Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte
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 u...
| Main Authors: | , , , , |
|---|---|
| Format: | Journal Article |
| Language: | English |
| Published: |
AMER CHEMICAL SOC
2019
|
| Subjects: | |
| Online Access: | http://purl.org/au-research/grants/arc/CE140100012 http://hdl.handle.net/20.500.11937/80752 |
| _version_ | 1848764265663561728 |
|---|---|
| author | Noble, B.B. Norcott, P.L. Hammill, C.L. Ciampi, Simone Coote, M.L. |
| author_facet | Noble, B.B. Norcott, P.L. Hammill, C.L. Ciampi, Simone Coote, M.L. |
| author_sort | Noble, B.B. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | 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. |
| first_indexed | 2025-11-14T11:16:37Z |
| format | Journal Article |
| id | curtin-20.500.11937-80752 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T11:16:37Z |
| publishDate | 2019 |
| publisher | AMER CHEMICAL SOC |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-807522020-08-31T03:47:20Z Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte Noble, B.B. Norcott, P.L. Hammill, C.L. Ciampi, Simone Coote, M.L. Science & Technology Physical Sciences Technology Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Chemistry Science & Technology - Other Topics Materials Science NITROXIDE-MEDIATED POLYMERIZATION CATIONIC-POLYMERIZATION ACETIC-ANHYDRIDE MOLECULAR-WEIGHT SIDE-REACTIONS ACTIVATION 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. 2019 Journal Article http://hdl.handle.net/20.500.11937/80752 10.1021/acs.jpcc.9b01832 English http://purl.org/au-research/grants/arc/CE140100012 http://purl.org/au-research/grants/arc/FL170100041 http://purl.org/au-research/grants/arc/DE160100732 AMER CHEMICAL SOC fulltext |
| spellingShingle | Science & Technology Physical Sciences Technology Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Chemistry Science & Technology - Other Topics Materials Science NITROXIDE-MEDIATED POLYMERIZATION CATIONIC-POLYMERIZATION ACETIC-ANHYDRIDE MOLECULAR-WEIGHT SIDE-REACTIONS ACTIVATION Noble, B.B. Norcott, P.L. Hammill, C.L. Ciampi, Simone Coote, M.L. Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte |
| title | Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte |
| title_full | Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte |
| title_fullStr | Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte |
| title_full_unstemmed | Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte |
| title_short | Mechanism of Oxidative Alkoxyamine Cleavage: The Surprising Role of the Solvent and Supporting Electrolyte |
| title_sort | mechanism of oxidative alkoxyamine cleavage: the surprising role of the solvent and supporting electrolyte |
| topic | Science & Technology Physical Sciences Technology Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Chemistry Science & Technology - Other Topics Materials Science NITROXIDE-MEDIATED POLYMERIZATION CATIONIC-POLYMERIZATION ACETIC-ANHYDRIDE MOLECULAR-WEIGHT SIDE-REACTIONS ACTIVATION |
| url | http://purl.org/au-research/grants/arc/CE140100012 http://purl.org/au-research/grants/arc/CE140100012 http://purl.org/au-research/grants/arc/CE140100012 http://hdl.handle.net/20.500.11937/80752 |