Alkenes oxidation molybdenum catalyzed

The molybdenum-catalyzed oxidation of alkynes by /-butyl hydroperoxide has been investigated 73JCS(P1)2851) (the epoxidation of alkenes by this system has become an important reaction Section 5.05.4.2.2(i)) but the formation of oxirenes was excluded. 

The molybdenum-catalyzed conversion of alkenes into epoxides by alkyl hydroperoxides is an important commercial process.17,18 The synthetic potential of such reactions in regard to more complex organic molecules has been evaluated19 alkyl hydroperoxides are used as oxidants in the... 

Further examples of molybdenum-catalyzed asymmetric epoxidations of simple alkenes have been reported by Otsuka and co-workers21 who described a reagent derived from tert-butyl hydroperoxide, chelated with molybdenum oxide and (-f)-diisopropyl tartrate. 

Scheme 4.7-15 Molybdenum-catalyzed oxidation of alkenes using TBHP as the oxidant in SCCO2 [15,76,78].

Olefin metathesis is the transition-metal-catalyzed inter- or intramolecular exchange of alkylidene units of alkenes. The metathesis of propene is the most simple example in the presence of a suitable catalyst, an equilibrium mixture of ethene, 2-butene, and unreacted propene is obtained (Eq. 1). This example illustrates one of the most important features of olefin metathesis its reversibility. The metathesis of propene was the first technical process exploiting the olefin metathesis reaction. It is known as the Phillips triolefin process and was run from 1966 till 1972 for the production of 2-butene (feedstock propene) and from 1985 for the production of propene (feedstock ethene and 2-butene, which is nowadays obtained by dimerization of ethene). Typical catalysts are oxides of tungsten, molybdenum or rhenium supported on silica or alumina [ 1 ]. 

A mixed-valent polymolybdate on active carbon was prepared from molybdenum metal and H202, followed by the addition of active carbon to the aqueous solution [114,115], This catalyzed the epoxidation of several alkenes in 2-propanol using H202 as an oxidant, while the efficiency of H202 utilization was very low (< 25%). The epoxidation likely proceeded mainly on the surface of the catalyst because the recovered catalyst showed almost similar catalytic activity. 

The epoxidation of petrochemical alkenes is an intensely investigated oxidation reaction and in recent years numerous homogeneous catalysts have been developed for this reaction. However, so far the catalytic epoxidation of fatty compounds has been investigated only marginally. Sobczak and Ziolkowski reported on the epoxidation of oleic acid with organic hydroperoxides catalyzed by molybdenum complexes [37]. Typical homogeneous catalysts include Mo(CO)6 and Mo02(acac)2. 

Haas, G. and Kolis, J. (1998). Oxidation of alkenes in snpercritical carbon dioxide catalyzed by molybdenum hexacarbonyl, Organometallics, 17, pp. 4454-4460. 

Another facet of surface organometallic chemistry involves modelling of the mechanisms of surface reactions on the basis of the reactivity of molecular models. For example, the reactivity of metal-imine complexes of molybdenum is considered by CHAN, who proposes elementary steps constituting the catalytic cycle of the surface-catalyzed alkene ammoxidation reaction, which is of great industrial importance. HERRMANN provides some very fine examples of molecular models of the rhenium oxide catalysts used commercially in the alkene metathesis reaction. 

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