Physical Sciences and Mathematics Commons^™

Improved Stoichiometric Synthesis Of Ccc-Nhc Pincer Rh Complexes And Catalytic Activity Towards Dehydrogenative Silylation And Hydrosilylation Of Alkenes, Enock Amoateng

Theses and Dissertations

N-Heterocyclic carbenes (NHCs) have attracted growing interest not only as successful ancillary ligands in a wide variety of transition-metal-catalyzed reactions but have also shown to offer photophysical and electrochemical properties. The metalation/transmetalation strategy using [Zr(NMe₂)₄] as initial metalating reagent offers an efficient approach to the preparation of CCC-NHC pincer complexes of the late transition metals such as Rh and Ir. In the process of investigating an intermediate and the mechanism of the metalation/transmetalation to Rh sequence, a mixed valent bimetallic CCC-NHC pincer Rh complex with two chloro ligands bridged between a [(CCC-NHC)Rh(III)] and a [Rh(I)(COD)] fragment …

The Kinetic Control Of Polymer Micelles; Chemical Functionality, Material Interactions, And Equilibration, Taylor Larison

Theses and Dissertations

Polymer micelles have found significant uses in areas such as, energy storage devices, catalysis, opto-electronics, drug-delivery, oil additives, and nanoreactors. In many of these applications the overall micelle size (aggregation number) and chemical functionalization determines performance. To progress towards more advanced materials synthesized from the facile bottom-up approach with polymeric micelles the implementation and study of thermodynamic handles were investigated. Here the kinetic control of micelles was studied across a range of applications; independent control over micelle functionality, the spatial orientation of multiple metal oxide nanoparticles in mesoporous materials via self-assembly, and the use of small-angle neutron scattering (SANS) to …

Asymmetric Cuh-Catalyzed Reductive Coupling Of Allenamides With Carbonyl Electrophiles & Development Of Nanocatalysts For Heterogeneously Catalyzed Buchwald-Hartwig Amination, Raphael K. Klake

Theses and Dissertations

Many drugs and natural products contain multiple stereogenic carbons bearing heteroatoms throughout their carbon framework. Therefore, methods that can efficiently install multiple heteroatoms on a molecule are valuable. Reductive coupling reactions have been extensively studied, and the allylation of carbonyls via the reductive coupling approach has been a key method for generating chiral tertiary and secondary allylic alcohols. This work utilizes inexpensive Cu for the asymmetric reductive coupling of allenamides with carbonyls to simultaneously install two heteroatoms (oxygen and nitrogen) on the product. These molecules have a polarity profile that make them difficult to make using traditional methods. Herein, we …

Aqueous Kinetics Of Α-Hydroxyhippuric Acid Derivatives Bearing Electron-Withdrawing Groups As A Function Of Ph And Buffer Catalysts, Mohamad Imad Rafie

Theses and Dissertations

It has been shown that carbinolamides are intermediates in the enzyme-catalyzed synthesis of -amidated peptides. Although carbinolamides are important intermediates in the production of these hormones and have roles in other biological venues, little attention has been given to their mechanisms of reaction in water, and, thus, it is difficult to speculate how their reaction would be enzymatically catalyzed. The purpose of the work presented here was to synthesize structural analogs of the biological intermediates and study their mechanism of breakdown in water. -Hydroxyhippuric acid, a substrate for the enzymatic system, provides an easily modified template for the study of …

The Investigation Of Nickel-Based Catalysts For The Oxidative Dehydrogenation Of Ethane, Justin Lane Park

Theses and Dissertations

The Investigation of Nickel-Based Catalysts for the Oxidative Dehydrogenation of Ethane Justin Lane ParkDepartment of Chemistry & Biochemistry, BYU Doctor of Philosophy Chemistry The advancement of creating ethylene from ethane via oxidative dehydrogenation (ODH) rather than the traditional direct dehydrogenation is right on the cusp of commercialization. The oxidative pathway provides a novel route that reduces the operating temperature of this reaction by 400-500°C. A variety of metals including Mo, V, and Ni that have redox properties suitable for the partial oxidation of small chain alkanes have been investigated. Currently, a MoVNbTe oxide is the most promising catalyst but it …

