Rhenium heptaselenide

Catalytic hydrogenation of thiophene poses a problem since noble metal catalysts are poisoned, and Raney nickel causes desulfurization. Best catalysts proved to be cobalt polysulfide [425], dicobalt octacarbonyl [426], rhenium heptasulfide [5i] and rhenium heptaselenide [54]. The last two require high temperatures (230-260°, 250°) and high pressures (140, 322 atm) and give 70% and 100% of tetrahydrothiophene (thiophane, thiolene), respectively. 

Thiophene was also hydrogenated to tetrahydrothiophene over rhenium heptasulfide (Re2S7) at 230-260°C246 or rhenium heptaselenide (Re2Se7) at 250°C and at pressures greater than 30 MPa H2 (eq. 12.129),247 without accompanying hydrogenolysis of the carbon-sulfur bond that occurred extensively over molybdenum sulfide.246... 

Rhenium heptaselenide, Re SeT. Broadbent and Whittle describe the preparation of this hydrogenation catalyst and report that it is more reactive in the reduction of 0=0 than of 0=C (unless conjugated). It does not effect hydrogenolysis of the C—S link. 

Rhenium heptaselenide, hydrogenations with — 15, 57 Rhenium heptoxide, hydrogenations with — 15, 83 Rhodanides s. Thiocyanates Rhodanines... 

Rhenium heptaselenide Amines from nitro compounds... 

The same is true of rhenium catalysts rhenium heptoxide [42], rhenium heptasulfide [5i] and rhenimn heptaselenide [54] all require temperatures of 100-300° and pressures of 100-300 atm. Rhenium heptasulfide is not sensitive to sulfur, and is more active than molybdenum and cobalt sulfides in hydrogenating oxygen-containing functions [55,55]. 

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