Chemistry Commons^™

A Lab To Stemulate Undergraduate Students Into Science, Technology, Engineering And Mathematics Majors, Nicole Lynn Speelman

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The central focus is the development and implementation of a research/lab module for first year chemistry courses. Electrochemical techniques are utilized to study oxidation and reduction reactions of neurotransmitters with a poly(2,2'-Bithiophene) modified electrode. The goal is to excite students about chemistry and encourage them to continue studies in Science, Technology, Engineering, and Mathematics (STEM) during their undergraduate education. The lab module was created for Project REEL (Research Experiences to Enhance Learning) and will be illustrated with results typically obtained by students. The experiment is inquiry-based, which includes challenging questions students have to do collaboration and research to answer, as …

A Comparison Of Physical And Electrochemical Properties Of Two Ionic Liquids Containing Different Cations: 1-Butyl-1-Methyl-Pyrrolidinium Beti And 1-Butyl-3-Methyl-Imidazolium Beti, Edward Nelson Kennedy

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A novel ionic liquid, 1,1-butyl-methyl-pyrollidinium bis-pentafluoroehthanesulfonylamide (BMPyrrBeti) was synthesized and characterized. Its physical and electrochemical properties compared to a similar ionic liquid containing the imidazolium cation, 1-methyl-3-butyl-imidizolium bis-pentafluoroehthanesulfonylamide (BMImBeti). The two ionic liquids contain the same anion, bis((pentafluoroethane)sulfonyl)imide (Beti), and the same two alkly group substituents (a methyl and a butyl group). The two ionic liquids differ only by the cation component, and the connectivity of the two substituents (1,1 for the former, and 1,3 for the latter).

The following physical properties of BMPyrrBeti were measured and compared to the same properties of BMImBeti: conductivity, viscosity, absorption and desorption of …

Quantum Chemical Investigations Of Nucleophilic Aromatic Substitution Reactions And Acid Dissociations Of Aliphatic Carboxylic Acids, David Henry Schory

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Quantum chemical analysis was used to examine nucleophilic aromatic substitution reactions of fluorinated benzophenones, diphenyl sulfones, and triphenylphosphine oxides. Some experimental results for these compounds were contrary to conventional wisdom, which holds that calculated atomic charges for the aromatic sites and ¹³C-NMR and ¹⁹F-NMR chemical shifts should allow prediction of the preferred sites for aromatic substitution. Density functional theory (B3LYP/6-31+G*//RM1) and semi-empirical (RM1) quantum chemical calculations were employed to study the intermediates in the reaction pathways in order to identify the preferred paths for aromatic substitution. In most cases studied para substitution pathways had the lower energy intermediates …

Lithiation Reactions Of 3-(4-Chlorophenyl)Sydnone And 3-(4-Methylphenyl)Sydnone, Nigel Ngonidzashe Chitiyo

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Ortho-iodophenyl sydnones are key intermediates in Sonogashira coupling reactions and the resulting ortho alkynyl sydnones are useful precursors to functionalized sydnonquinolines. In this work, three synthetic routes leading to the synthesis of these versatile intermediates were explored.

Lithiation reactions of 3-(4-chlorophenyl) sydnone and 3-(4-methylphenyl) sydnone followed by trapping with iodine electrophiles yielded the expected disubstituted species 3-(4-chloro-2-iodophenyl)-4-iodosydnone and 3-(4-methyl-2-iodophenyl)-4-iodosydnone in yields ranging from 14% to 75%. Subsequent reduction with sodium sulfite removed the iodine at the C-4 position in both species yielding the ortho iodophenyl sydnones in 80% and 85% yield, respectively.

A surprising result was the discovery that careful …

Conducting Polymer Matrix Poly(2,2'-Bithiophene) Mercuric Metal Ion Incorporation, Rachel Michele Kingdom

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The synthesis of poly(2,2'bithiophene) was carried out utilizing the Epsilon 2000 cyclic voltammeter. In order to incorporate the mercuric ion into the polymer matrix, the polymer was grown on an Iridium Oxide conductive glass, immersed into a solution of 0.005M HgSO4 for 15 minutes. The mercuric ion became covalently bonded to the sulfur from the polymer. The comparison of the bare platinum electrode in a solution of 0.005M pyrocatechol to the modified poly(2,2'-bithiophene) polymer was ran at a scan rate of 100mVs-1. This gave a direct comparison of oxidation/reduction peak potentials. As seen, the modified poly(2,2'-bithiophene) polymer with the mercuric …

