An Investigation Of Alkylboron Transmetallation In Palladium-Catalyzed Suzuki Reactions,
2019
CUNY Graduate Center
An Investigation Of Alkylboron Transmetallation In Palladium-Catalyzed Suzuki Reactions, Benjamin Murray
Dissertations, Theses, and Capstone Projects
Through the past 40 years, carbon-carbon cross-coupling reactions have greatly enhanced the ability of chemists to synthesize C(sp2)-C(sp2) bonds and more recently C(sp2)-C(sp3) bonds. In particular, the Suzuki reaction has proven to be invaluable with its high yields, good functional group tolerance, and low toxicity of reagents. One of the component steps of the catalytic cycle of this reaction is transmetallation, in which the nucleophilic species transfers its organic component to the metal center (generally palladium). The mechanism of transfer from primary alkylboron nucleophiles was studied in the 1990's via use of …
Bridging The Molecular/Material Divide: An Investigation Into The Properties Of Polyesters,
2019
University of Rhode Island
Bridging The Molecular/Material Divide: An Investigation Into The Properties Of Polyesters, Terra Marie M. Jouaneh
Senior Honors Projects
By definition, polymers consist of large molecules composed of small, repeating units called monomers. These monomers give characteristic material properties to polymers, whether they be the melting point, the folding character, or the inherent stability. Many of the objects we encounter on a daily basis are composed of polymers. These polymers may be synthetic, such as the plastic in disposable bags, or natural, like glycogen in the liver. Recent developments in biotechnology have used synthetic polymers in drug delivery, contact lenses, and even organ transplants. Polyesters, in particular, have been utilized pharmacologically due to their biodegradable properties. Understandably, not all …
Heavy-Atom Tunneling In The Planar Bond Shifting Of [16]Annulene,
2019
The University of San Francisco
Heavy-Atom Tunneling In The Planar Bond Shifting Of [16]Annulene, Philip Lampkin, Jon Shezaf
Creative Activity and Research Day - CARD
Mid-sized annulenes are known to undergo rapid π-bond shifting. Given that heavyatom tunneling plays a role in planar bond shifting of cyclobutadiene, we computationally explored the contribution of heavy atom tunneling to the planar bond shifting in the major (CTCTCTCT) and minor (CTCTTCTT) isomers of [16]annulene. (U)M06-2X/cc-pVDZ calculations yield bond-shifting barriers of ca. 10 kcal/mol. The results also reveal extremely narrow barrier widths, suggesting a high probability of tunneling for these bond-shifting reactions. Rate constants were calculated using canonical variational transition state theory (CVT) as well as with small curvature tunneling (SCT) contributions, via direct dynamics. For the major isomer, …
Assessment Of Oxidative Stress In The Livers Of Rats Exposed To 2-Aminoanthracene For Twelve Weeks,
2019
Georgia Southern University
Assessment Of Oxidative Stress In The Livers Of Rats Exposed To 2-Aminoanthracene For Twelve Weeks, John C. Stagg
Honors College Theses
Diabetes is a chronic illness that affects many people, and it’s thought that environmental exposure to certain compounds may increase its proliferation. In this study, we examine the dietary effects of 2-aminoanthracene (2AA), a polycyclic aromatic hydrocarbon (PAH), in rats, specifically as it relates to oxidative stress. Oxidative stress refers to the imbalance of reactive oxygen species (ROS) and antioxidants in living systems; it has been shown to contribute to type-1 diabetes. To accomplish the study objectives rats were divided into three dietary treatment groups, control (0 mg/kg-2AA), low dose (50 mg/kg-2AA) and high dose (100 mg/kg-2AA). Rats were fed …
Best Organic Chemistry Practices In The Midwest,
2019
Western Michigan University
Best Organic Chemistry Practices In The Midwest, Claire Van Der Bosch
Honors Theses
Organic Chemistry is a gateway course to a handful of courses in higher chemical education. Unfortunately, it is notorious for its high-fail, high-withdrawal, and high-drop rate and has a reputation for being time-consuming, with difficult concepts that are oftentimes new to students. It is often taught in a two-semester sequence, with the courses named Organic I and Organic II, and both courses have a lab component. At Western Michigan University, the fail rate for these two courses are 53.5% and 36.9%, respectively. Most higher education institutions are certified with the American Chemical Society (ACS) and given a skeleton of a …
