Organometallic catalysis for controlled olefin polymerization and oligomerization
Abstract/Contents
- Abstract
- My Ph.D. work primarily involves the synthesis of ethylene-based oligomers and ethylene-styrene copolymers using organometallic catalysis. Chapter 1 reviews selective ethylene oligomerization that produces 1-hexene and 1-octene, with particular emphasis on the chromium-based catalytic systems and the mechanism by which they operate. Its application to the preparation of value-added chemicals is also covered. Chapter 2 and Chapter 3 present investigations on selective ethylene oligomerization with a Cr(PNP)Cl3/MAO catalyst system (PNP = Ph2PN(iPr)PPh2) in the presence of dialkyl zinc as an effective strategy for the co-generation of 1-octene and functionalized ethylene oligomers. Transmetallation with ZnMe2 during Cr-catalyzed ethylene tetramerization generated end-labeled 1-alkenes in Cn> 10 along with 1-octene, while that with ZnEt2 or ZnBu2 produced a mixture of end-labeled linear alkanes and 1-alkenes in Cn> 10 as well as 1-octene. Labeling studies with D2O provided a mechanistic test for metallacycle intermediates. Mechanistic proposals are presented to explain the formation of end-labeled products in the presence of various types of zinc alkyls. Chapter 4 and Chapter 5 examine a series of titanocenes [CpTiCl3, CpTiCl2TEMPO, CpNTiCl3, CpNTiCl2TEMPO, where Cp = C5H5, CpN = C5H4CH2CH2N(CH3)2, and TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl] for styrene homopolymerization and ethylene-styrene (ES) copolymerization at 70 °C and 120 °C to determine the influence of the pendant amine group and the hydroxylaminato ligand on comonomer incorporation and distribution. Titanocenes bearing the pendant amine ligand were active for ES copolymerization, whereas complexes lacking the pendant group afforded only mixtures of homopolymers, revealing the critical role of the pendant amine donor on the copolymerization behavior. At 120 °C, the titanocene complexes with the amine group generated high molecular weight ES copolymers along with an atactic polystyrene (aPS) byproduct. The molecular weight of the ES copolymers produced by a coordination mechanism was found to coincide with that of the aPS produced by a radical polymerization mechanism. A method to separate these two components was developed by the addition of a catalytic chain-transfer agent, cobalt tetraphenylporphyrin, successfully decreasing the molecular weight of the radically-produced aPS and offering expedient separation of the ES copolymer from the aPS. Chapter 6 describes a series of new mono-, bi-, and trimetallic complexes based on the dinucleating ligand, N, N'-bis[2-(diphenylphosphino)phenyl] formamidine (PNNP), which provides two binding sites suitable for accommodating Pd, Ni, Co, Fe, and Cu. Definitive evidence for the structures of all complexes were given by X-ray crystal structures. The synthesis, characterization and crystal structure of each complex are discussed.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2010 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Son, Kyung-Sun | |
|---|---|---|
| Associated with | Stanford University, Department of Chemistry | |
| Primary advisor | Waymouth, Robert M | |
| Thesis advisor | Waymouth, Robert M | |
| Thesis advisor | Du Bois, Justin | |
| Thesis advisor | Frank, C. W | |
| Advisor | Du Bois, Justin | |
| Advisor | Frank, C. W |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Kyung-Sun Son. |
|---|---|
| Note | Submitted to the Department of Chemistry. |
| Thesis | Thesis (Ph. D.)--Stanford University, 2010. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2010 by Kyung-sun Son
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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