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High-Productivity Single-Pass Electrochemical Birch Reduction of Naphthalenes in a Continuous Flow Electrochemical Taylor Vortex Reactor

Lee, Darren S.; Love, Ashley; Mansouri, Zakaria; Waldron Clarke, Toby H.; Harrowven, David C.; Jefferson-Loveday, Richard; Pickering, Stephen J.; Poliakoff, Martyn; George, Michael W.

High-Productivity Single-Pass Electrochemical Birch Reduction of Naphthalenes in a Continuous Flow Electrochemical Taylor Vortex Reactor Thumbnail


Authors

Darren S. Lee

Zakaria Mansouri

Toby H. Waldron Clarke

David C. Harrowven

Richard Jefferson-Loveday

Stephen J. Pickering



Abstract

We report the development of a single-pass electrochemical Birch reduction carried out in a small footprint electrochemical Taylor vortex reactor with projected productivities of >80 g day-1 (based on 32.2 mmol h-1), using a modified version of our previously reported reactor [Org. Process Res. Dev. 2021, 25, 7, 1619-1627], consisting of a static outer electrode and a rapidly rotating cylindrical inner electrode. In this study, we used an aluminum tube as the sacrificial outer electrode and stainless steel as the rotating inner electrode. We have established the viability of using a sacrificial aluminum anode for the electrochemical reduction of naphthalene, and by varying the current, we can switch between high selectivity (>90%) for either the single ring reduction or double ring reduction with >80 g day-1 projected productivity for either product. The concentration of LiBr in solution changes the fluid dynamics of the reaction mixture investigated by computational fluid dynamics, and this affects equilibration time, monitored using Fourier transform infrared spectroscopy. We show that the concentrations of electrolyte (LiBr) and proton source (dimethylurea) can be reduced while maintaining high reaction efficiency. We also report the reduction of 1-aminonaphthalene, which has been used as a precursor to the API Ropinirole. We find that our methodology produces the corresponding dihydronaphthalene with excellent selectivity and 88% isolated yield in an uninterrupted run of >8 h with a projected productivity of >100 g day-1.

Citation

Lee, D. S., Love, A., Mansouri, Z., Waldron Clarke, T. H., Harrowven, D. C., Jefferson-Loveday, R., …George, M. W. (2022). High-Productivity Single-Pass Electrochemical Birch Reduction of Naphthalenes in a Continuous Flow Electrochemical Taylor Vortex Reactor. Organic Process Research and Development, 26(9), 2674-2684. https://doi.org/10.1021/acs.oprd.2c00108

Journal Article Type Article
Acceptance Date Apr 15, 2022
Online Publication Date Aug 24, 2022
Publication Date Sep 16, 2022
Deposit Date Sep 1, 2022
Publicly Available Date Sep 1, 2022
Journal Organic Process Research and Development
Print ISSN 1083-6160
Electronic ISSN 1520-586X
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 26
Issue 9
Pages 2674-2684
DOI https://doi.org/10.1021/acs.oprd.2c00108
Keywords Organic Chemistry, Physical and Theoretical Chemistry
Public URL https://nottingham-repository.worktribe.com/output/10367800
Publisher URL https://pubs.acs.org/doi/10.1021/acs.oprd.2c00108

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