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Highly regioirregular polypropylene from asymmetric group 4 anilide(pyridine)phenoxide complexes.
Rachel C Klet1, David G VanderVelde, Jay A Labinger
1Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, California 91125, USA.
Chemical Communications (Cambridge, England)
|May 29, 2012
Summary
Group 4 metal complexes with an anilide(pyridine)phenoxide ligand, activated by methylaluminoxane (MAO), effectively catalyze the production of highly regioirregular polypropylene.
Area of Science:
- Organometallic Chemistry
- Polymer Science
Background:
- Group 4 metal complexes are crucial catalysts in olefin polymerization.
- Ligand design significantly influences catalyst activity and polymer properties.
- Methylaluminoxane (MAO) is a common activator for Ziegler-Natta and metallocene catalysts.
Purpose of the Study:
- To investigate the catalytic performance of novel Group 4 complexes featuring an anilide(pyridine)phenoxide ligand.
- To explore the impact of these complexes, activated by MAO, on polypropylene microstructure.
- To understand the structure-activity relationships governing the formation of regioirregular polypropylene.
Main Methods:
- Synthesis and characterization of Group 4 metal complexes with an anilide(pyridine)phenoxide ligand.
- Polymerization of propylene using these complexes activated with MAO.
- Analysis of the resulting polypropylene using techniques such as Nuclear Magnetic Resonance (NMR) spectroscopy to determine regioirregularity.
Main Results:
- The Group 4 complexes effectively catalyzed propylene polymerization.
- The resulting polypropylene exhibited a high degree of regioirregularity.
- The anilide(pyridine)phenoxide ligand structure was found to be key to achieving this regioirregularity.
Conclusions:
- Group 4 complexes bearing an anilide(pyridine)phenoxide ligand are active catalysts for propylene polymerization.
- These catalytic systems produce highly regioirregular polypropylene, indicating a disruption of stereocontrol.
- The ligand architecture plays a critical role in controlling the stereochemistry of the polymerization process.
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