Chemistry Commons^™

Preparation Of Methyl 5-Chloro-6-Fluoronicotinate By Fluoride-Chloride Exchange, Frank L. Setliff, Leslie B. Coop

Journal of the Arkansas Academy of Science

No abstract provided.

A Kinetic Study Of The Photolysis Of Ethylferrocene In Chloroform, Son L. Phan, Patrick E. Hoggard

Chemistry and Biochemistry

The photooxidation of ethylferrocene to ethylferricinium ion and tetrachloroferrate in CHCl3 under 254 nm irradiation proceeds through light absorption by both ethylferrocene and chloroform. The products remain in solution at concentrations below 10-3 M. The fraction occurring through a solvent-initiated pathway increases during the course of the reaction. A secondary thermal reaction is responsible for generating tetrachloroferrate from ethylferricinium ion. The rate of the reaction increases during the early stages, and the data throughout the course of the reaction are consistent with the rate law ( afs + bfR)/ (1 + c[R]/[P]-d[R]/[Cl ]), where [R] and [P] are the concentrations …

Visual Form Of Alzheimer's Disease And Its Response To Anticholinesterase Therapy, Stacey Warren, Daniel B. Hier, Dan Pavel

Chemistry Faculty Research & Creative Works

In a 60-Year-Old Woman with the Visual Variant of Alzheimer's Disease, Single Photon Emission Computed Tomography Abnormalities Were Most Marked in the Parieto-Occipital Regions of the Brain. after Treatment with Donepezil, Improvement is Noted on Neuropsychological Testing and on Brain SPECT, Including Increased Perfusion (Metabolism) in the Occipital Lobes.

Pressure Induced Reversal Of The Volume Expansion Caused By Interstitial Nitrogen In Nd2fe17n3, G. K. Marasinghe, William Joseph James, P. C. Ezekwenna, H. Luo, W. B. Yelon, Y. Zhao, R. B. Von Dreele, M. Ellouze, Ph L'Héritier

Chemistry Faculty Research & Creative Works

Crystallographic properties of Nd2Fe17N3 have been investigated using powder neutron diffraction techniques at pressures up to 7.3 GPa. With increasing pressure, the unit cell volume of Nd 2Fe17N3 decreases almost linearly at a rate of 6.1 Å3/GPa without undergoing a phase transformation or expelling the interstitial nitrogen atoms. The observed rate of contraction corresponds to a bulk modulus of 1.4x1011 N/m2 for Nd2Fe17N3. The unit cell volume of Nd 2Fe17N3 at 7.3 GPa is approximately equal to that of Nd2Fe17 at atmospheric pressure. Even though the unit cell of Nd2Fe17 expands anisotropically due to nitrogenation, contraction of the Nd2Fe17N3 unit …

The Evolution Of Chiral Stationary Phases For Liquid Chromatography, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

The development of effective chiral stationary phases (CSPs) and separation strategies for the liquid chromatographic (LC) resolution of enantiomers has been beneficial to many scientific disciplines. Over the last decade the number and type of CSPs has expanded tremendously. Not only have new classes of chiral selectors been introduced, but also many of the first CSPs have been changed and/or improved. The second or third generation of a CSP often can be different from the original. This can be confusing and intimidating to someone just entering the area of LC enantiomeric separations. Fortunately, all CSPs can be categorized in one …

Deuterium Nmr Of Adsorbed Poly(Methyl Acrylate)-D₃, Frank D. Blum, Wuu-Yung Lin

Chemistry Faculty Research & Creative Works

The dynamics of polymers at interfaces are important in a variety of applications, especially where those applications depend on the mechanical or surface properties. Unfortunately, the surface properties of interfacial species like polymers used in composites are not easily measured macroscopically. Microscopic techniques, especially spectroscopic ones, have been successful. In our laboratory we have been successful in applying NMPR to determine the behavior of absorbed polymers. NMR has several advantages for this kind of study, the principal ones being that it can be used on opaque materials, different nuclei can be used as probes, and interfacial material can sometimes be …

Structural And Magnetic Properties Of Rsr₂Fe₃O₉ (R=La, Y, Pr, And Gd), I. Felner, I. Nowik, A. Mehta, Rajvir Singh, William B. Yelon, V. P. S. Awana, S. X. Dou, Satish K. Malik, A. V. Narlikar

Chemistry Faculty Research & Creative Works

No abstract provided.