Mechanistic Studies And Derivative Effects In 1, 3, 4- Oxadiazole Synthesis Via Cyclodehydration Reactions,
2019
Otterbein University
Mechanistic Studies And Derivative Effects In 1, 3, 4- Oxadiazole Synthesis Via Cyclodehydration Reactions, Evan Huggins
Undergraduate Honors Thesis Projects
In the world of pharmaceutical synthesis, research to combat foreign pathogens is always necessary. Scientists have been exploring different methods in order to synthesize the most effective compounds in antibacterial, anticancer, anti-inflammatory, and many other treatments. A key component within these versatile compounds are 1,3,4-oxadiazoles. Current methods to synthesize these compounds are inefficient. This research seeks to improve oxadiazole synthesis; however, the mechanism of this reaction is unknown. The goal of this project was to study the mechanistic pathway in the discovered, one-pot cyclodehydration synthesis of 1,3,4-oxadiazoles. In the first part of this study, a diacylhydrazine intermediate was proposed. This …
Analysis Of Dl-Amino Acid Ratios In Eggshells Using Reverse Phase-High Pressure Liquid Chromatography,
2019
Andrews University
Analysis Of Dl-Amino Acid Ratios In Eggshells Using Reverse Phase-High Pressure Liquid Chromatography, Gergana Milkova
Honors Theses
HPLC methodology was developed to determine the concentrations and ratios of D to L amino acids in emu and ostrich eggshells treated with heat at different temperatures . We aimed to determine an internal standard and how ratios were affected under different conditions. An HPLC method was determined that gave consistent retention times and satisfactory enantioseparation . Calibration curves for each amino acid were developed from single and multi-amino acid containing dilution series producing a model that most closely replicates the eggshell-extracted amino acids.
Application Of The Picoloyl Group In Carbohydrate Chemistry,
2019
University of Missouri-St. Louis
Application Of The Picoloyl Group In Carbohydrate Chemistry, Michael Mannino
Dissertations
Stereocontrol of glycosylation reactions is a constant struggle in the field of synthetic carbohydrate chemistry. The application of the picoloyl (Pico) substituent can offer numerous stereocontrolling avenues. The most popular application is the Hydrogen-bond-mediated Aglycone Delivery (HAD) method that provides excellent selectivity in the glycosylation of a variety of sugar substrates. The HAD method relies on the formation of an intermolecular hydrogen bond between the nitrogen atom of the Pico substituent on the glycosyl donor with the hydroxyl group of the glycosyl acceptor. This interaction provides a facial preference for the nucleophilic attack and hence provides powerful stereocontrol for the …
Enantioselective Copper Catalyzed Alkyne-Azide Cycloaddition By Dynamic Kinetic Resolution,
2019
Missouri University of Science and Technology
Enantioselective Copper Catalyzed Alkyne-Azide Cycloaddition By Dynamic Kinetic Resolution, En Chih Liu, Joseph J. Topczewski
Chemistry Faculty Research & Creative Works
The copper(I) catalyzed alkyne-azide cycloaddition (CuAAC), a click reaction, is one of the most powerful catalytic reactions developed during the last two decades. Conducting CuAAC enantioselectively would add a third dimension to this reaction and would enable the direct synthesis of α-chiral triazoles. Doing so is demanding because the two precursors have linear geometries, and the triazole product is a flat heterocycle. Designing a chiral catalyst is further complicated by the complex mechanism of CuAAC. We report an enantioselective CuAAC (E-CuAAC), enabled by dynamic kinetic resolution (DKR). The E-CuAAC is high yielding and affords up to 99:1 er. The E-CuAAC …
Drug Improvement And Design Involving G-Protein Coupled Receptors,
2019
Taylor University
Drug Improvement And Design Involving G-Protein Coupled Receptors, Gabriel Saliba
Chemistry & Biochemistry Student Projects
No abstract provided.
