Preparation, characterization and use of hybrid heterogeneous catalysts supported on silica or magnetic nanoparticles for eco-efficient processes

Abstract

In this PhD thesis we present a work about synthesis, characterization and use of heterogeneous catalysts for green processes. We examined a silica supported decatungstate for selective oxidation of alcohols and epoxidation of cis-cyclooctene. We tested its reactivity in green synthesis and the recyclability. Also we examined the anchorage of the polyoxoanion decatungstate on magnetite nanoparticles in order to obtain a magnetic heterogeneous catalyst recoverable with simple magnetic decantation and immediately reusable. We present the synthesis of an heterogeneous catalyst for oxidation of hydroquinones to abtain the corresponding quinones with a decatungstate anchored to magnetic nanoparticles with tetraalkyl phosphonium as counter ion. We obtain a selective and reactive catalyst obtaining excellent yields and selectivity in short time, and the catalyst was simple recoverable and reusable. We examined the anchorage of chiral complex on silica for obtain a heterogeheous catalyst for enantioselective oxidation of sulfides to the corresponding sulfoxides. The catalyst was able to oxide the sulfides with good yields and selectivity but with modest enantiomeric excess. In collaboration with prof. Seddon group we anchorage a basic ionic liquid on silica for obtain a heterogeneous catalyst for coniugate addition of nitroalkanes to electronwithdrawing olefins in order to obtain γ-nitroketones, and also we studied the application of this catalyst in synthesis of 4-H-pyrans. The synthetized catalyst shown good reactivity and perfect recyclability in the two studied reactions. During the PhD, in collaboration with prof. Seddon group, in QUILL centre of Belfast University we synthetize and use a new basic ionic liquid, with two basic function, obtaining a catalyst for a one-pot synthesis obtaining interesting multifunctional product. The catalyst showed excellent reactivity obtaining the target products in excellent yields and selectivity.