Biosensing And Catalysis Applications Of Nanoporous Gold (Npg) And Platinum-Speckled Nanoporous Gold (Npg-Pt) Electrodes, Christopher J. Freeman

Theses and Dissertations

The importance of porous materials has risen substantially in the last few decades due to their ability to reduce the size and cost of bioanalytical devices and fuel cells. First, this work aims to describe the fabrication of nanoporous gold (NPG) electrodes that are resistant to electrode passivation due to fibrinogen biofouling in redox solutions. The effect on potentiometric and voltammetric experiments was seen as a deviation from ideal behavior on planar gold electrodes, whereas NPG electrodes were consistently behaving in a Nernstian fashion at low concentrations of ferri-ferrocyanide (£100 mM). An improvement in electrode behavior on NPG electrodes versus …

The Investigation Of Oxidative Addition Reactions Of Metal Complexes In Cross-Coupling Catalytic Cycles Based On A Unique Methodology Of Coupled Ion/Ion-Ion/Molecule Reactions, Mariah L. Parker

Theses and Dissertations

Popular catalytic cycles, such as the Heck, Suzuki, and Negishi, utilize metal centers that oscillate between two oxidation states (II/0) during the three main steps of catalysis: reductive elimination, oxidative addition, and transmetallation. There has been a push to use less toxic, cheaper metal centers in catalytic cycles, leading to interest in first-row transition metals, such as nickel and cobalt. With these metals, the cycles can potentially pass through the +1 oxidation state, which acts as reactive intermediates, undergoing oxidative additions to form products, potentially with radical characteristics. The oxidative addition steps of catalytic cycles are critical to determining overall …

Laser Synthesis Of Nanomaterials Incorporated Within High Surface Area Materials: Applications For Heterogeneous Catalysis, Water Treatment, And Photothermal Energy Conversion, Julian A. Bobb

Theses and Dissertations

Chemical methods are generally used for the synthesis of active nanoparticles (metals, semi-metals, metal oxides, and etc) supported on high surface area materials. Chemical methods involve using strong solvents, harmful gases (H₂ & CO), and high temperature techniques such as high boiling solvents, calcination and pyrolysis. The main drawbacks of using this approach, is the prevalence of chemical agents on nanomaterials which tends to negate its applications. Alternatively, photochemical and photothermal methods are widely being considered for the synthesis and design of nanomaterials.

For these studies, the active nanomaterials incorporated within high surface area materials were prepared by the …

Hydrodesulfurization Of Dibenzothiophene Using Lanthanum Doped Comos2, Carolina Valdes Bracamontes

Theses and Dissertations

Hydrodesulfurization (HDS) is a technique used in petrochemical industry for the removal of sulfur from crude oil. Using dibenzothiophene (DBT) as a target molecule and CoMoS2 catalysts doped with various concentrations of lanthanum were studied for catalytic activity in the removal of DBT from solution. Catalysts were synthesized using ammonium tetrathiomolydate, cobalt chloride and lanthanum nitrate under a solvothermal decomposition in decalin at 350 °C with H2 gas at 160 psi. To evaluate decomposition effects, a second set of catalyst precursors were decomposed in a tube furnace at 450 °C under a constant flow of 10%/90% H2/Ar. Characterizations of the …

Investigation Of Catalytic Oxidation And Coupling Reactions On Gold, Palladium, And Gold-Palladium Alloys, Theodore Douglas Thuening

Theses and Dissertations

Polyvinyl acetate is a common adhesive and additive to emulsion-based paints produced in the millions of tons per year through the palladium catalyzed coupling of ethylene and acetic acid. Understanding the reaction mechanism and kinetics is integral to designing a more efficient catalyst through an increase in activity, selectivity, or both. It has been shown that selectivity for the vinyl acetate monomer (VAM) reaction increases to ~94% upon alloying palladium with gold compared to palladium alone (~80% selective).

