Oxygenation, superacid-catalyzed

The superacid-catalyzed electrophile oxygenation of saturated hydrocarbons, including methane with hydrogen peroxide (via H302 ) or ozone (via HOs ), allowed the efficient preparation of oxygenated derivatives. 

Because the protonation of ozone removes its dipolar nature, the electrophilic chemistry of HOs, a very efficient oxygenating electrophile, has no relevance to conventional ozone chemistry. The superacid-catalyzed reaction of isobutane with ozone giving acetone and methyl alcohol, the aliphatic equivalent of the industrially significant Hock-reaction of cumene, is illustrative. 

Similar oxygen stabilized ethylene dications were proposed in several types of superacid-catalyzed condensation reactions involving 1,2-dicarbonyl compounds. For example, 2,3-butanedione condenses in high yield with benzene and the superelectrophile (35) is considered to be the key intermediate, because the monoprotonated species (78) is not sufficiently electrophilic to react with benzene (eq 17).35 Several biologically important a-ketoacids were also found to generate superelectrophiles... 

For skeletal rearrangements over zeolite, the nonclassical protonated cyclopropane intermediate could account for the experimental observations. Theoretical studies of the reaction mechanism indicated that protonated cyclopropane-type species do not appear as intermediates but rather as transition states. Considering all zeolite-catalyzed hydrocarbon reactions (hydride transfer, alkylation, disproportionation, dehydrogenation), only carbocations in which the positive charge is delocalized or sterically inaccessible to framework oxygens can exist as free reaction intermediates. In theoretical studies on the mechanism of the superacid-catalyzed isomerization of n-alkanes (ab initio and DFT calculations), protonated cyclopropanes were found to be transition states for the branching of both the 2-butyl cation and the 2-pentyl cation. ... 

Baeyer-Villiger oxidation of several ketones with hydrogen peroxide-Magic Acid systems . In the superacid-catalyzed hydroxylation of straight-chain alkanes such as ethane, propane, butane, etc. with hydrogen peroxide, related oxygenated products were identified . ... 

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