Steric hindrance in a MnSalen expoxidation catalyst
- SRI International, Menlo Park, CA (United States)
Many transition metal epoxidation catalysts use porphyrin type ligands, as biomimetic models for the well-studied monooxygenase, Cyt P-450. Recently, non-porphyrin systems based on the Salen ligand have received attention, because high e.e. values are reported using chiral Salen ligands. These systems have yet to be rendered generally practical, however, because the catalyst lifetimes are very short and the turnover numbers low. The original Mn(III) Salen epoxidation catalysts became inactive within 1 h, showing only 5 to 10 turnovers. The modified, chiral Mn(III) Salen complexes show similarly low turnovers. The principal decomposition routes of the MnSalen epoxidation catalysts are not clear. The purpose of the present study is to determine whether incorporation of extreme steric hindrance into the Salen ligand could be used to increase the lifetime of the Mn(III) Salen epoxidation catalysts.
- OSTI ID:
- 250095
- Report Number(s):
- CONF-9508100--
- Country of Publication:
- United States
- Language:
- English
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