Oxidation with Hydrogen Peroxide and a Catalyst

A fair number of articles have recently dealt with the kinetics and mechanism of the reaction.It has been utilized among others for the stereospecific production of an antibiotic. The method is of great promise in industrial synthe-ses it has the advantage that the side-product of the reaction is water. 

Molybdenum -peroxo complexes give oxiranes in high yields. For anhydrous hydrogen peroxide, a three-step mechanism is assumed, with an a-hydroxyhydroperoxide intermediate. Detailed studies have been made on the mechanism of the reaction of the MoO(02)2-HMPT complex with olefins (Eq. 27). 2  

The experimental results have led to the proposal of a 1,3-dipolar addition mechanism, the molybdenum atom being involved directly (Eq. 28). 

The structure and decomposition of the peroxomolybdenum-olefin complex have been investigated. Further kinetic studies suggest the structure of the transition complex shown in Eq. 29. The double bond is attacked by a positively charged oxygen.labeling has demonstrated that the oxo oxygen is not affected in the reaction. A -Steroids are oxidized with surprising stereospecificity this is evidence in favor of the 1,3-dipolar mechanism.  

Epoxidation of olefins with hydrogen peroxide in the presence of Fe(acac)3 has been examined in the cases of stilbene, unsaturated alcohols, and fatty acids. From cis- and trans-olefins the main product is the trans isomer, formed via a biradical intermediate. Cholesterol undergoes /3-epoxidation.  

---