Magnetic nanoparticles as a versatile platform for catalytic applications

Identificador:  TDX:2451

Handle: https://hdl.handle.net/20.500.11797/TDX2451

Autors:  Ranjbar Rizi, Sara

Resum:
This thesis has focused on the use of magnetic nanoparticles (MNPs) in catalysis. These allow a facile recovery of the catalyst after the reaction, thus making them an interesting tool to be used in large scale processes. In addition, modifying the surface of nanoparticles with different linkers gave us the opportunity to anchor a variety of organocatalysts, giving rise to MNP-based catalytic materials. In the first project, two new hybrid materials based on carrageenan and MNPs were developed and tested in the Michael addition of aldehydes to nitroalkenes. The first one, a combination of carrageenan and MNPs showed good results in this reaction while the individual components were inactive. The second catalyst, which included an analog of the Jørgensen-Hayashi catalyst, also showed good activity and gave excellent ee’s. In the second project, an analog of the second generation MacMillan catalyst was immobilized onto Fe3O4 NPs and polystyrene. The resulting catalysts were applied to the asymmetric Friedel-Crafts alkylation of indoles with α,β-unsaturated aldehydes. In this study, the polystyrene-based catalyst showed higher stability and provided better stereoselectivities. The last project has focused on the use of carbon-coated cobalt magnetic nanoparticles (Co/CNPs) in catalysis. Thus, another hybrid material was developed based on microporous organic polymers (MOPs) encapsulated with Pd nanoparticles and Co/CNPs. To build up the polymer, different substrates such as toluene, aniline and phenol were used. After synthesizing Pd nanoparticles inside the pores of the polymer, these catalysts were applied to the hydrogenation and Suzuki cross-coupling reactions. Despite giving from good to moderate yields, these catalysts suffer from leaching of Pd, so further research is required.