Thavarajah, Rumintha; (2023) A New Approach to the Catalysis of Chemical Reactions using Novel 3D Printed Catalyst Embedded Stirrer Devices. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The work described in this thesis focusses on an exploration of the potential of combining three-dimensional (3D) printing with chemical catalysis in order to aid batch chemical synthesis in round bottom flasks (RBFs), carousel systems, microwave reactors, or large-scale reactions. In this research, stereolithography apparatus (SLA) 3D printed stirrer devices were designed and developed to improve mixing of batch chemical reactions and catalyse them at the same time. Once designed and developed, these were modified to incorporate a range of Lewis acid catalysts into the 3D printed stirrer devices at the point of printing and their effects on chemical reactions were analysed. In the first instance, the reaction of benzene-1,2-diamine with benzaldehyde to synthesise 2,3-disubstituted benzimidazole was investigated. In a comparison screen of the Lewis acid catalysts, we determined that scandium triflate impregnated stirrer devices gave highest yields with lower reaction times under optimised conditions when compared to the use of scandium triflate as a powder alone. In a similar fashion, the reaction of 2-aminobenzothiol and benzaldehydes to synthesise 2-substituted benzothiazoles was examined using yttrium chloride hexahydrate impregnated stirrer devices and similar outcomes to the first reaction was observed. The scope of the catalytic stirrer devices was further explored where dual metal catalysts containing devices were successfully fabricated. Their use in Sonogashira coupling reactions under microwave irradiation gave good yields with reduced reaction times of 75 minutes. It was shown that the use of catalyst impregnated stirrer devices in all reactions excluded the need for weighing out powdered catalysts and made the work up procedure simpler, saving time. The ability to reuse the stirrer devices multiple times was also successfully demonstrated in this thesis. In order to exemplify the benefits of the catalyst impregnated devices, a library of novel derivatives was synthesised in excellent yields. The thesis closes with details of the experimental conditions and the spectral data for all compounds formed.

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