Chemistry Commons^™

The Alpha-Activator Complex, Cellular Maturation, And Catalytic Mechanism Of Iron-Type Nitrile Hydratase, Wasantha Lankathilaka Karunagala Pathiranage

Dissertations (1934 -)

In industry, chemicals are typically synthesized through catalytically accelerated chemical processes. The use of biocatalysts is an increasingly important trend in achieving environmentally friendly chemical production processes. Nitrile Hydratases (NHases) are well-known biocatalysts that are used by several manufacturers such as Mitsubishi Rayon Corporation and Lonza for the conversion of acrylonitrile to acrylamide and 3-cyanopyridine to nicotinamide, respectively. Amides, in general, are used in polymer preparation, adhesive manufacturing, and the paper industry. Refrigeration is needed in the enzymatic hydration process on the industrial scale to maintain a low reaction temperature to stabilize the NHase enzyme. The use of whole cells …

Photoelectrochemical Catalysis Of Hydrogen Peroxide With Tellurium Containing Chromophores, James Eliott Lohman

Dissertations and Theses

Growing concerns over climate change and demand for energy worldwide have made development and implementation of alternative energy sources more necessary than ever. Many of the leading energy alternatives suffer from inconsistent energy production due to fluctuations in availability of natural resources, and the current methods of addressing the issue have tremendous ecological and social ramifications of their own. While fuels like hydrogen gas are providing some promise of relief, the scope of infrastructure changes necessary for implementation and the implicit hazards of the use of such fuels complicate their application as an immediate solution. However, hydrogen peroxide carries far …

Interfacial Amino Acids Support Spa47 Oligomerization And Shigella Type Three Secretion System Activation, Hannah J. Demler, Heather B. Case, Yalemi Morales, Abram R. Bernard, Sean J. Johnson, Nicholas E. Dickenson

Chemistry and Biochemistry Faculty Publications

Like many Gram-negative pathogens, Shigella rely on a type three secretion system (T3SS) for injection of effector proteins directly into eukaryotic host cells to initiate and sustain infection. Protein secretion through the needle-like type three secretion apparatus (T3SA) requires ATP hydrolysis by the T3SS ATPase Spa47, making it a likely target for in vivo regulation of T3SS activity and an attractive target for small molecule therapeutics against shigellosis. Here, we developed a model of an activated Spa47 homo-hexamer, identifying two distinct regions at each protomer interface that we hypothesized to provide intermolecular interactions supportingSpa47 oligomerization and enzymatic activation. Mutational analysis …

Synthesis And Characterization Of A Homogeneous Cobalt Catalyst For The Hydrogenation Of Acetone To Isopropanol, Joselyn G. Molina

Honors Projects

To lessen environmentalstrain and decrease dependency on noble metals for catalysis, first-row metals are continuously being explored as alternative catalysts for reactions of interest, particularly those that close the carbon cycle or promote fuel production. Recently, homogeneous cobalt catalysts have been shown to be viable options for effective hydrogenation of C-O double bonds, with cobalt-triphos being of particular interest. Here, we report the characterization of synthesized a cobalt-triphos complex by nuclear magnetic resonance spectroscopy and optical spectroscopy. Analysis of the electrochemistry of the cobalt-triphos complex suggests promising electrocatalytic capability for the hydrogenation of acetone to produce isopropanol.

Oxidative C–C And C–Heteroatom Reactivity Of High-Valent Nickel Complexes, Sofia Marie Smith

Arts & Sciences Graduate Student Theses and Dissertations

ABSTRACT OF THE DISSERTATIONOxidative C–C and C–Heteroatom Reactivity of High-Valent Nickel ComplexesbySofia M. SmithDoctor of Philosophy in ChemistryWashington University in St. Louis, 2019Professor Liviu M. Mirica, ChairProfessor Kevin D. Moeller, Co-ChairNickel catalysts are commonly used for cross-coupling reactions such as Negishi, Kumada and Suzuki couplings. While Ni(0), Ni(I), and Ni(II) intermediates are most relevant in these transformations, Ni(III) and Ni(IV) species have also been recently proposed to play a role in catalysis. The formation of C–C and C–heteroatom bonds plays a fundamental role in organic transformations, and today cross-coupling reactions are one of the most powerful tools for the construction …

