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。每年都会发布大量新颖的成键合成方法，并且由于商业化的反应器，这些方法将继续被工业界采用。然而，常用的光催化剂包括昂贵的、不可持续的钌和铱聚吡啶络合物，它们往往会随着时间的推移而失活，并且具有固定且狭窄的氧化还原窗口。电化学过程是光氧化还原反应的可行替代方案，并且最近得到了复兴。由于可以利用来自电源的电子，可控的氧化还原窗口可以实现无数可持续的新颖转变。尽管如此，由于缺乏商业反应器，有机电合成方法通常会受到可扩展性的影响。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流形。我们将使用成对电合成，使用电极间间隙较窄的电极，或者存在全局快速交流电的电极。在成对电合成领域，具有小电极间间隙的平行板电极是最新进展的一部分，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。反应器的制造成本很高，而且其难以清洁。叉指带电极系统提供了一种有吸引力的替代方案，因为小于 5 Ym 的电极间间隙将允许自由基中间体在电极间扩散，而叉指电极的高表面积可能导致适合商业制造的流动或批量操作。在第一年，我们的目标是发现新颖的氧化还原-中性光氧化还原反应，目前的研究重点是 A 功能化 N-烯丙基吡咯烷。如果成功，我们将尝试将该过程（例如未受保护的伯胺的已知 A-C-H 官能化）转化为在批量反应中使用叉指电极的配对电化学过程。这自然会导致连续流电合成，我们希望展示甲胺等气态胺原料的 C-H 官能化，从而能够前所未有地直接获得昂贵或难以来源的杂苄胺。我们还预测，电合成将为功能化分子提供一种新的合成途径，这些分子吸收与光催化剂相似波长的光，从而开发出一组只能通过电化学才能实现的新反应。新颖的合成方法以及简单、可扩展的批量和连续流电合成方案构成了一些与我们的工业合作伙伴阿斯利康和更广泛的化学界相关的潜在发现。