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The olefin metathesis is the other reaction for which rhenium is used as catalyst. Normally Re 2 O 7 on alumina is used for this process. [73] Rhenium catalysts are very resistant to chemical poisoning from nitrogen, sulfur and phosphorus, and so are used in certain kinds of hydrogenation reactions. [23] [74] [75]
Rhenium(VI) oxide has an appearance similar to that of copper. Rhenium(IV) oxide (or rhenium dioxide) is an oxide of rhenium, with the formula ReO 2. This gray to black crystalline solid is a laboratory reagent that can be used as a catalyst. It adopts the rutile structure. It forms via comproportionation: [4] 2 Re 2 O 7 + 3 Re → 7 ReO 2
Reaction scheme of the olefin metathesis – changing groups are colored. In organic chemistry, olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds.
Perrhenic acid is a precursor to a variety of homogeneous catalysts, some of which are promising in niche applications that can justify the high cost of rhenium. In combination with tertiary arsines, perrhenic acid gives a catalyst for the epoxidation of alkenes with hydrogen peroxide. [8] Perrhenic acid catalyses the dehydration of oximes to ...
Methylrhenium trioxide is commercially available. It can be prepared by many routes, a typical method is the reaction of rhenium heptoxide and tetramethyltin: [1] Re 2 O 7 + (CH 3) 4 Sn → CH 3 ReO 3 + (CH 3) 3 Sn−O−ReO 3. Analogous alkyl and aryl derivatives are known.
The thiourea hydrogen bonds to the nitro group and stabilizes the incoming negative charge, while the amine acts a specific base to activate the nucleophile. This is an example of bifunctional catalysis. Hydrogen-bond catalysis is a type of organocatalysis that relies on use of hydrogen bonding interactions to accelerate and control organic ...
Rhenium(IV) oxide or rhenium dioxide is the inorganic compound with the formula ReO 2. This gray to black crystalline solid is a laboratory reagent that can be used as a catalyst . It adopts the rutile structure.
Rhenium(VII) sulfide is a chemical compound with the formula Re 2 S 7. It has a complex structure, but can be synthesized from direct combination of the elements: [ 1 ] 2 Re + 7 S → Δ Re 2 S 7 {\displaystyle {\ce {2Re{}+7S->[{} \atop \Delta ]Re2S7}}} Alternatively, rhenium(VII) oxide reacts with hydrogen sulfide in 4N HCl to the same end ...