A Chemical Overview Of Opioid Receptors And Their Agonists,
2019
Taylor University
A Chemical Overview Of Opioid Receptors And Their Agonists, Noah Kuszak
Chemistry & Biochemistry Student Projects
This work is a brief overview of the three main opioid receptors and some current research of the ways we can change the agonists and how they affect the opioid receptor pathway.
Dentin Biomodification Potency Of Proanthocyanidins,
2019
Taylor University
Dentin Biomodification Potency Of Proanthocyanidins, David J. Ryker
Chemistry & Biochemistry Student Projects
No abstract provided.
An Improved Synthesis Of Adefovir And Related Analogues,
2019
Department of Physical Sciences, Cork Institute of Technology, Cork, Ireland
An Improved Synthesis Of Adefovir And Related Analogues, Timothy P. O'Sullivan, Et Al
Physical Sciences Publications
An improved synthesis of the antiviral drug adefovir is presented. Problems associated with current routes to adefovir include capricious yields and a reliance on problematic reagents and solvents, such as magnesium tert-butoxide and DMF, to achieve high conversions to the target. A systematic study within our laboratory led to the identification of an iodide reagent which affords higher yields than previous approaches and allows for reactions to be conducted up to 10 g in scale under milder conditions. The use of a novel tetrabutylammonium salt of adenine facilitates alkylations in solvents other than DMF. Additionally, we have investigated how …
Synthesis And Metalation Of Internally Alkylated Porphyrinoids,
2019
Illinois State University
Synthesis And Metalation Of Internally Alkylated Porphyrinoids, Alissa Nicole Latham
Theses and Dissertations
The mechanism behind alkyl migration in palladium(II) benzocarbaporphyrins was investigated through the synthesis of a 23-methylcarbaporphyrin. It was found that palladium insertion led to methyl group migration to C21 and it is proposed that this occurs through an oxidative addition onto the palladium metal center, followed by a reductive elimination to transfer the methyl to the internal carbon. A similar rearrangement was observed when 23-methylcarbaporphyrin was reacted with [Rh(CO)2Cl]2 and resulted in the formation of a rhodium(III) complex containing a three-membered rhodacycle. The syntheses of rhodium(I) and rhodium(III) derivatives of other carbaporphyrins, including 21- and 22-methylbenzo-carbaporphyrins, were probed and four …
The Effects Of Reactant Concentration And Air Flow Rate In The Consumption Of Dissolved O2 During The Photochemistry Of Aqueous Pyruvic Acid,
2019
University of Kentucky
The Effects Of Reactant Concentration And Air Flow Rate In The Consumption Of Dissolved O2 During The Photochemistry Of Aqueous Pyruvic Acid, Alexis J. Eugene, Marcelo I. Guzman
Chemistry Faculty Publications
The sunlight photochemistry of the organic chromophore pyruvic acid (PA) in water generates ketyl and acetyl radicals that contribute to the production and processing of atmospheric aerosols. The photochemical mechanism is highly sensitive to dissolved oxygen content, [O2(aq)], among other environmental conditions. Thus, herein we investigate the photolysis (λ ≥ 305 nm) of 10–200 mM PA at pH 1.0 in water covering the relevant range 0 ≤ [O2(aq)] ≤ 1.3 mM. The rapid consumption of dissolved oxygen by the intermediate photolytic radicals is monitored in real time with a dissolved oxygen electrode. …
Synthesis Of A Sulfur Variant For Treatment Of Trypanosomiasis,
2019
University of Nebraska at Omaha
Synthesis Of A Sulfur Variant For Treatment Of Trypanosomiasis, Carlos Vera-Esquivel
UNO Student Research and Creative Activity Fair
Previous work in our lab has found diphenyl ether benzylamines showed a successful response with a micromolar concentration of our lead compound to treat the deadly Trypanosamiosis rhodesience. Furthermore, mammalian cell lines saw promising resistance towards damages. The goal of this study was to synthesize a diphenyl thio benzylamine variant. This variant was more active toward T. b. rhodesience but showed more toxicity to both rat 10 (IC50 mM) and human cell lines (HFF, HC-04, U-2 OS, and HEK293). The selectivity index (ratio of toxicity to activity in the same concentration units (SI)) …
