Olefin epoxidation oxidant advantages

Reviews discuss the advantages of heterogeneous and homogeneous catalytic oxidations for organic synthesis, and catalytic oxygen atom transfer reactions. The new Cr(VI) reagent (51) catalyses the oxidation of secondary alcohols to ketones with peroxyacetic acid. The tetra(diperoxotungsto)-phosphate(3-) anion has been structurally characterised it catalyses stereospecific olefin epoxidations. ... 

Epoxidation. 1,1,3,3-Tetrachloroacetone can mediate the epoxidation of olefins by hydrogen peroxide in the same way as hcxafluoroacctonc (9, 244-245). It has the advantage that it is probably less toxic, and it is inexpensive and commercially available. The actual oxidant presumably is the hydroperoxide 1, which is converted during the epoxidation into the unstable hydrate (2), from which the tctrachloroacetone can be recovered in >70% yield. Monosubstitutcd alkenes are epoxidized in low yields by this method more highly substituted alkenes are epoxidized in 65 85% yield (VPC).1... 

The direct oxidative carboxylation of olefins has great potential, and many advantages. Notably, it does not require the C02 to be free of dioxygen this is an especially attractive feature, as the cost to purify C02 is extremely high, and may discourage its use. Moreover, the direct oxidative carboxylation of olefins can couple two processes-the epoxidation of olefins, and the carbonation of epoxides. Hence, the process makes direct use of those olefins that are available commercially at low price, and which represent an abundant feedstock. Such an approach also avoids having to isolate the epoxide. 

A method for the polymer supported epoxidation of olefins has been reported <05TL1643>. The resin supported phthalate, 11, was oxidized to peracid 12 through oxidation with or a urea-HjOj complex. The reaction was most conveniently carried out by mixing 11, the urea-HPj complex and the olefinic substrate. Simple filtration then provides a wide variety of epoxides in excellent yield. This reagent system provides all of the typical advantages of supported reagents as well as an improved safety profile of the supported peracid. 

In Parton et al., a new type of heterogeneous catalyst was proposed consisting of a solid catalyst (iron phthalocyanine zeolite Y) dispersed in a dense PDMS (polydimethylsiloxane) polymer matrix.[l] The system resulted in strongly increased catalytic activities in the oxidation of cyclohexane.[2] Other systems, such as Mn(bipy)2-Y (mangtuiese bipyridine zeolite Y) were also proven to benefit from such incorporation.[3,4] The results presented here using Ti-MCM-41 confirm this for the epoxidation of olefins, an important route for the production of fine chemicals.[5] The influence of the polymer on the reaction activity and selectivity is shown by using different oxidants and solvent conditions in the epoxidation of 1-octene. It will enable the deduction of the advantages and limitations of the reported membrane occluded catalyst system. 

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