Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte
Citation
Source Title
ISSN
Faculty
School
Funding and Sponsorship
Remarks
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry C, copyright © American Chemical Society, after peer review and technical editing by the publisher. To access the final edited and published work seehttps://doi.org/10.1021/acs.jpcc.9b01832.
Collection
Abstract
In this work, we show that the nature of the supporting electrolyte and solvent can dramatically alter the outcome of the electrochemically mediated cleavage of alkoxyamines. A combination of cyclic voltammetry experiments and quantum chemistry is used to study the oxidation behavior of TEMPO-i-Pr under different conditions. In dichloromethane, using a noncoordinating electrolyte (TBAPF6), TEMPO-i-Pr undergoes reversible oxidation, which indicates that the intermediate radical cation is stable toward mesolytic fragmentation. In contrast, in tetrahydrofuran with the same electrolyte, oxidized TEMPO-i-Pr undergoes a rapid and irreversible fragmentation. In nitromethane and acetonitrile, partially irreversible oxidation is observed, indicating that fragmentation is much slower. Likewise, alkoxyamine oxidation in the presence of more strongly coordinating supporting electrolyte anions (BF4-, ClO4-, OTf-, HSO4-, NO3-) is also irreversible. These observations can be explained in terms of solvent- or electrolyte-mediated SN2 pathways and indicate that oxidative alkoxyamine cleavage can be "activated" by introducing coordinating solvents or electrolytes or be "inhibited" through the use of noncoordinating solvents and electrolytes.
Related items
Showing items related by title, author, creator and subject.
-
Silvester-Dean, Debbie ; Jamil, Rabia; Doblinger, Simon; Zhang, Y.; Atkin, R.; Li, H. (2021)Ionic liquids (ILs) have become highly popular solvents over the last two decades in a range of fields, especially in electrochemistry. Their intrinsic properties include high chemical and thermal stability, wide ...
-
Shi, H.; Su, Chao ; Ran, R.; Cao, J.; Shao, Zongping (2020)Solid oxide fuel cells (SOFCs) directly convert chemical energy that is stored in a wide range of fuels into direct current electricity, with high efficiency and low emissions, via a series of electrochemical reactions ...
-
He, S.; Jiang, S.P. (2021)High temperature solid oxide cells (SOCs) consisted of solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) are considered one of the most environmentally friendly and efficient energy conversion ...