Methods Of Preparing Three-Dimensional, Macroscopic Assemblages Of Carbon Fibrils And The Products Obtained Thereby, Hyperion Catalysis International, Inc., Howard Tennent, Robert W. Hausslein, Nicholas Leventis, David Moy

Chemistry Faculty Research & Creative Works

A method of making randomly oriented carbons fibrils having a cylindrical constant diameter with c-axes perpendicular to their cylindrical axis, which are free of pyrolytically deposited carbon, with a diameter of between 3.5 and 70 nanometers, by dispersing carbon fibrils in a medium and separating them from the medium, by filtration or evaporation to form a porous mat or sheet.

Ab Initio And Dft Investigations Of Lithium/Hydrogen Bonded Complexes Of Trimethylamine, Dimethyl Ether And Dimethyl Sulfide, Salai Cheettu Ammal, P. Venuvanalingam

Faculty Publications

Ab initio and DFT computations have been carried out on LiF and HF complexes of a set of n-donors viz. trimethylamine, dimethyl ether and dimethyl sulfide with a 6-31++G(d,p) basis set. The effect of correlation has been included with MP2, MP4 and DFT calculations. NBO analyses of the wavefunctions have been performed to examine the intermolecular interaction at the orbital level. Calculations reveal that these donors form strong n→σ* complexes and computed binding energies of the (CH₃)₂O···HF complex agree very well with the experimental binding energies from IR spectroscopy. LiF forms stronger complexes than HF, …

Disproportionation And Structural Changes Of Tetraarylethylene Donors Upon Successive Oxidation To Cation Radicals And To Dications, Rajendra Rathore, Sergey V. Lindeman, A. S. Kumar, Jay K. Kochi

Chemistry Faculty Research and Publications

The stepwise (one-electron) chemical oxidation of the tetraphenylethylene donor and its substituted analogues (D) can be carried out by electron exchange with aromatic cations or antimony(V) oxidants to selectively afford the cation radical (D^+•) initially and then the dication (D²⁺). The ready interchange of the latter establishes the facile disproportionation (i.e., 2D^+• ⇌ D²⁺ + D) that was originally examined by only transient electrochemical techniques. The successful isolations of the crystalline salts of the tetraanisylethylene cation radical (1^+•) as well as the …

Influence Of Growth Conditions, Inversion Domains, And Atomic Hydrogen On Growth Of (0001_) Gan By Molecular Beam Epitaxy, Michelle Richards-Babb

Faculty & Staff Scholarship

Growth of GaN by rf-plasma molecular beam epitaxy leads to different surface morphologiesfor nitrogen-stable growth versus gallium-stable growth. Nitrogen-stable growth produces a granular surface morphology with many samples having a significant density of pyramidal hillocks. In contrast, gallium-stable growth results in a flat surface morphology. The hillocks were directly linked to the presence of inversion domains which originated in the nucleationlayer. Nitrogen-stable growth and growth under atomic hydrogen enhanced the growth rate of inversion domains with respect to the surrounding matrix, while growth under Ga-stable conditions resulted in a more nearly equal growth rate. Evidence is presented suggesting that hydrogen …

Novel Synthetic Route To 5-Substituted Indoles, Helen Y. Chen

Master's Theses

No abstract provided.

Preparation And Structures Of Crystalline Aromatic Cation-Radical Salts. Triethyloxonium Hexachloroantimonate As A Novel (One-Electron) Oxidant, Rajendra Rathore, A. S. Kumar, Sergey V. Lindeman, Jay K. Kochi

Chemistry Faculty Research and Publications

Triethyloxonium hexachloroantimonate [Et₃O⁺SbCl₆^-] is a selective oxidant of aromatic donors (ArH), and it allows the facile preparation and isolation of crystalline paramagnetic salts [ArH^+•, SbCl₆^-] for the X-ray structure determination of various aromatic cation radicals. The mechanistic relationship between the Meerwein salt [Et₃O⁺SbCl₆^-] and the pure Lewis acid oxidant SbCl₅ is based on a prior ethyl transfer from oxygen to chlorine within the ion pair.

