Hydroperoxides, from alkenes, with hydrogen

Sulfides react faster with hydrogen peroxide and alkyl hydroperoxides than do alkenes. For this reason, transition metal catalysts are rarely necessary, but these reactions are acid catalyzed and first order in both sulfide and peroxide. The acid (HX) can be as weak as alcohol or water but the "effectiveness (of the oxidation) is determined by the pXa of the acid. Sulfides also react faster with peroxides than do ketones (see the Baeyer-Villiger reaction, sec. 3.6). Formation of the sulfone in these reactions is straightforward, but requires more vigorous reaction conditions. It is usually easy to isolate the sulfoxide from oxidation of a sulfide. Direct conversion of a sulfide to a sulfone requires excess peroxide and vigorous reaction conditions (heating, long reaction times, more concentrated peroxide). 

Oxirans.— Epoxides are readily available from the catalytic oxidation of alkenes with 2-hydroperoxyhexafluoropropan-2-ol (HPHI) (1), which itself is easily prepared from hexafluoroacetone hydrate (2) and hydrogen peroxide (Scheme 1). HPHI is claimed to have similarities to the natural flavin hydroperoxides which are implicated in epoxidations and hydroxylations by external flavoprotein mono-oxygenases. Yields are typically in the range 77—92%. 

In the propagation steps, this radical then reacts with oxygen, producing a peroxyl radical, which then abstracts hydrogen from a further molecule of the substrate. The product is thus the hydroperoxide, reaction having occurred at the allylic position of the alkene. Two possible chain-termination steps might... 

Literature procedures for the synthesis of hydroperoxides include the preparation from hydrogen peroxide (via reaction with alkyl halides, -phosphites, -suEonates, alkenes. 

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