Nontraditional Hydrogen Bonding In Asymmetric Lewis Acid Catalysis, Brandon Vernier

Electronic Theses and Dissertations

In the field of asymmetric induction, there is a shift from the synthesis of reaction

specific chiral auxiliaries towards a broader mechanistic approach. Our approach is to

develop a theory of asymmetric catalyst design from first principles. The Diels-Alder

reaction of 2-methacrolein and 1,3-cyclopentadiene in the presence of 15 mole % lmenthoxy

aluminum dichloride, reported by Koga, achieved the (S)-exo-Diels-Alder

cycloadduct with 72% ee (0% ee Endo for acrolein). The dramatic change from 72% to 0%

ee is a significant fact that has been overlooked in practical organic synthesis.

In the first phase of this work, the conformational landscape of …

Preparation Of Enantioenriched Alkyltin Species And Their Application In Stereospecific Transformations, Glenn O. Ralph

Dissertations, Theses, and Capstone Projects

Organometallic reagents containing the tin-carbon bond are used extensively in modern synthetic chemistry for the formation of new bonds to carbon. Over recent decades, transition metal catalyzed cross coupling reactions between two C(sp²) centers have been widely developed. However, the introduction of a C(sp³) center complicates the catalytic cycle, and opens unproductive chemical pathways which lead to isomerization, elimination, and racemization. Our lab has developed a modified-Stille reaction to combat the deleterious effects of β-hydride elimination. Our protocol enables unactivated 2° alkyl organotin nucleophiles to undergo efficient cross coupling reactions with C(sp²) electrophiles, avoiding …

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 …

Engineering High Reaction Economy Or, An Intensification/Scoring Program For The Preparation Of Simple And Complex Molecules, Caleb J. Kong

Theses and Dissertations

Success of newly discovered chemistry in academia is often scored in terms of its novelty and level of scholarship. In industrial settings, cost, safety and quality are often times the ruler by which new processes are measured. Our group has identified that there is a gap between these two measures of success and has sought to develop principles in order formalize an approach to synthetic strategy and developing ready-to-implement manufacturing processes for molecules, simple and complex.

Some of these principles include (1) the development and application of new chemical methods and reactor technologies (2) recognition of globally amenable chemical environments …

Nucleophilic Phosphine Addition: Exploration Of Novel Alkyne Transformations, Brett Pierce

Murray State Theses and Dissertations

Nucleophilic phosphine catalysis has demonstrated its value in synthetic chemistry by allowing for mild carbon-carbon bond formation. Many phosphine-catalyzed reactions with electron-deficient alkynes have been reported in recent years, leading to an array of valuable products. Stemming from this field of study, phosphines can also be utilized as mild chemoselective reductants for alkynes, resulting in the corresponding alkenes. Herein, a mild, stereoselective, phosphine-mediated partial reduction of alkynes to (E)- and (Z)-alkenes is described. Specifically, a general method for the partial reduction of ynoates to the corresponding (E)- and (Z)-enoate, …

Mechanochemically Synthesized Cobalt Oxide-Based Particles For The Reduction Of Nitrophenols And Impacting Factors To Its Mechanism, Lorianne R. Shultz

Honors Undergraduate Theses

Mechanochemically synthesized cobalt oxide-based particles are employed for the catalytic reduction of 4-nitrophenol (4NP), a toxic water contaminant. This reduction produces 4‑aminophenol (4AP), a less toxic, pharmaceutical precursor for drugs such as paracetamol. The indicated reduction has been completed previously using noble metals and/or catalysts requiring extensive solvent use, and time as part of their preparation. The cost and synthesis of these noble metal catalysts hinders the sustainable broad scale application as an environmental remediation solution. The catalyst synthesis explored in this study utilizes the green chemistry technique of vibratory ball-milling and annealing cobalt oxide-based particles at different temperatures, producing …

Amino-Functionalized Mesostructured Cellular Foam Silica: A Highly Efficient And Recyclable Catalyst In The Knoevenagel Condensation Reaction, Dong Hao, Hongyuan Yang, Tengfei Zhang, Qing Liu