The characterization of the VAM formation reaction on Pd(111) and Au/Pd(111) single crystal alloys has been extensively studied, but it has been …

Electrophilic Catalysis Using Heterobimetallic Complexes, Whitney Kaye Walker

Theses and Dissertations

Conventional ligand design in transition metal catalysis capitalizes on the ability of phosphorous, nitrogen, carbon, oxygen, and sulfur-based donors to modify the steric and electronic properties of a reactive metal center. Heterobimetallic transition metal complexes that contain a dative metal-metal bond provide a unique approach to ligand design where the reactivity of the metal center can be modified by metal-metal electronic communication. Our laboratory is interested in using the unique properties of heterobimetallic complexes to address significant limitations in current transition metal catalysis. My PhD work has focused on the ability of early/late transition metal heterobimetallic complexes to facilitate catalysis …

Shaping Metallic Nanoparticles Toward Integrated Plasmonics And Catalysis, Qingfeng Zhang

Theses and Dissertations

Noble metal nanoparticles have been of tremendous interest because of their intriguing size- and shape-dependent plasmonic and catalytic properties. The combination of tunable plasmon resonances with superior catalytic activities on the same nanoparticle, however, has long been challenging because plasmonics and catalysis require nanoparticles in two drastically different size regimes. Tunable plasmon resonances is a unique feature of sub-wavelength metallic nanoparticles, whereas heterogeneous catalysis requires the use of sub-5 nm nanoparticles as the catalysts. In this dissertation, I firstly found a unique way to bridge this size gap between nanoplasmonics and nanocatalysis. I demonstrated that desired plasmonic and catalytic properties …

Sol-Gel Assembly Of Metal Nanostructures Into Metallic Gel Frameworks And Their Applications, Xiaonan Gao

Theses and Dissertations

The advent of nanoscience and nanotechnology has sparked many research forefronts in the creation of materials with control over size, shape, composition, and surface properties.^1,2 However, for most of the applications, nanoscale materials need to be assembled into functional nanostructures that exhibit useful and controllable physical properties. Therefore, numerous efforts on the assembly of nanoparticles (NPs) using organic ligands, polymers and polyelectrolytes have been reported.^3,4 However, the interactions between NPs are mediated by intervening ligands, which are detrimental to charge transport and limit the thermal stability. Hence, developing a new method to produce solid …

A Study Of Allylic Aminations As Catalyzed By Heterobimetallic Pd-Ti Complexes, Diana Lauren Ellis

Theses and Dissertations

Heterobimetallic complexes present a unique approach to catalyzing challenging reactions. By having two metals in close proximity to each other, the metals are able to interact and alter their electronics in a way that simple organic ligands (carbon, nitrogen, sulfur etc.) cannot. Our studies of heterobimetallic complexes focus on a Pd–Ti complex. The complex features a dative interaction between the palladium and the titanium held together by a phosphonamide scaffold. This interaction increases the electrophilicity of the palladium and makes it a very suitable catalyst for allylic amination reactions. We have conducted extensive studies of this catalyst in allylic aminations, …

Catalytic Activity Of Heteropoly Tungstophosphoric Acid Supported On Partially Reduced Graphene Oxide Prepared By Laser And Microwave Irradiation, Mark Paul Jimena Dailo

Theses and Dissertations

The solid acid catalyst of the Keggin-type 12-tungstophosphoric acid (H₃PW₁₂O₄₀, HPW) is supported on partially reduced graphene oxide (PRGO) nanosheets for acid-catalyzed reactions. HPW is a new class of catalyst with a good thermal stability and high Bronsted acidity in order to replace common mineral acids. However, it has low specific surface area (1-5 m²/g). Therefore, the possibility of PRGO as a catalytic support for HPW is investigated due to its high surface area (2630 m²/g) and good thermal stability. The synthesis of HPW-GO catalyst is prepared using microwave and …