Facile And Efficient Synthesis Of Thiosemicarbazone Derivatives With Functionalized Pendant Amines.,
2019
University of Louisville
Facile And Efficient Synthesis Of Thiosemicarbazone Derivatives With Functionalized Pendant Amines., Anna E Davis
College of Arts & Sciences Senior Theses
Bis-thiosemicarbazones are an important class of ligands for the synthesis of transition metal complexes with applications in medicine and electrochemistry.1,2 Among the most studied of these complexation ligands is diacetyl-2,3-bis(N4-methyl-3-thiosemicarbazone) (denoted as ATSM, 1, Figure 1).2,3 Derivatives of 1 with various amines in place of the methylamine of ATSM have previously been reported, including diacetyl (N4-methylthiosemicarbazone-N4′-dimethylthio-semicarbazone) (denoted as ATSM/DM, 2).4 In this work, we pursue the development of a library of ATSM derivatives with a variety of functionalized pendant amines with a range of electronic and steric …
Seasonal Origins Of Soil Water Used By Trees,
2019
ETH Zurich
Seasonal Origins Of Soil Water Used By Trees, Scott T. Allen, James W. Kirchner, Sabine Braun, Rolf T. W. Siegwolf, Gregory R. Goldsmith
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Rain recharges soil water storages and either percolates downward into aquifers and streams or is returned to the atmosphere through evapotranspiration. Although it is commonly assumed that summer rainfall recharges plant-available water during the growing season, the seasonal origins of water used by plants have not been systematically explored. We characterize the seasonal origins of waters in soils and trees by comparing their midsummer isotopic signatures (δ2H) to seasonal isotopic cycles in precipitation, using a new seasonal origin index. Across 182 Swiss forest sites, xylem water isotopic signatures show that summer rain was not the predominant water source …
Metal-Assisted Hydrolysis Reactions Involving Lipids: A Review,
2019
University of Richmond
Metal-Assisted Hydrolysis Reactions Involving Lipids: A Review, Dominique E. Williams, Kathryn B. Grant
Chemistry Faculty Publications
This report covers major advances in the use of metal ions and complexes to hydrolyze ester and phosphate ester lipid bonds. These metal-based Lewis acids have been investigated as catalysts to isolate fatty acids from biological sources, as probes to study phospholipid bilayer properties, as tools to examine signal transduction pathways, and as lead compounds toward the discovery of therapeutic agents. Metal ions that accelerate phosphate ester hydrolysis under mild conditions of temperature and pH may have the potential to mimic phospholipase activity in biochemical applications.
Metrics And Methods Used To Compare Student Performance Data In Chemistry Education Research Articles,
2019
University of Washington - Seattle Campus
Metrics And Methods Used To Compare Student Performance Data In Chemistry Education Research Articles, Michael R. Mack, Cory Hensen, Jack Barbera
Chemistry Faculty Publications and Presentations
Quasi-experiments are common in studies that estimate the effect of instructional interventions on student performance outcomes. In this type of research, the nature of the experimental design, the choice in assessment, the selection of comparison groups, and the statistical methods used to analyze the comparison data dictate the validity of causal inferences. Therefore, gathering and reporting validity evidence in causal studies is of utmost importance, especially when conclusions have real policy implications for students and faculty, among other stakeholders. This review examines 24 articles that reported quantitative investigations of the effect of instructional interventions on performance-based outcomes conducted within undergraduate …
