Palladium and platinum complexes for the oxidation of small molecules
Abstract/Contents
- Abstract
- Palladium is a versatile metal used prominently in synthesis. The rapid growth of palladium oxidation chemistry in the past decade has spurred a number of new processes that allow for the selective oxidation of substrates under mild conditions. This growth, specifically in the field of aerobic alcohol oxidation, attracted our attention, with the hope that it would provide new catalysts for use in direct methanol fuel cells. Toward that goal we developed a new cationic palladium complex, [(neocuproine)Pd(OAc)]2[OTf]2, which shows unprecedented initial turnover frequencies for aerobic alcohol oxidation at room temperature. However, catalyst lifetimes are limited due to the generation of reactive partially reduced oxygen species that promote oxidation of the ligand and deactivation of the catalyst. The use of milder oxidant like benzoquinone extended catalyst lifetimes prompting a further exploration of the substrate scope. Oxidation of glycerol proceeds exclusively at the secondary alcohol to yield dihydroxyacetone. Other 1,2-diols also favors oxidation of the secondary alcohol. Methanol oxidation proceeds at a much slower rate, but yields methyl formate with selectivities greater than 90 %. The mechanism for this process was probed through the use of model studies and isotopic labels suggesting the transient generation and oxidation of methyl hemiformal. In a parallel effort toward the extension of catalyst lifetimes, a number of new oxidatively resistant ligands were synthesized and used toward the formation of palladium catalysts that exhibit extended catalyst lifetimes. Additional efforts have focused on the use of similar catalyst for the oxidative carbonylation of 1,2- and 1,3-diols to yield 5-membered and 6-membered cyclic carbonates in the presence of N-chlorosuccinimide, iodosylbenzene, or dichloroisocyanuric acid. Finally, a new platinum dimer containing a trimethylplatinum unit and bridging amides was synthesized and characterized. Its reactivity toward the reductive elimination of ethane of methanol derivatives was explored. Additional work with known platinum dimers suggests these species, upon addition of silver triflate, facilitates the C-H activation of a number of unactivated arenes and promotes the C-H functionalization of propargyl aryl ethers.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Copyright date | 2011 |
| Publication date | 2010, c2011; 2010 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Pearson, David Michael |
|---|---|
| Associated with | Stanford University, Department of Chemistry |
| Primary advisor | Waymouth, Robert M |
| Thesis advisor | Waymouth, Robert M |
| Thesis advisor | Kool, Eric T |
| Thesis advisor | Trost, Barry M |
| Advisor | Kool, Eric T |
| Advisor | Trost, Barry M |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | David M. Pearson. |
|---|---|
| Note | Submitted to the Department of Chemistry. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2011. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2011 by David Michael Pearson
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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