1.5.3 Peroxides
Peroxides are important oxidizing agent for the organic compounds. Aqueous H2O2 and t-BuO2H are commonly used hydroperoxides, which are commercially available. The lecture will discuss some of the important oxidation reactions performed with peroxide reagents.
1.5.3.1 Epoxidation of Allylic Alcohols
Epoxidation of allylic alcohols is one of the most important processes in oxidation chemistry. Metal alkoxides with t-BuOOH (TBHP) provide an excellent method for the epoxidation of allylic alcohols (Scheme 1). The double bond selectively undergoes oxidation without affecting the OH group.
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Scheme 1 |
For examples:
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In addition to these homogeneous processes, effort has also been made to develop heterogeneous catalysts for the epoxidation of allylic alcohols with hydroperoxides (Scheme 2). TiO2-SiO2 has been found to be superior to V2O5-SiO2 and MoO3-SiO2 for this purpose. Both TBHP and H2O2 (aqueous and urea H2O2) have been employed as terminal oxidant. These systems also work for the epoxidation of unfunctionalized alkenes.
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Scheme 2 |