Milas reagent

Interestingly, the first examples of catalytic oxygen transfer involved the so-called Milas reagents,4 formed by mixing heterogeneous metal oxide catalysts with a solution of hydrogen peroxide in tert-butanol. These reagents were used for the vicinal hydroxylation of olefins (reaction 10). 

Thus, the Milas reagents may be considered to be the progenitors of the metal catalyst/alkyl hydroperoxide reagents5 5 that were later developed cy, inter alia, Halcon, Arco and Shell workers and culminated in the realization of commercial processes for the epoxidation of propylene (reaction II). These reagents involve the very same metal catalysts, e.g. MoVI, WVI, vv and TiIV, as the Milas reagents and they are mechanistically closely related. 

Since Os04 is volatile, toxic and expensive, considerable effort has been devoted to the catalytic application of the cis dihydroxylation of alkenes in the presence of excess cooxidant.57-290 Previous procedures used metal chlorate (Hoffman reagent),339 or hydrogen peroxide (Milas reagent)350 as cooxidant, usually in Bu OH or acetone.290 Recent procedures utilize t-butyl hydroperoxide in conjunction with ammonium salts (Et4NOH or Et4NOAc)57,351 or N-methylmorpholine N-oxide,352 and are generally more selective. 

Oxidation systems based on osmium have been extensively researched for the hydroxylation of olefins. Hydrogen peroxide/Os04 (Milas reagent) will hydro-... 

Hydrogen peroxide with Milas reagent is also suitable for the cleavage of olefins. The system has been used to prepare aromatic aldehydes such as anisaldehyde from anethole, pipernal from isosafrole and vanilin from iso-eugenol.170,171 Hydrogen peroxide and chromium(III) can be used to cleave methyl methacrylate to methyl pyruvate.172... 

Besides stoichiometric epoxidation and subsequent hydrolysis to diols, metal-catalyzed methods for converting olefins to glycols are also known in the literature. The classical method utilizes hydrogen peroxide in the presence of catalytic amounts of acidic metal oxides (Milas reagents) [2]. Typically, strong oxidants such as osmium [3] and ruthenium tetroxides [4], permanganate [5], and chro-... 

Hydroxylation of polyolefins by Milas reagent can be so arranged that only one double bond is affected e.g., cyclopentadiene gives a mixture of 3-cyclo-pentene-l,2-diol and 4-cyclopentene-l,3-diol.139,143 Another application of this method was the selective oxidation of / -carotene to vitamin-A aldehyde.144... 

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