Hydrosilylation Reactions Catalyzed by Novel Metalloporphyrin Catalysts Intercalated Inside Clay Nano- and Micro-Particles

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Waseem Wajeeh Sa'id Mansour

Research is active to find ways to combine advantages of both homogeneous and heterogeneous catalysts together, by supporting the homogeneous catalysts onto insoluble supports. Such a technique would yield a new catalyst system that is highly active (as homogeneous system) and easy to recover (as heterogeneous system). This work describes how homogeneous catalysts, such as metalloporphyrins, can be intercalated into micro- and nano-scale clay particles such as Montmorillonite and Biotite to produce a new type of supported catalyst system [MnIII(Tpyp)]+(SO4)1/2/nano- and micro-clay. Routes to achieve metalloporphyrin intercalation between layers are discussed. These new hybrid catalyst systems were characterized by several physical methods, such as UV-visible, AAS, SEM and XRD analysis which confirmed the formation of micro- and nano-particle supported catalysts. XRD analysis confirmed metalloporphyrin penetration between montomorillonite layers vertically, horizontally and diagonally, depending on type of the clay crystals. AAS and electronic absorption spectra were used to measure net amounts of metalloporphyrin which penetrated into clay layers. The supported catalyst effectively catalyzed the hydrosilylation reactions of 1-octene with triethoxysilane to produce octyltriethoxysilane. Control experiments confirmed the role of the supported metalloporphyrin in catalyzing the reaction. FTIR was used to monitor the reaction progress with time by observing decay of reactants and production of the product octyltriethoxysilane. The product is industrially valuable as it is commonly used in sensor industry. FTIR, 1HNMR, 13CNMR and Dept 135 techniques confirmed the production of octyltrithoxysilane as a sole reaction product. The catalyst showed very high activity with turnover number values up to 3500 in less than 30 min. Details of catalyst efficiency results are presented together with catalyst characterizations. Effects of different reaction parameters on reaction rates, such as reaction temperature, solvent type, reactant concentration and catalyst recovery, are also discussed