and hence these must be removed. 

Sodium hydride Sodium hydrosulfite Sulfur chlorides Sulfuric acid Sulfuryl chloride Tetraethyl lead Tetramethyl lead Thionyl chloride Titanium tetrachloride Toluene diisocyanate Trichlorosilane Triethylaluminum Triethylborane Triisobutylaluminum Trimethylaluminum Trimethylchlorosilane Tripropyl aluminum Vanadium tetrachloride Vinyl trichlorosilane Zirconium tetrachloride... 

At a higher temperature of 750°C vanadium tetrachloride is produced 2V2O5 + 5C + 8CI2 4VCI4 + 5CO2. 

Vanadous Chloride, vanadium trichloride, VC13.—This halide is obtained by the action of hydrogen chloride on finely divided vanadium at 300° to 400° C.,e or by heating vanadium tetrachloride to 140° C. in a current of carbon dioxide, which removes the chlorine formed at the same time. It can be conveniently made also by boiling vanadium oxy-trichloride, VOCl3, vanadium tetrachloride, VC14, or a mixture of both, with sulphur, under reflux. The reactions involved axe 7... 

Hypovanadic Chloride, vanadium tetrachloride, VC14, can be prepared synthetically from the lower chloride, VC13, by heating in a stream of chlorine at 600° C. Another convenient method consists in passing dry chlorine over ferrovanadium contained in a hard glass tube heated in a combustion furnace. The reaction is expressed ... 

The vanadium tetrachloride distils over and is purified from any ferric chloride present either by distillation or by extraction of the product with carbon tetrachloride, in which only the vanadium halide is soluble.2 Sulphuryl chloride, thionyl chloride, sulphur monochloride, and phosgene can all be used in the last reaction instead of chlorine, and the ferrovanadium also can be substituted by vanadium carbide, V4C3,3 nitride, VN,4 subsilicide, V2Si,5 disilicide, VSi2,8 or pentoxide.7... 

It is obvious that the combustion of a molecule of vanadium with an increasing number of molecules of chlorine is not accompanied by a gradually increasing evolution of heat. The figures show that the formation of vanadium tetrachloride (liquid) from vanadium trichloride (solid) and chlorine (gas) proceeds endothermically ... 

Vanadium tetrachloride is, in fact, stable only at high temperatures. The last figure is, however, unreliable, since it is considerably affected by (a) the experimental errors involved in the reactions (ii) and (iii) above, and (b) the heat of liquefaction of vanadium tetrachloride, which is at present unknown. 

Vandenberg (77) has found that vinylethers are polymerized by combinations of vanadium tetrachloride and triethylaluminum. Vandenberg believed that the intermediate vanadium trichloride, produced by reduction of the vanadium tetrachloride, reacted with the triisobutyl-aluminum-tetrahydrofuran complex to produce the modified Friedel-Crafts catalysts that converted the vinylether to isotactic polymer. 

Karapinka, Smith, Carrick (79) studied the use of methyltitanium trichloride as a catalyst for polyethylene. Alone it was inactive for the polymerization of polyethylene. It required the predecomposition to titanium trichloride at 120° or the addition of titanium trichloride to produce an active catalyst. Vanadium tetrachloride also produced an active catalyst. Aluminum bromide failed to activate the catalyst, whereas trialkylaluminum which reacts to produce alkylaluminum chlorides was effective. 

Chlorides Vanadium dichloride VCI2, green crystalline solid, a strong reducing agent vanadium trichloride VCI3, pink crystalline solid vanadium tetrachloride VC14, reddish-brown liquid, bp 148 0... 

The product is colored red by the presence of vanadium tetrachloride and contains considerable dissolved chlorine. These impurities may be removed by fractional distillation followed by a distillation from metallic sodium. The last few milliliters of vanadium oxytrichloride should not be removed from the sodium by a direct flame, as superheating often causes an explosion. A fractionating udder is convenient for collecting the product without exposing it to the moisture in the air. The side tube should be connected to a drying tube. Yield 70 g. (87 per cent of theory) boiling point 124.5 to 125.5° at 744 mm. 

If prepared from vanadium tetrachloride and trimethylsilylazide, dangerously sensitive vanadium(IV) azide trichloride appears as a byproduct. An alternative route is recommended. 

Vanadium azide tetrachloride, 4160 Vanadium dichloride, 4112 Vanadium(III) oxide, 4849 Vanadium tetrachloride, 4171 Vanadium tribromide oxide, 0291 Vanadium trichloride, 4153 Vanadium trinitrate oxide, 4758 Vanadium, 4918 Vanadium(V) oxide, 4860... 

These are usually reactions of anhydrous transition and B metal halides with dry alkali metal salts such as the sulphides, nitrides, phosphides, arsenides etc. to give exchange of anions. They tend to be very exothermic with higher valence halides and are frequently initiated by mild warming or grinding. Metathesis is described as a controlled explosion. Mixtures considered in the specific reference above include lithium nitride with tantalum pentachloride, titanium tetrachloride and vanadium tetrachloride, also barium nitride with manganese II iodide, the last reaction photographically illustrated. 

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