DESIGN AND DEVELOPMENT OF HETEROGENEOUS CATALYSTS FOR CHEMO- AND REGIOSELECTIVE OXIDATIONS USING SUSTAINABLE OXIDANTS (H2O2, O2)

Epoxidation of alkenes is a reaction of a great interest since epoxides are versatile and useful intermediates in fine chemical synthesis. However, nowadays, in the epoxidation of alkenes, hazardous oxidants are still commonly employed. This is the reason why the development of new epoxidation methods which employ safer oxidants and produce little waste are greatly requested. The present PhD thesis is mainly focused on the design and development of efficient and robust heterogeneous catalysts for epoxidation reactions using TBHP, H2O2 or, in the best case, molecular O2 or air as oxidants. The work is divided into six parts. In all topics the major attention is paid on the design and development of heterogeneous catalyst for the epoxidation reactions. Ti(IV)-heterogeneous silicas were successfully synthesized by the grafting procedure. It was found that all catalysts are active in epoxidation reactions with aq. H2O2 thanks to the applied slow dropwise addition protocol. Moreover, the effect of Ti modification surrounding on the catalytic performance was studied. Also the synthesis of the model compound (Ti-POSS/SiO2) was carried out. This model can be a powerful tool for studying the mechanism of the epoxidation reaction. The last two parts of the manuscript are focused on the in situ H2O2 production by means of GOx or Au-nanoparticles. For this, the encapsulation of GOx was carried out and it’s combined use with Ti(IV)-silica catalysts was tested in the oxidation reactions both in aqueous and organic media. Activation of molecular O2 by means of Au-nanoparticles was also studied. The effect of various factors, such as the role of Au nanoparticles’ size, the solvent’s nature or the pH during the catalyst preparation, was studied.