Organic Chemistry Commons^™

Synthesis Of Dicamba Glucosides For The Study Of Environmental Dicamba Drift Effects On Soybeans, Holly Wallace

Theses and Dissertations

The most popular herbicide used for weed control has been glyphosate for many years in the Midwestern United States. Plants have begun to develop a resistance to glyphosate due to over use of the herbicide. This herbicide resistance has pushed farmers to turn to alternative herbicides such as dicamba and 2,4-D. Recently agrochemical companies have developed genetically modified crops that are resistant to herbicides such as dicamba. These modified crops allow farmers to spray their fields with dicamba without fear of crop damage. Farmers of non-genetically modified crops, however, suffer damage and loss of yield from herbicide drift effects ...

An Overview Of Dynamic Heterogeneous Oxidations In The Troposphere, Elizabeth A. Pillar-Little, Marcelo I. Guzman

Chemistry Faculty Publications

Due to the adverse effect of atmospheric aerosols on public health and their ability to affect climate, extensive research has been undertaken in recent decades to understand their sources and sinks, as well as to study their physical and chemical properties. Atmospheric aerosols are important players in the Earth’s radiative budget, affecting incoming and outgoing solar radiation through absorption and scattering by direct and indirect means. While the cooling properties of pure inorganic aerosols are relatively well understood, the impact of organic aerosols on the radiative budget is unclear. Additionally, organic aerosols are transformed through chemical reactions during atmospheric ...

Archean Phosphorus Liberation Induced By Iron Redox Geochemistry, Barry Herschy, Sae Jung Chang, Ruth Blake, Aivo Lepland, Heather Abbott-Lyon, Jacqueline Sampson, Zachary Atlas, Terence P. Kee, Matthew A. Pasek

Faculty Publications

The element phosphorus (P) is central to ecosystem growth and is proposed to be a limiting nutrient for life. The Archean ocean may have been strongly phosphorus-limited due to the selective binding of phosphate to iron oxyhydroxide. Here we report a new route to solubilizing phosphorus in the ancient oceans: reduction of phosphate to phosphite by iron(II) at low (<200 >°C) diagenetic temperatures. Reduction of phosphate to phosphite was likely widespread in the Archean, as the reaction occurs rapidly and is demonstrated from thermochemical modeling, experimental analogs, and detection of phosphite in early Archean rocks. We further demonstrate that the ...

A Stereospecific Pd-Catalyzed Suzuki Cross-Coupling Reaction And A Statistical Study Of The Ligand's Role In Stereoselection, Shibin Zhao

All Dissertations, Theses, and Capstone Projects

The development of palladium-catalyzed carbon-carbon cross-coupling reactions has profoundly influenced the manner through which we approach the synthesis of complex organic molecules. Among established cross-coupling reactions, which include Kumada, Negishi, and Stille reactions, the Suzuki cross-coupling reaction exhibits particularly wide functional group compatibility, while employing non-toxic, air-stable organoboron nucleophiles. Conventional studies of Pd-catalyzed Suzuki cross-coupling reactions have focused on C(sp²)-C(sp²) cross-coupling reactions, which result in the formation of planar products. Conceptually, the use of C(sp³) (secondary) nucleophiles would enable the reliable manipulation of organic molecules in three dimensions. However, this process has not ...

Synthesis And Evaluation Of Densely-Functionalized Troponoids, Danielle R. Hirsch

All Dissertations, Theses, and Capstone Projects

Herein, we document our efforts to expand the scope of troponoid synthetic methodology towards densely-substituted scaffolds. This body of work has focused primarily on an oxidopyrylium cycloaddition/ring-opening strategy for the synthesis and biochemical evaluation of troponoids for assistance in a variety of medicinal chemistry studies. In Chapter 1, we outline the use of this synthetic strategy in the profiling of a library of synthetic αHTs against an aminoglycoside antibiotic resistance enzyme known as aminoglycoside-2’’-O-nucleotidyltransferase [ANT(2’’)-Ia]. Enzymatic mechanistic insights have been gleaned from an assessment of troponoid/antibiotic synergistic potential. In particular, two synthetic constructs were identified ...

The Development Of Metal Complexes As Components Of Fluorescent And Nuclear Imaging Probes, William Turnbull

Electronic Thesis and Dissertation Repository

The advent of molecular imaging as a discipline has drastically improved our ability to understand the biochemical and cellular events that drive life, death and disease. This thesis will document the discovery of new metal chelators for Re/^99mTc, new methods of incorporating these metals into peptide structures, as well as new fluorescent compounds. These novel methods and compounds may be used in the development of molecular imaging probes for single photon emission computed tomography (SPECT) and optical imaging techniques, with applications for differentiating cancerous tissue from benign and healthy.

Chapter 2 discusses the development of a dual modality ...

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 ...

