Catalysis with solid lipid particles

We describe the preparation of catalytic solid lipid particles as a new heterogeneous catalytic system. This system was constructed by incorporating polyethyleneimine modified with oleic acid (PEI-C₁₈) within solid lipid particles (SLPs) coated with a silica shell. The hot sonication technique was employed to emulsify the oil phase containing paraffin wax, PEI-C₁₈, and tetraethyl orthosilicate (TEOS) in aqueous surfactant solution generating oil-in-water emulsion, followed by interfacial polymerization of TEOS in basic medium producing silica shell via the sol–gel route. The reactivity of catalyst PEI-C₁₈ encapsulated within SLPs@SiO₂ was tested in Knoevenagel condensation as a model reaction. This new catalyst showed high catalytic efficiency in the condensation of aromatic aldehydes with various active hydrogen compounds forming α,β-unsaturated compounds, while triple distilled water was utilized as a reaction medium. The catalyst was easily isolated from the reaction mixture using centrifuge technique and recycled over 5 times without any significant loss in its catalytic activity.