Tungsten Hexafluoride

Introduction

Name: Tungsten(VI) Chloride
Other Name: Tungsten Hexachloride
CAS: 13283-01-7
MDL: MFCD00011463
Formula: WCl₆
Molecular weight：396.56
Density(g/mL,25℃):3.52
Melting Point(ºC): 275
Boiling Point(ºC,Atmospheric Pressure):346

Nature

Tungsten hexafluoride is a crystal with dark blue or blue-purple, which soluble in carbon disulfide, but insoluble in ether, ethanol, benzene, carbon tetrachloride. It is easily decomposed in hot water. It will be oxidized to WOC_l4, WO₂C_l2 or tungsten oxide in the air when heated. Tungsten hexafluoride which contains tungsten oxychloride is easily decomposed by water vapor. Tungsten hexafluoride will be reduced by hydrogen under high temperature, and then tungsten powder separated out.

Preparation

1. Tungsten hexafluoride can be prepared by metal tungsten powder and dried chlorine gas at 500~600℃; it is used for vapor deposition of tungsten plating, and the preparation of single crystal tungsten wire, conductive layer on the glass surface and olefin polymerization catalyst.

2. Put the 100g of tungsten trioxide and 1L of hexachloropropane into a round bottom flask with capacity of 2L, reflux condenser with drying tube, heated with thorough stirring until tungsten trioxide completely reacted and dissolved, by the way, it takes about 4h. Generate a black crystal after cooling down, then filtered off and washed the crystals with dry carbon tetrachloride in a dry box; exhausting by a vacuum pump with trap for over 1h to remove all of the organic solvent. The product should be sealed. Also, vanadium trichloride, niobium pentachloride and molybdenum pentachloride can be synthesizing by the same way.

3. Tungsten metal powder is put into a quartz reaction tube, carry out a reaction at 1000℃ by the time chlorine gas inletting, and then the target product sublimated and precipitated in the cold site of the tube. It is extremely important that inlet an inert gas for completely replacing the air and chlorine inside the receiver before and after the reaction. When mixed with oxygen or moisture, it is easy to generate chlorine tungsten oxide WOC_l4 (red, melting point 21℃, boiling point 228℃) and WO₂C_l2 (yellow, melting point 266℃) and other items. If the target product mixed with the above-products, they can be removed by heating because of its more volatile than tungsten hexafluoride. However, when the temperature is higher than the boiling point (346℃), it would cause decomposition of the target product. If the raw material is pure and not oxygen or moisture mixed, then the resulting finished product is very pure.

Ecological Data

Primary irritant effect:
On the skin: May cause irritation
On the eyes: May cause irritation
Sensitization: No known sensitizing phenomenon.

Tungsten hexafluoride is extremely harmful to water, it should not reach ground water, water course or sewage system even though a small amount; without government permission, none of this material is allowed to release to the environment.

Storage

Tungsten hexafluoride is suggested to store in a closed, cool and dry condition at room temperature.