Vanadium -, chloride

Impurities that form volatile chlorides leave as gases at the top of the furnace together with the TiCl. By cooling those gases, most impurities, with the exception of vanadium and siUcon chlorides can be separated from the titanium tetrachloride [7550-45-0]. Vanadium chlorides can be reduced to lower oxidation state chlorides that are soHds highly volatile SiCl can be removed from TiCl by fractional distillation. 

Vanadium metal can be prepared either by the reduction of vanadium chloride with hydrogen or magnesium or by the reduction of vanadium oxide with calcium, aluminum, or carbon. The oldest and most commonly used method for producing vanadium metal on a commercial scale is the reduction of V20 with calcium. Recently, a two-step process involving the alurninotherniic reduction of vanadium oxide combined with electron-beam melting has been developed. This method makes possible the production of a purer grade of vanadium metal, ie, of the quaUty required for nuclear reactors (qv). 

Vanadium chloride, chromium chloride," and the combined use of tributylphosphine and thphenyldisulfide are also effeedve in promoting the reduedve Nef reacdon. 

Vanadlum-chlorid, n. vanadium chloride, specif. vanadium(III) chloride, VCI3. -chloriir, n. vanadous chloride, vanadium (IT) chloride, VClj. -eisen, n. ferrovanadium. 

When sodium or potassium is added too quickly to vanadium chloride, this gives rise to a violent detonation. If it is done without caution, the reaction is violent. 

Vanadium chloride, 2 chromium chloride,33 and the combined use of tributylphosphine and diphenyldisulfide34 are also effective in promoting the reductive Nef reaction. 

Impurities with catalytic effects—Impurities that act as catalysts, reducing the activation energy of a process, may increase the rate of reaction significantly, even when present in small quantities. The presence of sulfuric acid, for example, increases the rate of decomposition and decreases the observed onset temperature of various isomers of ni-trobenzoic acid [28]. Also, other substances such as NaCl, FeCl3, platinum, vanadium chloride, and molybdenum chloride show catalytic effects. As a result, the decomposition temperature can be lowered as much as 100°C. Catalysts, such as rust, may also be present inadvertently. Some decomposition reactions are autocatalyzed, which means that one of more of the decomposition products will accelerate the decomposition rate of the original substance. 

Another application of an isomerisation reaction can be found in the production of the third monomer that is used in the production of EPDM rubber, an elastomeric polymerisation product of Ethene, Propene and a Diene using vanadium chloride catalysts. The starting diene is made from vinylnorbomene via an isomerisation reaction using a titanium catalyst. The titanium catalyst is made from tetravalent salts and main group hydride reagents, according to patent literature. 

Vanadium powder, dust, and most of its oxide compounds are explosive when exposed to heat and air. They are also toxic when inhaled. Vanadium chloride compounds are strong irritants to the skin and poisonous when ingested. 

Demet X procedure simply consists of an oxidation at elevated temperature, both the New Demet and the Demet III process has a sulfiding step which transforms the metal oxides to insoluble sulfides. In Demet III the sulfiding step is followed by a partial oxidation step. This oxidation is carefully controlled to produce metal sulfates and sulfides which can be directly removed by washing or be transferred into soluble compounds by the reductive and oxidative washes used in this procedure. In the New Demet process the sulfiding step is followed by chlorination which results in a transformation of the sulfides into washable chlorides. Since vanadium chlorides are volatile, most of the vanadium removal using this procedure occurs in the gas phase. In the Demet X procedure, the vanadium oxides formed are water soluble or can be transformed into water soluble forms by aqueous treatments. In contrast the nickel oxides are insoluble in water. 

Vanadium metal is prepared from pentoxide, V2O5, by reduction with calcium at elevated temperatures. Presence of iodine lowers calcium reduction temperature to 425°C because of heat of formation of calcium iodide. Pentoxide also may be converted to the trichloride, VCI3, and the trichloride reduced with magnesium metal or magnesium-sodium mixture at high temperatures to form high purity ductile metal. Alternatively, a fused mixture of vanadium chloride, sodium chloride, and hthium chloride may be electrolyzed to produce the metal in high purity. 

Lockyer and Baxcndall1 investigated the arc spectrum of vanadium by volatilising vanadium chloride and vanadium oxide between poles of pure silver. Using a Rowland grating, over 650 lines were obtained in the region between A 3887 and A 4932, the more intense of which arc indicated in the following table —... 

It is worth noting here that in contradiction to the data published by Bradley [227] on the formation of VC12(0R)2 alkoxide chlorides on alcoholysis of VC14 his reaction was proved to yield VOCl2 nROH as the major products [607, 1634]. To avoid this reaction, the vanadium chloride should be introduced as an ether solution into the reaction with NaOR for the preparation of vanadium (IV) alkoxides. 

Table VI summarizes important homogeneous Ziegler catalysts. The best known are the systems based on bis(cyclopentadienyl)titanium(IV), titanium alcoholates, vanadium chloride, or chromium acetylacetonate with trialkylaluminum or alkylaluminum halides.

Hydrochloric acid, concentrated, 30.0ml Vanadium chloride, 2.0g Water to make 285.0ml... 

Heat the solution to the boiling point and then add the vanadium chloride. 

VANADIUM BROMIDE see VEKOOO VANADIUM CHLORIDE see VEFOOO VANADIUM(III) CHLORIDE see VEPOOO VANADIUM COMPOUNDS see VCZOOO VANADIUM DUST and FUME (ACGIH) see VDUOOO VANADIUM DUST and FUME (ACGIH) see VDZOOO VANADIUM (OSHA) see VDZOOO VANADIUM OXIDE see VEAOOO VANADIUM(V) OXIDE see VDUOOO VANADIUM OXYTRICHLORIDE see VDPOOO VANADIUM PENTAOXIDE see VDUOOO VANADIUMPENTOXID (GERMAN) see VDUOOO VANADIUM PENTOXIDE (dust) see VDUOOO VANADIUM PENTOXIDE (fume) see VDZOOO... 

The photoreduction of N2 by irradiation of vanadium chloride in aqueous ethanol with u.v. light has been describedAn unstable dinitrogen divanadium complex has been proposed to be the key intermediate and the reaction products include NH3, N2H4, and H2. A model system for N2 reduction involves the photoreduction of acetylene and this can be achieved with a sacrificial bipysRu /Co " system. 

The effect of polymerization conditions on Cp has been studied mainly for two-component systems based on titanium chloride and vanadium chloride . The number of propagation centers changes with the polymerization time proportionally to the reaction rate and is independent of the monomer concentration (0.2-2 mol/1 at 70 °C). Most interesting is the effect of the polymerization temperature on Cp. It has been found that with rising temperature Cp ingreases (Table 3). In the... 

Experimental data on the olefin polymerization proceeding on titanium or vanadium chlorides ... 

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