Turkish Journal of Chemistry

Mesostructured cellular foam silica was functionalized by an amino group (MCF-NH$_{2})$ using the postsynthesis grafting method and utilized as a recyclable catalyst for the Knoevenagel reaction to afford $\alpha $, $\beta $-unsaturated compounds. The catalyst was systematically characterized by various analyses such as nitrogen adsorption, X-ray diffraction, Fourier transform infrared spectrophotometry, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and Hammett indicator method. The results showed that MCF-NH$_{2}$ catalyst was successfully prepared with a high surface area of 215 m$^{2}$ g$^{-1}$ and a large pore volume of 1.37 cm$^{3}$ g$^{-1}$. Compared with the nonfunctionalized MCF sample, the window and cell …

Peripherally 1,2-Dinaphthyl Ethanediol Substituted Phthalocyanine Complexes: Synthesis, Characterization, Aggregation, And Application In Benzyl Alcohol Oxidation At Room Temperature, Hali̇l Zeki̇ Gök, Mustafa Kemal Yilmaz

Turkish Journal of Chemistry

In this study, the synthesis of a novel 1,2-dinaphthyl ethanediol substituted phthalonitrile (2) together with tetra-substituted zinc(II) phthalocyanine (Pc) (3) and cobalt(II) Pc (4) bearing 1,2-dinaphthyl ethanediol at peripheral positions was described. The aggregation behaviors of metallophthalocyanines 3and 4 in solution were investigated by carrying out Beer-Lambert experiments at different concentrations. In addition, the catalytic activity of new cobalt(II) Pc 4 was investigated for benzyl alcohol oxidation. Benzyl alcohol was converted to benzaldehyde using cobalt(II) Pc 4 as a catalyst by a conversion of 99% with selectivity of 100% at room temperature in 1 h. Several spectroscopic techniques such as …

New Synthetic Methods Using Superelectrophiles, Sean Kennedy

Graduate Research Theses & Dissertations

The work outlined in this dissertation describes new synthetic methods in the synthesis of heterocyclic compounds mediated by superacid catalysis. Superacids are powerful reagents that enhance the reactivity of electrophiles, thereby opening the door to new reactive pathways with very weak nucleophiles. In this work, trifluoromethanesulfonic acid (triflic acid, CF3SO3H) is employed as a superacid catalyst to effect new transformations. These concepts are summarized in chapter 1. Chapter 2 describes a new acid-catalyzed cascade leading to the indolizidine ring system, which is present in a number of natural products. Experiments support a proposed mechanism involving vinylogous keto-enol tautomerization. The synthesis …

Synthesis, Characterization, And Catalytic Activity Of Copper Palladium Oxide Solid Solutions., Gregory L. Christensen

Department of Chemistry: Dissertations, Theses, and Student Research

Cu_xPd_1-xO forms a homogeneous solid solution over the wide range of 0 ≤ x ≤ 0.725 in which compositional variation can be correlated with structural and chemical environmental changes. After a small lag at low Cu²⁺ concentrations, where the lattice cell parameters are pinned to that of the pure PdO structure, Cu_xPd_1-xO lattice parameters follow Vegard’s law in which the cell volume decreases linearly with x, indicating a homogenous solution in which Cu²⁺ randomly replaces the larger Pd²⁺ cation. The crystal structure also undergoes an increase in the c/a …

Development Of Copper-Catalyzed Suzuki-Miyaura Coupling Using Alkylboron Reagents And Nickel-Catalyzed Alkene Dicarbofunctionalization Reactions, Prakash Basnet

Chemistry and Chemical Biology ETDs

This thesis is divided into two parts. The first part deals with the development of copper-catalyzed Suzuki-Miyaura coupling of alkylboron reagents for the first time. In the second part, we will discuss the development of novel nickel-catalyzed alkene dicarbofunctionalization reactions.

