Direct oxidative esterification of primary alcohols and oxidation of secondary alcohols over mesoporous spherical silica encapsulated MnO2 nanoparticles

Abstract

In this work, a simple and efficient strategy for the fabrication of novel encapsulated MnO₂ nanoparticles inside spherical mesoporous silica hollow-nanoparticles was described. They were synthesized by consecutively anchoring MnO₂ nanoparticles on poly(styrene-co-methacrylic acid) particles, coating with a mesoporous silica shell, and subsequently removing the polymeric core by dissolving in acetone. The catalytic activity of the nanoparticles was examined in the aerobic oxidation of various primary and secondary alcohols, which showed good activity and selectivity for the transformation of primary alcohols to the corresponding esters through the oxidative esterification process and secondary alcohols to ketones in short reaction times under mild reaction conditions. In addition, the catalyst system was utilized for the oxidation of primary alcohols to aldehydes using tert-butyl hydroperoxide (TBHP) as an oxidant under mild conditions and produced an excellent product yield.