Optimització de sistemes basats en nanopartícules de sílice per a la catàlisi heterogènia d’acoblament d’alcohols

Abstract

In this final degree project, ruthenium complexes based on polypyridyl and dmso ligands have been synthesized and characterized, with the aim of evaluating their catalytic activity in the coupling of alcohols and the possibility of anchoring silica nanoparticles in these types of complexes in order to optimize the system. These compounds have been obtained from a first synthesis of the compound [RuCl2(dmso)4, [1], from the reagent RuCl3·3H2O and dimethylsulfoxide at reflux. Once this complex has been obtained, a second synthesis is carried out where the 2,2':6',6"-terpyridine ligand is coordinated to the compound [1] in chloroform at 80oC, to end up forming cis-[RuCl2(terpy)(dmso), [2]. In order to study and characterize the properties of the synthesized compounds, spectroscopic (NMR, UV-vis), spectrometric (ESI-MS) and electrochemical (cyclic voltammetry) techniques have been used. On the other hand, in this work, studies have been carried out focused on the incorporation of the compounds into different silica materials (ST, LUS-TMA o-Ph-ST and Ph@LUS), some of them, of the nanoparticle type, with the aim of making the catalytic system more efficient. As in the previous study, spectroscopic (NMR, UV-vis), spectrometric (ESI-MS) and electrochemical (cyclic voltammetry) techniques have been used to to characterize the new materials generated. In addition, the catalytic efficiency of the complexes has been evaluated in the coupling of benzyl alcohol and 1-phenylethanol in homogeneous phase, using several bases (potassium hydroxide, potassium carbonate, piperidine and sodium methoxide) to improve selectivity and conversion. Of these bases, the most suitable has been sodium methoxide. Additionally, the coupling product has been quantified by gas chromatography using biphenyl as an internal standard, and the percentage of conversion and selectivity of the different complexes have been calculated to be able to compare the catalytic activity of the complexes in catalysis. The catalytic activity of the heterogeneous systems obtained from anchoring the catalysts on silica-type supports has also been studied, but the activity obtained has been low. At the end of the work, future strategies are proposed to improve the efficiency of heterogeneous catalysts

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