Part I. Cross-coupling reactions are versatile tools to form new carbon-carbon bonds and are widely used in the synthesis of various drug molecules, natural products and materials. However, these reactions are typically catalyzed by palladium, an expensive and rare metal which makes the reaction unsustainable in long-terms. Additionally, palladium-catalyzed cross-coupling reactions with alkylorganometallic reagents suffer from side reactions due to …

Synthesis And Characterization Of Transition Metal Based Nanocomposites For Orr In Fuel Cell Applications, Hunter Austin Wayland

Theses and Dissertations

Development of economically viable platinum alternatives for polymer electrolyte membrane fuel cells is a fundamental step towards large-scale commercialization efforts, which aim to reduce reliance on non-renewable energy resources. This work explores the synthesis, characterization, and application of graphene supported cobalt(III) and iron(III) based MN4 complexes for oxygen reduction, and farther investigates the potential for gains in performance and enhanced stability following coating with a bioinspired self- assembling polymer, polydopamine. The nanocomposites were characterized using a variety of electron microscopy and spectroscopy techniques, and their electrochemical performance was assessed using a potentiostat/galvanostat. The polymer-uncoated nanocomposites were found to reduce oxygen …

Examining The Effects Of Amino And Thiolate Ligands On The Reactivity And Selectivity Of Palladium On Carbon In Hydrogenation Reactions, Eric Liu, Christina Li

The Summer Undergraduate Research Fellowship (SURF) Symposium

Heterogeneous catalysts are used widely by chemical and energy industries because they show high reactivity but often suffer from lack of selectivity. On the other hand, ligands are commonly used in homogeneous catalysts to control the reactivity and selectivity; however, the effects of the ligands on the steric and electronic properties of heterogeneous catalysts are less understood. We examine the effects of four different ligands: 1-adamantanethiol, 1-adamantylamine, 1-dodecanethiol, and 1-dodecylamine, for the commercial hydrogenation catalyst palladium on carbon. Hydrogenation reactions are used as a screening tool to see the behavior that the different catalysts exhibit in the presence of unsaturated …

Electronic Effect Of Platinum Alloy Catalysts On Olefin Hydrogenation Kinetics, Colin Reedy, Jeff Miller, Stephen Purdy

The Summer Undergraduate Research Fellowship (SURF) Symposium

Dehydrogenation of alkanes is the first step in transforming light hydrocarbons into liquid fuels and chemicals. This process has traditionally used platinum alloys as catalysts. Alloys are used industrially because they have a greater selectivity than monometallic platinum. Alloying platinum with an inactive promoter modifies the crystalline structure of the surface (geometric effect), and the 5d electrons in platinum responsible for chemistry (electronic effect); both have been suggested to be primarily responsible for dehydrogenation selectivity in platinum alloys. Alloy catalysts have been synthesized using early 3d transition metal promoters with the same Pt₃M crystal structure. X-Ray Absorption Spectroscopy …

Assessment Of Catalytic Function Of Gold Nanorod-Bound Tempo Under Nir Irradiation, Kristi L. St. Clair

Honors College Theses

Gold nanoparticles are of interest to a number of fields due to their size-dependent optical properties, high stability, and large surface area. The combination of these properties allows for a variety of uses including photothermal therapy, drug delivery and catalysis. Gold nanorods (GNR) absorb light of a given wavelength which stimulates the oscillation of electrons on the surface and is known as the surface plasmon resonance effect. The localized heating of rods via irradiation may cause enhanced effectiveness of an attached organic catalyst which allows the oxidation of alcohols to occur at room temperature. Previously, similar catalytic systems required high …

Combined Theoretical And Experimental Investigation Of Hydrogen Production Catalysis, Carolyn Noelle Virca

Dissertations and Theses

The widespread use of solar energy has been limited in part by the issue of effective storage. Water splitting is a means of converting solar energy into chemical fuel, in the form of hydrogen gas. It can be performed through both photochemical and electrochemical processes, via the two half reactions of water oxidation and proton reduction. Electrochemically, the catalyst receives electrons from an external circuit, which can be coupled to a renewable source such as a solar cell. Photochemically, a light-absorbing molecule provides an excited electron to a catalyst, which either generates oxygen or hydrogen gas. The work described herein …

Imidazolium Ionic Liquids As Multifunctional Solvents, Ligands, And Reducing Agents For Noble Metal Deposition Onto Well-Defined Heterostructures And The Effect Of Synthetic History On Catalytic Performance, Michael Drake Ballentine