Photoinduced Coupling Of Acetylenes And Quinone In The Solid State As Preorganized Donor−Acceptor Pairs, E. Bosch, S. M. Hubig, Sergey V. Lindeman, Jay K. Kochi

Chemistry Faculty Research and Publications

Crystalline electron donor−acceptor (EDA) complexes of various diarylacetylenes (DA) and dichlorobenzoquinone (DB) are isolated and structurally characterized by X-ray crystallography. Deliberate excitation of either the DB acceptor at λ_DB = 355 nm or the 1:2 [DA, 2DB] complex at λ_CT = 532 nm in the solid state leads to [2 + 2] cycloaddition and identical (isomeric) mixtures of the quinone methide products. Time-resolved (ps) diffuse reflectance spectroscopy identifies the ion-radical pair [DA^•+, DB^•-] as the reactive intermediate derived by photoinduced electron transfer in both photochemical …

Synthesis And Characterization Of A Trypsin Inhibitor, Eric L. Schneider

Honors Theses, 1963-2015

Inhibitors of biological enzymes are frequently produced by mimicking the molecular structure of the enzyme's natural substrate. Because of the extensive studies that have already been performed on the trypsin enzyme, its natural substrates and its mode of interaction with them are well understood. By finding an easily synthesized molecule to inhibit the trypsin enzyme, college level laboratory experiments could be designed and integrated into organic chemistry and biochemistry courses. In this project, a possible trypsin inhibitor molecule, 4-fluorobenzylaimine, was chosen based on its similarity to the natural trypsin substrates and because it has been predicted through computational studies to …

The CuA Center Of A Soluble Domain From Thermus Cytochrome Ba3. An Nmr Investigation Of The Paramagnetic Protein. A Proton Nmr Study Of The Paramagnetic Active Site Of The CuA Variant Of Amicyanin, Richard C. Holz

Chemistry Faculty Research and Publications

No abstract provided.

Kinetic Studies Of The Thermal Decomposition Of Di- And Tri-Organotin Derivatives Of 1-Nitroso-2-Naphthol, Saqib Ali, Moazzam H. Bhatti, Sohail Mahmood, Muhammad Mazhar, M. Saleem Khalid, Nazar Hussain

Turkish Journal of Chemistry

The di- and tri-organotin complexes of general formula R$_2$SnL$_2$ and R$_3$SnL where R = C$_4$H$_9$, C$_6$H$_5$, C$_6$H$_5$CH$_2$, C$_6$H$_{11}$ and L=1-nitroso-2-naphthol, were subjected to thermal decomposition by means of thermogravimetry (TG). The decomposition occurred in steps and the kinetics of every set of reactions were determined using the method described by Coats and Redfern. These results were analysed to establish the decomposition kinetics and hence to calculate activation energies. The activation energies were also determined by applying the method described by Horowitz, which yielded comparable results.

Patterns Of Organochlorine Pesticide Contamination In Neotropical Migrant Passerines In Relation To Wintering Range And Wintering Habitat, Jeffrey A. Klemens '98

Honors Projects

Seventy-two Neotropical migrant passerines were analyzed for the presence of 17 organochlorine pesticide residues (aldrin; alpha-BHC; beta-BHC; gamma-BHC; delta-BHC; p,p'-DDD; p,p'-DDE; p,p'-DDT; dieldrin; endosulfan I; endosulfan II; endosulfan sulfate; endrin; endrin aldehyde; heptachlor- heptachlor epoxide; methoxychlor) using standard method of gas chromatography applied to bird tissues. Individuals were colIected along the Mississippi River during May 1996 and represent 11 species (Catharus ustulatus; Geothlypis trichas; Protonotaria citrea; Mniotilta varia; Contopus virens; Dendroica petechia; Ernpidonax minimus; Passerina cyanea; Myiarchus crinitus; Vireo gilvus). The contaminants most frequently detected were p,p'-DDE, dieldrin, and heptachlor epoxide. No significant difference was found between male and female …

The Total Synthesis Of A Conformationally Constrained Organophosphorus Analog Of Acetycholine, Justin Mergott '98