Tailoring The Degree Of Branching In Hyperbranched Poly (Arylene Ether Sulfone)S And Poly(Arylene Ether Ketone)S Prepared Via An A2 + Bb'b" Approach, Shravanthi Raghavapuram

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The synthesis and characterization of hyperbranched poly(arylene ether)s with tailored degrees of branching has been explored via an A₂+B₃ approach. The reactivity of the individual electrophilic sites towards nucleophilic aromatic substitution, NAS, of the BB'B" monomers 4, 3', 5'-trifluorophenyl sulfone, 1 and 4, 3', 5'-trifluoro benzophenone, 2 were studied. The concentration, temperature and solvent conditions had an effect on the degree of branching, DB, in 1 and 2 and were probed via ¹³C and ¹⁹F NMR spectroscopy as well as a series of model reactions employing p-cresol 16, which acts as the nucleophile. Soluble, …

Electronic To Vibrational Energy Transfer From Cl* (2P1/2) To Ch4 And Cd4, Brian R. Munson

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Electronic-to-vibrational (E-V) energy transfer is a significant kinetic channel in the collisional quenching of spin-orbit excited chlorine atoms, Cl^* (²P_1/2, 882 cm^-1), by molecular collision partners. In the present study Cl^* atoms are prepared in the presence of CH₄ or CD₄, under pseudo first-order conditions, by photolysis of ICl at 532 nm with a pulsed Nd:YAG laser. Quenching of Cl^* by CH₄ or CD₄ results in E-V excitation of the ν4 asymmetric bending mode as observed by infrared (IR) fluorescence from the vibrationally excited products. Time-resolved …

Cationic Exchange Reactions Involving Dilithium Phthalocyanine, Morgan M. Hart

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Dilithium phthalocyanine (Li₂Pc) consists of an aromatic macrocycle possessing a doubly negative charge and two Li⁺ counterions. One Li⁺ ion is easily displaceable while the other remains coordinated to the phthalocyanine ring. The displaceable Li⁺ cation can be exchanged with other cations, such as a singly charged tetra-alkyl ammonium cation, by using several variations of a general procedure. It has been demonstrated that tetraalkylammonium lithium phthalocyanines (TAA-LiPcs) can be successfully and reproducibly synthesized with yields ranging from 54.5% up to 64.3%. All TAA-LiPcs demonstrated poor solubilities from approximately <0.2 mg/mL to 5 mg/ml in the solvents tested (with the exception of tetrapropylammonium lithium phthalocyanine and tetrahexylammonium lithium phthalocyanine). All of the TAA-LiPcs synthesized were dark-purple in color, with the exception of tetraheptylammonium lithium phthalocyanine and tetraoctylammonium lithium phthalocyanine. These two compounds were dark - blue in color. Melting points varied greatly from >370.4°C to 157.9°C and depended greatly upon …

Comparison Of The Electrochemical Properties Of Ethanol In Perchloric Acid And Ionic Liquids, Sandra Felix-Balderrama

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1-Ethyl-3-Methylimidazolium Tetrafluroborate (EMImBF₄) and 1-Ethyl-3-Methylimidazlium Bis(trifluoromethanesulfonyl)imide (EMImTFSI) ionic liquids were synthesized and characterized in order to study the electrochemical oxidation of ethanol in these ionic liquids on a platinum surface electrode.

It was found that pure EMImBF₄ exhibits an electrochemical window of 4.4 V,while EMImTFSI exhibits an electrochemical window of 5.0 V.

Electrochemical study of ethanol in perchloric acid showed that the oxidation of ethanol strongly depends on the concentration of ethanol and on the temperature of the solution. The poisoning of the platinum electrode only depends on the concentration of ethanol. At a low concentration of …

"One-Pot" Oligomeric A2 + B3 Approach To Branched Poly(Arylene Ether Sulfone)S: Reactivity Ratio Controlled Polycondensation, Andrea M. Elsen

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The synthesis of fully soluble branched poly(arylene ether)s via an oligomeric A2 + B3 system, in which the A2 oligomers are generated in situ, is presented. This approach takes advantage of the significantly higher reactivity toward nucleophilic aromatic substitution reactions, NAS, of B2, 4-Fluorophenyl sulfone, relative to B3, tris(4-Fluorophenyl) phosphine oxide. The A2 oligomers were synthesized by reaction of Bisphenol-A and B2, in the presence of the B3 unit, at temperatures between 100 and 160 °C, followed by an increase in the reaction temperature to 180 °C at which point the branching unit was incorporated. The presence of branching was …