Thienoisatin Oligomers As N-Type Molecular Semiconductors, Natalie M. Kadlubowski, Xuyi Luo, Jianguo Mei

The Summer Undergraduate Research Fellowship (SURF) Symposium

Organic field effect transistors (OFETs) offer many advantages compared to traditional inorganic transistors, such as flexibility and solution processability. In this study we design and synthesize two thienoisatin-based organic semiconducting small molecules, then investigate their electronic properties in n-type OFETs. To introduce n-type charge transport, electron-withdrawing dicarbonitrile moieties were installed on thienoisoindigo and bis-thienoisatin molecules, which led to a quinoidal conjugation on thienoisoindigo, while maintaining an aromatic conjugation on the bis-thienoisatin. Following the syntheses, the molecules were characterized to determine highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels via cyclic voltammetry, as well as any potential ...

Safe Use Of Hydrogen Peroxide In The Organic Lab, Patrick Dussault

Organic Peroxides: Safety Issues

The article describes good practices for use of hydrogen peroxide (H₂O₂) in an organic lab setting. Major headings include:

Leading references; Toxicity; Physical properties; Chemical properties; Stability and incompatibilities; Confinement/pressure; and, References to accidents involving H₂O₂.

Alkene Ozonolysis In The Academic Lab, Patrick Dussault

Organic Peroxides: Safety Issues

The following information is offered as a guide based upon our experience with application of ozone for organic oxidations and hydroperoxide synthesis. Please send suggestions, requests, or corrections to pdussault1@unl.edu.

Introduction and leading references

Overview of ozonolysis: Mechanism, Substrate reactivity, Typical reaction conditions, Reaction monitoring, Reaction work-ups

Safety Issues

Acknowledgements:

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The following provides a brief introduction to the application of ozonolysis within academic labs. Ozonolysis remains among the most frequently used of methods for oxidative cleavage of alkenes. While best known as a means by which to introduce aldehydes and ketones, ozonolysis can also be used to generate ...

Synthesis, Characterization, And Applications Of Ammonium/Phosphonium Chitosan Derivatives For Investigative Dna Interactions, Quinton Kirk Wyatt

MSU Graduate Theses

Chitosan is examined as a non-viral vector capable of efficient gene delivery due to its favorable properties such as biodegradability, biocompatibility, and is non-toxic to mammalian cells. Cell modifications and vector permeability are enhanced in non-viral vectors that incorporate electrostatic interactions. This work synthesizes cationic (N⁺, P⁺) chitosan derivatives, to enhance electrostatic interactions towards nucleotides, using amide coupling agents EDC and HOBt. The final chitosan derivatives will bear cationic functional groups (N⁺, P⁺) with various alkyl groups (Me, Et, Pr, Ph) to examine their affinities to nucleotides and antifungal properties. mPEG grafted cationic chitosan derivatives were also synthesized to examine ...

Nmr Spectroscopic Properties Of Nucleotides, And A New Method Of Numeric Calculation Of Raman Intensities For Organic Molecules, William R. Ehrhardt

MSU Graduate Theses

General and accurate computational methodologies are currently lacking for large chemical systems. This is primarily due to the computational expense required to perform calculations on systems with one hundred or more atoms. Calculated spectroscopic properties could aid in the process of elucidating structural features of large biologically relevant molecules if accurate and inexpensive methods are developed. Towards this end the first steps were taken to design a general methodology for predicting NMR chemical shifts of large nucleic acid systems. It was found that HF and semi-empirical methods were not sufficient for optimization of nucleobases, and therefore larger nucleotide or nucleic ...

Conformationally-Controlled Late-Stage Modifications For Sar Studies Of The C-3-Glcp Moiety Of Ipomoeassin F, Lucas Whisenhunt

Theses and Dissertations

The resin glycoside, ipomoeassin F has been shown to be extremely potent against multiple cancer lines (IC50 = 4.2-36 nM). However, the mechanism of action of this potent and complex natural product is still not fully understood. The α,β-unsaturated esters of the glucosyl moiety have been shown to be vital for the overall cytotoxicity of ipomoeassin F. Nevertheless, the importance of the tigloyl ester of the glucosyl moiety is still largely unknown. This work aimed to study the pharmacophore importance of the tigloyl ester by creating, an efficient, scalable, and flexible synthesis route for various analogs. The 18-linear step ...

Chemical Strategies For Drug Development Of Fucose-Truncated Ipomoeassin F Analogues, Melissa Hirsch

Theses and Dissertations

Natural product synthesis has many applications in the field of chemical biology, due to the protein binding affinity to the complex three-dimensional structure. However, synthetic and structure-activity relationship studies concerning certain drug targets are scarce. For example, members of the ipomoeassin family have exhibited anti-cancer properties, but cost-effective optimization of these compounds has not yet been extensively studied. Ipomoeassin F, a natural glycoresin isolated from the leaves of the Ipomoea squamosa plant in the Suriname rainforest, has shown high cytotoxicity, with IC50 values measured at the low nanomolar range. Two studies by Postema and Fuerstner have outlined synthesis pathways for ...

