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Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
Thermomorphic polyethylene-supported olefin metathesis catalysts
Christopher Hobbs1, Yun-Chin Yang, Johnny Ling
1Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842-3012, USA.
Organic Letters
|June 29, 2011
Summary
Polyethylene-oligomer supported ruthenium catalysts enable efficient, recyclable ring-closing metathesis. These thermomorphic catalysts precipitate upon cooling for easy separation and reuse in homogeneous reactions.
Area of Science:
- Catalysis
- Polymer Science
- Organometallic Chemistry
Background:
- N-heterocyclic carbene (NHC) ligands are crucial in organometallic catalysis.
- Ruthenium (Ru) complexes with NHC ligands are effective catalysts for various transformations, including ring-closing metathesis (RCM).
- Developing recyclable and recoverable catalyst systems is essential for sustainable chemistry.
Purpose of the Study:
- To prepare polyethylene-oligomer (PE(olig))-supported N-heterocyclic carbene (NHC) ligands and their ruthenium (Ru) complexes.
- To evaluate these supported complexes as thermomorphic, recoverable, and recyclable catalysts for ring-closing metathesis (RCM).
- To demonstrate the practical application of these catalysts in homogeneous RCM reactions with facile separation.
Main Methods:
- Synthesis of PE(olig)-supported NHC ligands.
- Complexation of supported ligands with Ru precursors.
- Characterization of the resulting Ru-NHC complexes.
- Application of the catalysts in homogeneous RCM reactions at elevated temperatures.
- Separation of the catalyst by cooling-induced precipitation.
Main Results:
- PE(olig)-supported NHC-Ru complexes were successfully prepared and shown to be structurally analogous to low molecular weight counterparts.
- These supported complexes function as thermomorphic catalysts, enabling homogeneous RCM at 65 °C.
- Upon cooling to 25 °C, the catalysts quantitatively precipitate as solids, allowing for easy separation from reaction products.
- The precipitated catalysts are recoverable and recyclable for subsequent RCM reactions.
Conclusions:
- PE(olig)-supported NHC-Ru complexes offer a viable strategy for developing recyclable homogeneous catalysts.
- The thermomorphic properties facilitate efficient catalyst separation and recovery, enhancing sustainability.
- These systems represent a significant advancement in the field of recoverable metathesis catalysts.
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