Vanadium oxovanadium catalyst

Vanadium. A residual oil was desulphurized (673 K, 115 atm) with a non-stoicheiometric vanadium sulphide (S/V, 0.8-1.8) formed in situ from VS4 Vanadium sulphide catalysts have been prepared by in situ sulphiding of vanadium complexes, e.g., bis(acetylacetonato)oxovanadium(IV), dissolved in crude petroleum.Vanadium compounds occurring in heavy oils have been activated as desulphurization and demetallization catalysts by treatment with triethylaluminium. Catalysts consisting of vanadium promoted by nickel can be prepared in situ by deposition of the metals from heavy crude oils. Ni-V hds and hdm catalysts on silica or carbon have been claimed. 

Dynamic kinetic resolution (DKR) of a racemic alcohol with lipase and metal catalysts is often conducted in organic solvents. Since the maximum yield of kinetic resolution of racemic alcohol by lipase is only 50% with 100% ee, metal catalysts to racemize the unreactive enantiomer substrate is necessary to achieve 100% yield and 100% ee [22]. For example, mthenium catalysts have been widely used for this process as shown in Figure 3.12a [22b]. Vanadium has also been used, and to improve both catalytic activity and compatibility of the oxovanadium catalysts with the lipases, a novel oxovanadium catalyst (V-MPS) immobilized inside mesoporous silica (MPS) with pores of approximately 3 nm in diameter was prepared. With this immobilization preparation, a complete division of the racemization site and the enzymatic reaction site was achieved. 

Oxovanadium(V) and oxomolybdenum(VI) were incorporated into crosslinked polystyrene resins functionalized with iminodiacetic acid or diethylenetriamine derivatives 921 The polymer complexes were used as catalysts in the oxidation of olefins with f-butylhydroperoxide. Vanadium(V) complexes promote the epoxidation of allylic alcohols in a highly regioselective manner, e.g., 2,3-epoxide was obtained in 98 % selectivity from e-geraniol at 80 °C. The catalytic activity of the vanadium(V) complexes is generally higher than that of the molybdenium(VI) complexes in the oxidation of allylic alcohols, whereas an opposed trend holds for the epoxidation of cyclohexene. 

Oxovanadium phosphate VOPO4.2H2O is used as a catalyst, or catalyst precursor. It is a layered compound in which six oxygen atoms around the vanadium form an almost regular octahedron. The weaker interlayer binding makes VOPO4.H2O and its analogs attractive as potential hosts for coordination—intercalation reactions [5—11]. 

The reaction of di- -butylsulfide with r-butyl hydroperoxide proceeds at a convenient rate in ethanol at 25 °C in the presence of catalytic quantities of bisacetyl-acetonato-oxovanadium(IV) [VO(acac)2] affording di-n-butylsulfoxide in quantitative yield [146]. The kinetics of this reaction have been examined in detail. With [r-BuOOH]o/[VO(acac)2] >8 and [VO(acac)2]o = 1 x 10 to 2 x 10 M the reaction is first order in sulfide and first order in vanadium catalyst, equation (97). 

Molybdenum and vanadium compovmds have also been widely investigated as catalysts for the oxidation of alcohols with tert-butyl hydroperoxide (TBHP) as the oxidant. With the former a peroxometal pathway is involved while with the latter an oxovanadium(V) intermediate is the active oxidant. As with the H202-based systems described above, these systems exhibit a preference for the oxidation of secondary hydroxyl functionalities over primary ones. In contrast, zirconyl acetate, SO(OAc)2, catalyzes the selective oxidation of primary alcohol moieties with TBHP (Reaction 29) °". ... 

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