I. Studies On The Organocatalytic Formation Of Quaternary Stereocenters. Ii. Studies On The Claisen Rearrangement As A Route To Quaternary Stereocenters. Iii. Asymmetric Synthesis Of Aldehydes Bearing Quaternary Carbon Centers Via The Decarboxylative Asymmetric Allylic Alkylation, Eduardo Alberch

Theses and Dissertations

The asymmetric synthesis of all carbon quaternary stereocenters poses a particular challenge due to the steric congestion inherent in the formation of such centers and has been the object of intense research these last 20-30 years. However, the amount of literature for the synthesis of aldehydes bearing quaternary stereocenters via enolate type chemistry is much more limited due to problems associated with the alkylation of such substrates including such types as Cannizzaro and Tischenko related reactions or self aldol condensations. The formation of aldehydes with quaternary stereocenters via use of enolate equivalents such as the DAAA (decarboxylative asymmetric allylic alkylation) …

New Bimetallic Iridium Cluster Carbonyl Complexes, Mingwei Chen

Theses and Dissertations

Platinum group metal derived bimetallic clusters have been used as precursors to nanoscale catalysts which have been proven to be more effective than their monometallic counterparts. Iridium is a platinum group metal and its applications in catalysis continue to grow. To take advantages of synergies between mixed-metals, we modified iridium clusters with other metal ligands like tin, germanium, and group IB (gold, silver, copper) etc. and obtained a fairly large amount of new iridium derived bimetallic clusters which could be precursors to catalysts with superior properties than that available nowadays. The reaction of Ir4(CO)12 with Ph3SnOH in the presence of …

Rhenium Trioxide, Rhenium Heptoxide And Rehnium Trichloride As Hydrogenation Catalysts, William J. Bartley

Theses and Dissertations

The purpose of this study was to characterize the catalytic activity of rhenium trioxide and rhenium trichloride as hydrogenation catalysts. Work was also undertaken to further study the catalytic properties of rhenium heptoxide. The activity of this latter compound had received some study in a previous project. A complete review of the literature has been made on the organic and inorganic chemistry of rhenium trioxide and rhenium trichloride. A survey of the literature on catalytic hydrogenation and the chemistry of rhenium heptoxide has also been included. Rhenium trioxide was prepared by three similar methods. The first two involved the formation …

Rhenium Catalysis I. Hydrogenation And Hydroformylation Using Rhenium Carbonyl Compounds ; Ii. Hydrogenation Using Catalysts Obtained From The Reduction Of Perrhenates With Metals In Aqueous Solution, Terry G. Selin

Theses and Dissertations

The purpose of this work was to investigate the catalytic activity in both hydrogenation and hydroformylation reactions of rhenium preparations which have not been previously characterized. Rhenium pentacarbonyl was prepared in good yield from rhenium heptoxide and carbon monoxide. The optimum conditions for preparation were 25 hours per gram of dry rhenium heptoxide at 250° under 3000 psig. (initial) of carbon monoxide. Rhenium chloropentacarbonyl was prepared in 62% yield from potassium chlororhenite and carbon monoxide at high temperatures and pressures. The iodopentacarbonyl was prepared in 29% yield from potassium perrhenate, methyl iodide, and carbon monoxide. The preparation of rhenium hydrocarbonyl …

Iron And Cobalt Salts As Catalysts In The Oxidation Of Sodium Sulfite By Free Oxygen, Loren C. Bryner

Theses and Dissertations

The present investigation was carried out to show the catalytic effect of some iron and cobalt salts on the oxidation of sodium sulfite solutions by free oxygen. The rate of reaction was determined by measuring the volume of water required to replace the absorbed oxygen. A photograph and diagrammatical arrangement of the apparatus is given, (Page 14). From the preliminary experiments it was found that the rate of oxidation of sodium sulfite solutions is dependent upon concentration, and speed of the shaker.