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Full-Text Articles in Physical Sciences and Mathematics
Greening Of Catalytic Processes Using First-Row Transition Metals For Atom Transfer Radical Addition And Transfer Hydrogenation, Gabrielle Pros
Greening Of Catalytic Processes Using First-Row Transition Metals For Atom Transfer Radical Addition And Transfer Hydrogenation, Gabrielle Pros
Electronic Theses and Dissertations
This work focused on “greening” catalytic processes, atom transfer radical addition (ATRA), which adds an alkyl halide across and alkene, and transfer hydrogenation/dehydrogenation, which reduces a carbonyl without needing direct H2 gas. Part of “greening” of these processes is through using abundant first row metals, Cu and Ni for catalysis. One aim was to design new ligands which would be more active in these systems; the second was investigation of additives for catalyst regeneration to reduce the catalyst loading necessary for high yields.
The TPMA* family was investigated in ATRA. Rate constants followed the expected trend, which increased …
C-Metalated Nitriles: Diastereoselective Alkylations And Arylations, Robert John Mycka
C-Metalated Nitriles: Diastereoselective Alkylations And Arylations, Robert John Mycka
Electronic Theses and Dissertations
Development of an sp3 hybridized halogen-magnesium exchange route to Grignard reagents, chelation-controlled asymmetric induction of γ- and δ-hydroxynitriles as well as a diastereoselective arylation procedure for C-zincated nitriles have been explored. Sequential addition of i-PrMgCl and n-BuLi to 3- and 4-carbon iodoalcohols triggers a facile halogen-metal exchange to generate cyclic magnesium alkoxides capable of intercepting electrophiles to produce a diverse range of substituted alcohols. This work advances progress toward the synthesis of highly desirable chiral Grignard reagents.
Double deprotonation of γ- and δ-acyclic hydroxynitriles with i-PrMgCl effects highly diastereoselective alkylations via a singly-chelated magnesiated nitriles. …
Design And Applications Of Charge-Separated Metal-Organic Frameworks, Sheela Thapa
Design And Applications Of Charge-Separated Metal-Organic Frameworks, Sheela Thapa
Chemistry and Chemical Biology ETDs
Ionic tetrapodal ligands with colinear coordinating arms are very effective for designing hybrid porous materials with unusual structure and properties. The novelty of this research work lies in the utilization of a unique borate ligand that leads to charge-separated MOF structure with tailor designed properties. Borate ligands being tetrahedral afford 3D materials and the negative charge of borate anion can compensate the positive charge of metal ion in the framework. The borate ligands designed in this research consists of quaternary ammonium cation and anionic borate with four pyridine arms. These ligands upon coordination with Cu(I), Cu(II), Ag(I) and Co(II) metal …
The Alpha-Activator Complex, Cellular Maturation, And Catalytic Mechanism Of Iron-Type Nitrile Hydratase, Wasantha Lankathilaka Karunagala Pathiranage
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
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 …
Synthesis And Characterization Of A Homogeneous Cobalt Catalyst For The Hydrogenation Of Acetone To Isopropanol, Joselyn G. Molina
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
Oxidative C–C And C–Heteroatom Reactivity Of High-Valent Nickel Complexes, Sofia Marie Smith
Arts & Sciences Electronic Theses and Dissertations
ABSTRACT OF THE DISSERTATION
Oxidative C–C and C–Heteroatom Reactivity of High-Valent Nickel Complexes
by
Sofia M. Smith
Doctor of Philosophy in Chemistry
Washington University in St. Louis, 2019
Professor Liviu M. Mirica, Chair
Professor Kevin D. Moeller, Co-Chair
Nickel 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 …
Nontraditional Hydrogen Bonding In Asymmetric Lewis Acid Catalysis, Brandon Vernier
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
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
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 …
Mechanochemically Synthesized Cobalt Oxide-Based Particles For The Reduction Of Nitrophenols And Impacting Factors To Its Mechanism, Lorianne R. Shultz
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 …
Nucleophilic Phosphine Addition: Exploration Of Novel Alkyne Transformations, Brett Pierce
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, …
Engineering High Reaction Economy Or, An Intensification/Scoring Program For The Preparation Of Simple And Complex Molecules, Caleb J. Kong
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 …
New Synthetic Methods Using Superelectrophiles, Sean Kennedy
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 …