Development of tools for mechanistic understanding and optimisation of photochemical reactions

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My project will focus on the development and mechanistic understanding of photocatalytic reactions (in batch or flow)using on-line, compact mass spectrometry (CMS) and flow NMR spectroscopy as analytic tools.At the outset, I will study the alkylation of 1,1-bis(pyridinium) salts as a new type of acyl anion equivalent, using aquaternary ammonium additive as an internal standard. This novel (but non-photocatalytic) synthetic transformationwill serve as a simple platform on which to develop our CMS monitoring capabilities, using a peristaltic pump andsampling valve to circulate a flask-based reaction mixture for on-line analysis. Once this monitoring technique hasbeen optimised, and our 1,1-bis(pyridinium) alkylation method published as a novel transformation, I will begin toinvestigate photocatalytic reactions using CMS monitoring.The novel photocatalytic process that I will target will again be based on 1,1-bis(pyridinium) salts as reagents, but willattempt to generate alpha-pyridium carbon-centred radicals for arene C-H functionalisation in a Minisci-type process.Compact CMS will now be used to optimise reactions conducted in continuous flow, whereby automated protocolswill be used to screen catalysts and conditions.The later part of the PhD project will use CMS and flow NMR to probe the mechanisms of photocatalytic reactionsdeveloped in our lab. In particular, I will attempt to use ion-tagging of a substrate/reactant to obtain quantitativekinetic data, and to study the effect of various intrinsic and extrinsic parameters on the photocatalytic reaction rate(e.g., catalyst, light wavelength/intensity, temperature). Catalyst deactivation processes, and their influence onreaction efficiency, will also be studied (e.g., for 4CzIPN as catalyst). Finally, I will attempt to use a specialisedsampling probe from Mettler-Tolledo to carry out kinetic analysis of heterogeneous photoreactions, such as thegroup's recently developed alpha-C-H thiazoylation of primary a mines in MeCN as the solvent.