Masters Theses & Specialist Projects

1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]Tf2N) was investigated as a multifunctional solvent, ligand, and reducing agent for platinum deposition onto well-defined CdSe@CdS nanorods. Platinum deposition was carried out thermally and photochemically using Pt(acac)2 as the metal precursor. Thermal deposition was investigated in [BMIM]Tf2N with and without addition of a sacrificial reducing agent, and product topology was compared with the products obtained from polyol reduction using 1,2-hexadecanediol, oleic acid, and oleylamine in diphenyl ether. Photochemically induced platinum deposition was carried out at room temperature in [BMIM]Tf2N, and product topology was compared with the photodeposition products obtained from a toluene dispersion. Thermal deposition of platinum …

Synthesis And Catalytic Activity Of (3,4-Diphenylcyclopentadienone)Iron Tricarbonyl Compounds In Transfer Hydrogenations And Dehydrogenations, Timothy W. Funk, Andrew R. Mahoney, Rebecca A. Sponenburg, Kathryn P. Zimmerman, Daniel K. Kim, Emily E. Harrison

Chemistry Faculty Publications

Four (3,4-diphenylcyclopentadienone)iron tricarbonyl compounds were synthesized, and their activities in transfer hydrogenations of carbonyl compounds and transfer dehydrogenations of alcohols were explored and compared to those of the well-established [2,5-(SiMe3)2-3,4-(CH2)4(η4-C4C═O)]Fe(CO)3 (3). A new compound, [2,5-bis(3,5-dimethylphenyl)-3,4-diphenylcyclopentadienone]iron tricarbonyl (7), was the most active catalyst in both transfer hydrogenations and dehydrogenations, and compound 3 was the least active catalyst in transfer hydrogenations. Evidence was found for product inhibition of both 3 and 7 in a transfer dehydrogenation reaction, with the activity of 3 being more heavily affected. A monomeric iron hydride derived from 7 was spectroscopically observed during a …

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 …

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 …

Assembling Of Niox/Mwcnts-Gc Anodic Nanocatalyst For Water Electrolysis Applications, Islam M. Al-Akraa Dr., Yaser M. Asal Mr, Saher D. Khamis Eng

Chemical Engineering

Glassy carbon (GC) electrode is intended to be modified with nickel oxide (NiOx) and multiwalled carbon nanotubes (MWCNTs) in the anodic reaction of water electrolysis. NiOx deposition time is optimized and a 5 min was enough to attain the maximum activity. A further modification of the catalyst with MWCNTs could greatly enhance its stability during continuous electrolysis. As an outcome, an energy amount of 21.7 kWh/KgO2 is minimized. Several electrochemical and materials characterization setups will be utilized to test the catalyst activity and to know its geometry and structure.

Bimetallic Complexes: The Fundamental Aspects Of Metal-Metal Interactions, Ligand Sterics And Application, Michael Bernard Pastor

University of the Pacific Theses and Dissertations

Metal containing complexes have been used to catalyze various organic transformations for the past few decades. The success of several mononuclear catalysts led to transition metal catalysts used in pharmaceuticals, environmental, and industrial processes. While mononuclear complexes have been used extensively, bimetallic systems have received far less attention. Bimetallic or polynuclear sites are commonly found in metalloenzymes that perform elegant transformation in biological systems, underlying their significance. Inorganic chemists take inspiration from nature and design model bimetallic complexes to further study this cooperativity effect. A bimetallic platform offers many structural and functional differences such as the identity of the metal …

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 …

Controlled Electrochemical Reduction Of Gold And Palladium Metal Precursors In Polyaniline, Nicole Goodwin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Polyaniline (PANI) has been extensively studied due to its unique electrochemical properties. The conjugated polymer is conductive with high chemical stability below 100°C, mechanical strength, and large surface area. The applications of PANI have included chemical sensing, corrosion inhibition coatings, light emitting diode and as a substrate for metal composite catalysts. Both chemical and electrochemical methods have been developed and utilized in the synthesis of PANI/metal composites. The simultaneous reduction of aniline and metal precursor produces a composite of PANI encapsulated metal, reducing the active surface area available for catalysis. Alternatively, chemical reduction of the metal precursor into preformed PANI …

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 …