Translating Photoredox Reactions into Scalable Electrochemical Processes

将光氧化还原反应转化为可扩展的电化学过程

• 批准号: 2602037
• 金额: --
• 依托单位: University of Bath
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2602037
• 关键词: Translating; Photoredox; Reactions; into; Scalable

Photoredox catalysed reactions have and will continue to expand the scope of chemical transformations. A burgeoning number of novel bond-formation syntheses are published each year, and methodologies will continue to be adopted by industry thanks to commercially available reactors. However, commonly employed photocatalysts include expensive, non-sustainable ruthenium and iridium polypyridyl complexes which tend to deactivate over time and have a fixed and narrow redox window. Electrochemical processes are viable alternatives to photoredox reactions and have seen a renaissance of late; a controllable redox window allows for a myriad of sustainable novel transformations as electrons from a power source can be harnessed. Despite this, organic eletrosynthetic methodologies generally suffer from scalability due to a lack of commercial reactors. We will aim to identify whether certain redox-neutral photoredox reactions can be translated into the electrochemical manifold. We will use paired electrosynthesis, employing either electrodes with a narrow inter-electrode gap, or where there is a global, rapidly alternating current. Within the field of paired electrosynthesis, parallel plate electrodes with small inter-electrode gaps are part of a recent advance, proving that reactions can be run without added electrolytes, however, low flow volume means that reaction scope is limited to microflow operation only. The high cost of fabrication of the reactors is only confounded by its difficulty to clean. Interdigitated band electrode systems offer an attractive alternative, as an inter-electrode gap of less than 5 Ym will allow for interelectrode diffusion of radical intermediates, whilst the high surface area of the interdigitated electrode may lead to flow or batch operations suitable for commercial manufacture.In the first year we aim to discover novel redox-neutral photoredox reactions, current studies focusing on the A-functionalisation of N-allylpyrrolidine. If successful, we will attempt to translate this process, amongst others, such as the known A-C-H functionalisation of unprotected primary amines, to paired electrochemical processes using interdigitated electrodes within batch reactions. This will naturally lead to continuous flow electrosynthesis, where we hope to showcase the C-H functionalisation of gaseous amine feedstocks such as methylamine to enable unprecedented direct access to expensive or difficult to source heterobenzylic amines. We also predict that electrosynthesis will provide a novel synthetic pathway to functionalising molecules that absorb light at a similar wavelength to photocatalysts, developing a new set of reactions that can only be achieved by electrochemistry. Novel synthetic methodology, and simple, scalable protocols for batch and continuous flow electrosynthesis make up some of the potential findings that will be of relevance to our industrial partner, AstraZeneca, and to the wider chemistry community.

光氧化还原催化反应已经并将继续扩大化学转化的范围。每年都有大量新的成键合成方法发表，由于商业上可用的反应器，这些方法将继续被工业采用。然而，常用的光催化剂包括昂贵的、不可持续的钌和铱多吡啶基络合物，其倾向于随时间失活并且具有固定且窄的氧化还原窗口。电化学过程是光氧化还原反应的可行替代方案，并且最近已经看到了复兴;可控的氧化还原窗口允许无数可持续的新颖转化，因为可以利用来自电源的电子。尽管如此，有机电合成方法通常由于缺乏商业反应器而具有可扩展性。我们的目标是确定某些氧化还原中性光氧化还原反应是否可以转化为电化学歧管。我们将使用成对的电合成，采用具有窄电极间间隙的电极，或者存在全局快速交变电流的电极。在成对电合成领域内，具有小电极间间隙的平行板电极是最近进展的一部分，证明反应可以在不添加电解质的情况下进行，然而，低流量意味着反应范围仅限于微流操作。反应器的高制造成本只是由于其难以清洁而混淆。交叉指状带电极系统提供了一个有吸引力的替代方案，因为小于5 μ m的电极间间隙将允许自由基中间体的电极间扩散，而交叉指状电极的高表面积可能导致适合于商业生产的流动或分批操作。在第一年，我们的目标是发现新的氧化还原中性光氧化还原反应，目前的研究集中在N-烯丙基吡咯烷的A-官能化上。如果成功的话，我们将尝试将这个过程，除其他外，如已知的未保护的伯胺的A-C-H官能化，转化为在间歇反应中使用叉指电极的成对电化学过程。这将自然导致连续流电合成，我们希望展示气态胺原料如甲胺的C-H官能化，以实现前所未有的直接获得昂贵或难以获得的杂苄基胺。我们还预测，电合成将提供一种新的合成途径，以功能化吸收光催化剂类似波长的分子，开发一套只能通过电化学实现的新反应。新型的合成方法，以及用于批量和连续流电合成的简单、可扩展的方案构成了一些潜在的发现，这些发现将与我们的工业合作伙伴阿斯利康和更广泛的化学界有关。