My research is focused on two main objectives, the study of catalytic efficiency and mechanism of palladium nanoparticles stabilized by poly(vinylpyrrolidone) (PVP) for carbon-carbon coupling reactions, and to rationally synthesize metal nanoparticles stabilized by metal-carbon bonds and apply them to catalyze carbon-carbon coupling reactions.<p>
In the first project, Pd nanoparticles stabilized by PVP were used to catalyze carbon-coupling reactions, specifically the Stille and Suzuki reactions. The mechanism of carbon-carbon coupling reactions was studied. The uncertainty of whether nanoparticles or Pd salts are the catalyst was also examined using the same experimental procedure with Pd salts to examine their catalytic activity in carbon-carbon coupling reactions. Results show that the presence of O2 is crucial to the Stille reaction with the Pd nanoparticles, which are nearly completely inert under N2, while the K2PdCl4 precursor is itself quite active for the Stille reaction. However, the Pd nanoparticles were found to be active for the Suzuki reaction with high yields in the absence of O2. The yields for 4-chlorobenzoic acid are higher than 4-bromobenzoic acid and occur for un-catalyzed reactions, for reasons that are still unknown. Finally Au nanoparticles have been tested by the same experimental procedure and have no catalytic activity for these two reactions.<p>
In the second project, the synthesis of Au and Pd monolayer protected clusters (MPCs) with metal carbon covalent linkages was examined, and the stability of the resulting MPCs was tested. UV-Vis spectra and TEM images show the formation of Au and Pd nanoparticles and 1H NMR was used to characterize the ligands attached to the surface of the nanoparticles. The decylphenyl-stabilized Pd MPCs were synthesized successfully and quite stable in air, while decylphenyl-stabilized Au MPCs prepared with the same protocol have less stability and are easily decomposed. XPS spectra indicate the composition of decylphenyl-stabilized Pd MPCs is a combination of Pd0 and Pd2+ species with the Pd2+ species in excess. In addition, alkylphenyl-stabilized Pd nanoparticles were shown to be effective catalysts for carbon-carbon coupling reactions such as Suzuki and Stille reactions as well as hydrogenation reactions. Finally, it was noted that Pd-C bonds could be easily reduced by H2 when performing hydrogenation reactions resulting in nanoparticle aggregation and precipitation under hydrogenation conditions.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-12212010-143820 |
| Date | 16 March 2011 |
| Creators | Bai, Qian |
| Contributors | Scott, Robert W. J., Foley, Stephen, Sanders, David A. R., Soltan, Jafar |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-12212010-143820/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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