Rhenium(VII) oxide
Rheniumheptaoxid
Yellow, almost odorless solid
Fixed
6 g · cm -3
220 ° C
363 ° C
- Decomposition in water
- At room temperature, soluble in alcohols, ethers, amines, dimethylsulfoxide, nitromethane, benzene, and carbon tetrachloride
Risk
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Rhenium (VII ) oxide Re.sub.2O.sub.7 is a chemical compound and is one of the oxides of rhenium. There is a yellow hygroscopic solid. Compared to unstable and explosive manganese (VII ) oxide, rhenium (VII ) oxide, much more stable.
Production and representation
Rhenium (VII ) oxide is obtained by heating rhenium or rhenium compounds in air.
Properties
Physical Properties
Rhenium (VII ) oxide crystallizes in an orthorhombic crystal structure with space group P212121. The lattice constants are a = 125 pm, b = 152 pm and c = 54 pm. The crystal forms of rhenium (VII ) oxide ReO4 tetrahedra and octahedra ReO6, which alternate with each other and are linked via the corners.
Chemical Properties
Rhenium (VII ) oxide is very hygroscopic and readily soluble in water. When loosening the strong acid perrhenic forms. Rhenium (VII ) oxide is reduced by hydrogen at 300 ° C to rhenium ( IV) oxide.
Use
Rhenium (VII ) oxide is an intermediate in the production of elemental rhenium. It is produced during roasting of rhenium- manganese ores. Rhenium (VII ) oxide is achieved after the separation of fly ash remaining in the water. From perrhenic acid thereby resulting rhenium is precipitated as ammonium perrhenate, and reducing with hydrogen to the element.
Rhenium (VII ) oxide can be used as a catalyst in various reactions of organic chemistry. As can be converted with the aid of rhenium (VII ) oxide alkanes to carboxylic acids. Further by rhenium (VII ) oxide catalyzed reactions are metathesis reactions of olefins. Of rhenium (VII ) oxide, the catalyst may be recovered methyltrioxorhenium (MTO).