Amine-functionalized ionic liquid-based mesoporous organosilica as a highly efficient nanocatalyst for the Knoevenagel condensation

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Abstract

A novel aminopropyl-containing ionic liquid-based mesoporous organosilica was prepared and characterized and its catalytic performance was studied in the Knoevenagel condensation.

Abstract

A novel amine-functionalized ionic liquid-based periodic mesoporous organosilica (PMO-IL-NH ₂) was prepared and characterized and its catalytic performance was investigated in the Knoevenagel reaction. PMO-IL-NH ₂ was prepared by simultaneous co-condensation of 3-aminopropyltrimethoxysilane, an ionic liquid and tetramethoxysilane in the presence of a surfactant template under acidic conditions. The material was characterized by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, thermal gravimetric analysis (TGA), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalytic application of PMO-IL-NH ₂ was then successfully carried out in the Knoevenagel condensation of a variety of different aldehydes with ethyl cyanoacetate under solvent-free conditions at room temperature, giving high to excellent yields of the corresponding products. The catalyst was also recovered and reused several times without a significant decrease in either activity or product selectivity. The TEM image and nitrogen sorption analysis of the recovered catalyst after the fifth reaction cycle confirmed its high stability and durability under the applied reaction conditions.

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Silica-based mesoporous organic-inorganic hybrid materials.

Frank Hoffmann, Maximilian Cornelius, Jürgen Morell … (2006)

Mesoporous organic-inorganic hybrid materials, a new class of materials characterized by large specific surface areas and pore sizes between 2 and 15 nm, have been obtained through the coupling of inorganic and organic components by template synthesis. The incorporation of functionalities can be achieved in three ways: by subsequent attachment of organic components onto a pure silica matrix (grafting), by simultaneous reaction of condensable inorganic silica species and silylated organic compounds (co-condensation, one-pot synthesis), and by the use of bissilylated organic precursors that lead to periodic mesoporous organosilicas (PMOs). This Review gives an overview of the preparation, properties, and potential applications of these materials in the areas of catalysis, sorption, chromatography, and the construction of systems for controlled release of active compounds, as well as molecular switches, with the main focus being on PMOs.