Mekanokemisk syntes av metall organiska ramverk för katalytiska väteutlåningsreaktioner

Abstract

Metal-organic frameworks are porous coordination polymers with high specific surface area and flexibility upon functionalisation, which makes them interes ting for heterogeneous catalysis. In this study, metal-organic frameworks were synthesised mechanochemically and subsequently evaluated for their catalytic ac tivity in borrowing hydrogen reaction for N-alkylation of aniline with benzyl alcohol. Mechanochemical synthesis was performed on five metal-organic frameworks, NH2-MIL-88(Fe), NH2-MIL-125(Ti), MIL-100(Fe), Zr-MOF-818, and Cu-MOF-74. They were then characterised using powder diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and gas adsorption to investigate structure, crystallinity, and thermal stability. The results showed that only NH2-MIL-88(Fe) and NH2-MIL-125(Ti) were successfully synthesized. They were then tested for their activity in borrowing hydrogen reactions, also called hydrogen autotransfer reactions, and the reaction mixtures were subsequently analysed with nuclear magnetic resonance spectroscopy. Both frameworks presented catalytic activity, however NH2-MIL-88(Fe) showed the best result under the investigated reaction conditions. Furthermore, the reaction outcome improved with extended reaction time and the addition of a base. The project concludes that mechanochemical synthesis is one possible met hod for producing metal-organic frameworks, but the method entails restrictions with crystallinity and reproducibility. The results show that these materials possess catalytic activity and therefore be suited for borrowing hydrogen reactions.