Study of the activity and enantioselectivity of alginate-based catalysts in Michael addition reactions

This thesis, resulting from an internship work performed at a research laboratory of the Department of Industrial Chemistry “Toso Montanari” of the University of Bologna, describes a study on the activity and enantioselectivity of various metal-alginate gel beads as heterogeneous catalysts for some representative reactions. Alginates are a class of biopolymers extracted from brown algae, which can be considered as a cheap and renewable biopolymer. For the preparation of the catalysts, we followed typical preparation protocols, delivering a small library of alginate gel beads featuring different cross-linking metals. These catalysts were tested in two Michael addition reactions, using three representative solvents. Promising results were obtained in the addition of diethyl malonate to nitrostyrene, where relatively higher rates were observed for alginate containing alkaline earth metals, compared to first-row transition metals or alginic acid. A possible explanation could be made considering the mechanism of the reaction, where the alkaline environment provided by the alkaline earth metal-based material can promote the reaction.