Development of tools for mechanistic understanding and optimisation of photochemical reactions

本课题将重点研究光催化反应(间歇或流动光催化反应)的发展和机理，以在线、紧凑质谱学(CMS)和流动核磁共振波谱为分析工具。首先，我将以季铵盐添加剂为内标，研究1，1-二(吡啶)盐的烷基化反应作为一种新型的酰基阴离子当量。这种新颖的(但非光催化的)合成转化将作为一个简单的平台，在其上发展我们的CMS监测能力，使用蠕动泵和取样阀使基于烧瓶的反应混合物循环，用于在线分析。一旦这一监测技术被优化，我们的1，1-双(吡啶)烷基化方法作为一种新的转化方法被发表，我将开始使用CMS监测来研究光催化反应。我将瞄准的新的光催化过程将再次基于1，1-双(吡啶)盐作为试剂，但将尝试在微型过程中生成用于芳烃C-H官能化的α-吡啶碳中心自由基。紧凑型CMS现在将被用于优化在连续流程中进行的反应，由此将使用自动化协议来筛选催化剂和条件。PHD项目的后期部分将使用CMS和Flow核磁共振来探索我们实验室开发的光催化反应的机理。特别是，我将尝试使用底物/反应物的离子标记来获得定量的动力学数据，并研究各种本征和外在参数(例如，催化剂、光波长/强度、温度)对光催化反应速率的影响。还将研究催化剂的失活过程及其对反应效率的影响(例如，以4捷克IPN为催化剂)。最后，我将尝试使用Mettler-Tolledo的特殊采样探针来进行多相光反应的动力学分析，例如该小组最近开发的以MeCN为溶剂的伯胺的α-C-H硫氮化反应。

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.