Enantioselective Friedel-Crafts reaction catalysed by alginate aerogels

Laouadi, Ornella Laura Nathalie (2019) Enantioselective Friedel-Crafts reaction catalysed by alginate aerogels. [Laurea magistrale], Università di Bologna, Corso di Studio in Chimica industriale [LM-DM270]
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Alginates are polysaccharides derived from brown algae, available in nearly unlimited amounts at very low prices. In the presence of some divalent metals, these renewable biopolymers can readily form hydrogels, solvogels and aerogels, characterized by high surface areas, good mechanical properties, tolerance to different media, and easy manageability. For these reasons, alginates are nowadays being thoroughly studied in heterogeneous catalysis; several applications in supported metal catalysis and as heterogeneous Brønsted acids have emerged. However, none of these studies has given an answer to the following intriguing question: can we use the intrinsic chirality of alginates to induce enantioselectivity in a chemical reaction? In order to answer this question a representative reaction, the Friedel-Crafts alkylation of nitroalkenes with indoles, was tested in this master thesis. This study, which involved a large screening of a variety of alginate gels under different reaction conditions, showed that Cu2+ and Ba2+ are the best cross-linking metals to promote the Friedel-Crafts reaction. Indeed, good activity with moderate enantiomeric excesses were obtained under the optimized reaction conditions. Furthermore, these two metals allowed the access to both enantiomers of the products, an important aspect given that only one enantiomeric form of alginates is available. Finally, the heterogeneous nature of the catalysis by one of the two gels was proved, and a good recyclability was demonstrated, by showing that the same catalyst can be used at least five times with similar results.

Tipologia del documento
Tesi di laurea (Laurea magistrale)
Autore della tesi
Laouadi, Ornella Laura Nathalie
Relatore della tesi
Correlatore della tesi
Corso di studio
Advanced Spectroscopy in Chemistry
Ordinamento Cds
Parole chiave
heterogeneous catalysis metal catalysis alginates biopolymers polysaccharides aerogels Friedel-Crafts alkylation chirality enantioselectivity asymmetric synthesis
Data di discussione della Tesi
26 Luglio 2019

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