Oxidation of olefins using atmospheric oxygen atoms initiated by tert-butylhydroperoxide or hydrogen peroxide with silver nanoparticles deposited on MCM-41 as catalysts

Abstract

Silver nanosized particles were grown on the surface and in the channels of mesoporous silica (MCM-41) by stirring a mixture of AgNO₃ and polyvinylpyrrolidone (PVP) in ethylene glycol in a 1 : 20 weight ratio with MCM-41 for 1 h. The heterogeneous product was analysed by BET surface area and X-ray powder diffraction measurements, as well as TEM images which indicated that 5 to 20 nm sized Ag particles were on the surface of MCM-41. The dried material, suspended in a mixture of 1,2-dichloroethane and acetonitrile and in the presence of ^tBuOOH held at 80 °C for 24 h, was capable of the oxidation of the olefins (Z)-cyclooctene, cyclohexene, styrene and indene resulting in a variety of oxidized products. Comparable oxidation was also accomplished in a green solvent mixture consisting of 3% NaCl dissolved in H₂O and ^tBuOH (1 : 1 by volume). The catalyst was active for five sequential cycles. After the first cycle, H₂O₂ instead of ^tBuOOH could be used as the radical initiator as the Ag nanoparticles were passivated by the formation of AgCl on the surface. This research illustrates a method of oxygen activation allowing for the transfer of an oxygen atom from the atmosphere onto an olefin, presumably via the formation of a peroxide radical.