Tungsten compounds

The chemical uses of tungsten have increased substantially in more recent years. Catalysis (qv) of photochemical reactions and newer types of soluble organometaUic complexes for industrially important organic reactions are among the areas of these new applications. 

Various appHcations such as lubricant additives, dyes, pigments, and catalysts are under investigation. Tungsten can be deposited from tungsten hexacarbonyl, but carbide formation and gas-phase nucleation present serious problems (1,2). As a result, tungsten halides are the preferred starting material. 

Direct fluoridation of pure tungsten in a flow system at atmospheric pressure at 350—400°C is the most convenient procedure (4). Tungsten hexafluoride is extremely unstable in the presence of moisture and hydroly2es completely to tungstic acid [7783-03-1]  

Tungsten hexafluoride dissolves in ben2ene or cyclohexane to give a bright red color, in dioxane a pale red, and in ether a violet-brown. 

Tungsten pentafluofide [19357-83-6] prepared by the reduction of the hexafluoride on a hot tungsten filament in almost quantitative yield 

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Reduction to Metal Powder. The metal powder is obtained from APT by stepwise reduction with carbon or hydrogen. The intermediate products are the yeUow oxide, WO blue oxide, (see Tungsten compounds) and brown oxide, WO2. Because carbon introduces impurities,... 

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