| Autor: |
N. Visagie, M.C. Joseph, E.D. Maggott, S.F. Mapolie |
| Jazyk: |
angličtina |
| Rok vydání: |
2024 |
| Předmět: |
|
| Zdroj: |
Results in Chemistry, Vol 12, Iss , Pp 101870- (2024) |
| Druh dokumentu: |
article |
| ISSN: |
2211-7156 |
| DOI: |
10.1016/j.rechem.2024.101870 |
| Popis: |
In this study, a series of neutral ruthenium salicylaldimine complexes were synthesized and evaluated as catalysts for the base-free transfer hydrogenation of carbonyl compounds, including acetophenone. Under base-free conditions, the complexes demonstrated high catalytic activity, achieving conversions of up to 79 % for acetophenone with a turnover number (TON) of 790 after 2 h at 82 °C. Comparatively, when a base (2 mol% KOH) was used, the conversion dropped to 17–25 %. Extending the reaction time to 3 h under base-free conditions increased the conversion to 90 %, with a TON of 900. The catalysts were also tested on a range of substrates: acetophenone derivatives with electron-donating substituents showed conversions up to 89 %, while electron-withdrawing groups resulted in lower conversions (67 %). Additionally, sterically hindered substrates like benzophenone yielded 72 % conversion. Visible light exposure significantly reduced catalytic activity, resulting in up to a 26 % decrease in conversion due to the formation of an inactive bis(salicylaldimine) ruthenium species. Mechanistic studies revealed that the reaction proceeds via an oxidative addition pathway, with the formation of a ruthenium-hydride intermediate confirmed by NMR and FT-IR spectroscopy. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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