Honors Projects

We propose the total synthesis of a conformationally constrained organophosphorus analog of acetylcholine (5, Scheme 5). This compound will contain two crural centers, one being the phosphorus atom and the other being the pyrrolidine ring carbon beta to the phosphorus atom. The chiral beta carbon is conformationally constrained because it is part of the pyrrolidine ring. Studies with such a compound should allow us to make substantial progress towards the clarification of the stereospecificity of AChE inhibition by OP compounds and eventually help us understand more about the structure of the AChE active site. The synthesis begins with Cbz-L-proline methyl …

Remote Sensing Of Commercial Aircraft Emissions, Peter J. Popp, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

A Neutron Diffraction Structural Study Of R₂Fe₁₇₋ₓalx(C) (R=Tb,Ho) Alloys, William B. Yelon, H. Luo, Mingxing Chen, W. C. Chang, S. H. Tsai

Physics Faculty Research & Creative Works

No abstract provided.

Neutron Diffraction And Frequency Dependence Of The A.C. Susceptibility Of The System Zncr₂Xal₂-₂Xs₄, M. Hamedoun, A. Hourmatallah, N. Benzakour, K. Mediouri, J. Ilali, William B. Yelon, H. Luo

Physics Faculty Research & Creative Works

No abstract provided.

Magnetic And Thermal Properties Of Pr In La₁₋ₓprxbacacu₃O₇ System With 0.0, Rajvir Singh, S. Uma, E. Gmelin, William B. Yelon, V. P. S. Awana, S. X. Dou, A. V. Narlikar, Satish K. Malik

Physics Faculty Research & Creative Works

No abstract provided.

Pressure Induced Reversal Of The Volume Expansion Caused By Interstitial Nitrogen In Nd₂Fe₁₇N₃, R. Luo, William B. Yelon, Yusheng S.. Zhao, M. Ellouze, Ph. I'Héritier, G. K. Marasinghe, Peter C. Ezekwenna, R. B. Von Dreele, William Joseph James

Physics Faculty Research & Creative Works

No abstract provided.

Metathesis-Based Synthesis Of Jasmonate And Homojasmonate Lactones, Candidates For Extracellular Quorum Sensing Molecules In Candida Albicans, Su C. Cho, Patrick Dussault, Amber D. Lisec, Ellen C. Jensen, Kenneth W. Nickerson

Department of Chemistry: Faculty Publications

Ring-closing metathesis of jasmonate esters is shown to provide a rapid entry to jasmonate lactones. The lactones were investigated as possible quorum sensing molecules for the fungi Candida albicans. Assays demonstrated no effect on fungal morphology at concentrations up to 96 mM.

Substituted Polythiophenes From Highly Reactive Zinc Reagents, Reuben D. Rieke

Department of Chemistry: Faculty Publications

A novel Zerovalent zinc species and an organozinc reagent are disclosed. The zerovalent zinc species is directly pro duced by reaction of a reducing agent on a zinc salt, preferably Zn(CN)₂. The organozinc reagent results from the reaction of the zerovalent zinc species and an organic compound having one or more stable anionic leaving groups. These organozinc reagents include a wide spectrum of functional groups in the organic radical, and are useful in a variety of reactions schemes.

Cross-Coupling Of Organic Compounds Using Cuprous Odide, Reuben D. Rieke

Department of Chemistry: Faculty Publications

Cross-coupling or addition reactions of organic compounds, including acid halides, allylic halides, and C.B-unsaturated carbonyl containing compounds, with organozinc com pounds may be readily and Safely carried out in the presence of cuprous iodide. The use of this catalyst in the coupling reaction provides for the preparation of commercially useful products in the pharmaceutical, agrochemical and other industries.

Kurt Mislow Honorary Issue Of Chirality, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

No abstract provided.

Paramagnetic Nuclear Magnetic Resonance (Nmr) Studies On The Calcium Binding Site Of [Alpha]-Lactalbumin, Thomas Kurt Ritter

Dissertations and Theses

Paramagnetic NMR has drawn interest as a technique for extending the range of systems that can be investigated. The purpose of this study was to determine whether a combination of paramagnetic two-dimensional and relaxation techniques allows for assigning resonances corresponding to residues forming the metal binding site of proteins in which the metal is coordinated exclusively by amino acid side chains and which have been previously inaccessible to assignment.

α-Lactalbumin (LA) is a calcium binding protein with relatively broad NMR signals; this broadness has prevented complete assignment. LA has been the subject of many studies, because it can form a …