Working With Organic Peroxides In The Academic Lab, Patrick Dussault

Organic Peroxides: Safety Issues

ABSTRACT: The following is a brief introduction to peroxide safety from the viewpoint of a synthetic chemist. Major topics include: classes of organic peroxides; peroxide reactivity; hazard identification and minimization; reaction monitoring; and, hazards associated with auto-oxidation of peroxidizable solvents.

KEYWORDS: peroxide, hydroperoxide, hydroperoxyacetal, ozonide, perester, dihydroperoxide, monoperoxyacetal, active oxygen, peroxide strips, TLC indicator, self-accelerating decomposition, radical, exothermicity, transition metals.

CONTENTS: 1. Literature resources 2. Major classes of peroxides 3. Basis for peroxide reactivity 4. Determining reactivity and minimizing hazards a. Steps to take before an experiment b. Minimizing hazard during reactions c. Monitoring reactions d. Working with isolated peroxides ...

Open Resonance Assisted Hydrogen Bonds And Competing Quasiaromaticity, Yen H. Nguyen, Bryan J. Lampkin, Amrit Venkatesh, Arkady Ellern, Aaron J. Rossini, Brett Vanveller

Chemistry Publications

The delocalization of electron density upon tautomerization of a proton across a conjugated bridge can alter the strength of hydrogen bonds. This effect has been dubbed resonance-assisted hydrogen bonding (RAHB) and plays a major role in the energetics of the tautomeric equilibrium. The goal of this work was to investigate the role that π-delocalization plays in the stability of RAHBs by engaging other isomerization processes. Similarly, acid-base chemistry has received little experimental attention in studies of RAHB and we address the role that acid-base effects play in the tautomeric equilibrium. We find that π-delocalization and the disruption of adjacent aromatic ...

Investigation Of Vaporization Enthalpies And Vapor Pressures Of Organic Compounds By Correlation Gas Chromatography, Carissa Nelson

Dissertations

Thermodynamic properties of organic compounds are useful to scientists and manufacturers in many areas of research and technology. This work focuses on measuring and reporting these properties on materials of commercial, environmental and scientific interest. Vaporization enthalpies and vapor pressures of several organic compounds have been studied using correlation gas chromatography (CGC) and are reported here as well as in recent publications. The CGC method allows for the indirect measurement of these properties in instances where these materials are available only in mixtures or in very small amounts.

The qualities of these measurements for any chosen target are directly related ...

Catalytic Functionalization Of Organoaluminum Reagents And Olefins By Cross-Coupling With Copper And Nickel, Bijay Shrestha

Chemistry ETDs

This thesis is divided into two parts. The first part focuses on the Cu-catalyzed cross-coupling of organoaluminum reagents with organohalides. One of the most powerful tools for the construction of C-C bonds is cross-coupling. But, this reaction is predominantly catalyzed by Pd, a rare and expensive transition metal, which inevitably makes the process unsustainable in the long-term. Furthermore, Pd-catalyzed cross-coupling also shows low tolerance for alkyl and heteroaryl substrates because of β-hydride elimination and catalyst deactivation, respectively. Although these issues remain largely solved by using sterically hindered and electron-rich ligands, however making these types of ligands is synthetically challenging and ...

Visible Light Generation Of High-Valent Corrole-Manganese(V)-Oxo Intermediates And Biomimetic Studies Of The Oxidation Of Organic Sulfides Catalyzed By Manganese Corroles With Iodobenzene Diacetate, Davis Ray Ranburger

Masters Theses & Specialist Projects

High-valent transition metal-oxo intermediates play essential roles as active oxidizing species in enzymatic and biomimetic catalytic systems. Extensive research has been conducted on a variety of transition metal catalysts being studied as models for the ubiquitous cytochrome P450 enzymes. In doing so, the production of enzyme-like oxidation catalysts and probing studies on the sophisticated oxygen atom transfer mechanism are taking place.

In this work, visible-light irradiation of highly-photo-labile corrole-manganese(IV) bromates and chlorates was studied in two corrole systems with differing electronic environments, i.e. 5,10,15-trisphenylcorrole (H3TPC) and 5,10,15- tris(pentafluorophenyl)corrole (H3TPFC). In ...

Photochemical Investigation Of High-Valent Metal-Oxo Intermediates Containing Corrole And Light-Harvesting Porphyrin Ligands, Jonathan Malone

Masters Theses & Specialist Projects

In enzymatic and synthetic catalytic oxidations, high-valent iron-oxo intermediates play a vital role as the active oxidant. In this regard, many synthetic metal catalysts are designed as biomimetic models to resemble the active site of Cytochrome P450 enzymes (P450) which are the predominant oxidation catalysts in nature. Vitamin B12 cofactors, with a corrole-like structure corrin, are also utilized in some of the more difficult reactions in nature such as rearrangement and reductase reactions.

In this work, application of the promising photochemical method to corrolecontaining ligands systems showed much success in the generation of manganese(V)-oxo corrole intermediates using two ...