Open Access. Powered by Scholars. Published by Universities.®

Chemistry Commons™

Open Access. Powered by Scholars. Published by Universities.®

2005

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 541 - 562 of 562

Full-Text Articles in Chemistry

Photochemical Generation Of 2-Methoxy-2methylpropylidene And Its Rearrangement Pathways, Stanislav Presolski Jan 2005

Photochemical Generation Of 2-Methoxy-2methylpropylidene And Its Rearrangement Pathways, Stanislav Presolski

Honors Theses

2-methoxy-2-methylpropylidene was photochemically generated from a non-nitrogenous precursor, 1a,9b-Dihydro-IH-cyclopropa[1]phenanthrene-l-etbane 2-methoxy-2-methyl, available in two steps from phenanthrene. Two competing rearrangement pathways were observed for the p-methoxy carbene, 1,2-methyl shift and C-H insertion, which had varying weights depending on the solvent used. Nevertheless, the C-H insertion was always predominant, contrary to the current understanding of B-substituted carbenes, which apparently needs revision. An attempt was also made to measure by LFP the rate constant of rearrangement and lifetime of the stabilized l-chloro-2-methoxy-2-metbylpropylidene.

Go to article

The Synthesis And Characterization Of Bicyclooxacalixarenes, Kevin J. Selby Jan 2005

The Synthesis And Characterization Of Bicyclooxacalixarenes, Kevin J. Selby

Honors Theses

Bicyclooxacalixarenes were synthesized in high yield via a selective, room temperature Sn Ar reaction of phluoroglucinol with 2,6-dichloropyridines. Functionality on the 2,6-dichloropyridioe was varied by changing the electron-withdrawing groups in the 3 and 5 positions (using chlorine, nitro groups, and cyano groups) and the side-chains in the 4-position (using ethyl, butyl, phenyl and ρ-tolyl groups). The resulting cage-like molecules were studied by X-ray crystallography and tested for metal complexation.

Go to article

The Subsystems Approach To Genome Annotation And Its Use In The Project To Annotate 1000 Genomes, Ross Overbeek, Tadhg Begley, Ralph M. Butler, Jomuna V. Choudhuri, Han-Yu Chuang, Matthew Cohoon, Valérie De Crécy-Lagard, Naryttza Diaz, Terry Disz, Robert Edwards, Michael Fonstein, Ed D. Frank, Svetlana Gerdes, Elizabeth M. Glass, Alexander Goesmann, Andrew Hanson, Dirk Iwata-Reuyl, Roy Jensen, Neema Jamshidi, Lutz Krause, Michael Kubal, Niels Larsen, Burkhard Linke, Alice C. Mchardy, Folker Meyer, Heiko Neuweger, Gary Olsen, Robert Olson, Andrei Osterman, Vasiliy Portnoy, Gordon D. Pusch, Dmitry A. Rodionov, Christian Rückert, Jason Steiner, Rick Stevens, Ines Thiele, Olga Vassieva, Yuzhen Ye, Olga Zagnitko, Veronika Vonstein Jan 2005

The Subsystems Approach To Genome Annotation And Its Use In The Project To Annotate 1000 Genomes, Ross Overbeek, Tadhg Begley, Ralph M. Butler, Jomuna V. Choudhuri, Han-Yu Chuang, Matthew Cohoon, Valérie De Crécy-Lagard, Naryttza Diaz, Terry Disz, Robert Edwards, Michael Fonstein, Ed D. Frank, Svetlana Gerdes, Elizabeth M. Glass, Alexander Goesmann, Andrew Hanson, Dirk Iwata-Reuyl, Roy Jensen, Neema Jamshidi, Lutz Krause, Michael Kubal, Niels Larsen, Burkhard Linke, Alice C. Mchardy, Folker Meyer, Heiko Neuweger, Gary Olsen, Robert Olson, Andrei Osterman, Vasiliy Portnoy, Gordon D. Pusch, Dmitry A. Rodionov, Christian Rückert, Jason Steiner, Rick Stevens, Ines Thiele, Olga Vassieva, Yuzhen Ye, Olga Zagnitko, Veronika Vonstein

Chemistry Faculty Publications and Presentations

The release of the 1000th complete microbial genome will occur in the next two to three years. In anticipation of this milestone, the Fellowship for Interpretation of Genomes (FIG) launched the Project to Annotate 1000 Genomes. The project is built around the principle that the key to improved accuracy in high through put annotation technology is to have experts annotate single subsystems over the complete collection of genomes, rather than having an annotation expert attempt to annotate all of the genes in a single genome. Using the subsystems approach, all of the genes implementing the subsystem are analyzed by …

Go to article

Measurement Of Lipid Peroxidation In Biology Models Using Gas-Chromatography-Aass Spectrometry, Madhavi Lokireddy Jan 2005

Measurement Of Lipid Peroxidation In Biology Models Using Gas-Chromatography-Aass Spectrometry, Madhavi Lokireddy

Master's Theses and Doctoral Dissertations

C2C12 mouse myoblast cells, grown in glass vials, were connected to a cryofocusing unit to trap volatile organic compounds (VOCs). The VOCs were eluted from the trap by capacitive discharge into a gas chromatograph with time-of-flight mass spectral capabilities (GC-TOFMS) and were found to include the lipid peroxidation product hexanal. The pro-oxidant cumene hydroperoxide elevated the levels of these lipid peroxidation products, whereas the anti-oxidant butylated hydroxy toluene (BHT) impaired their production. Derivatization of the aldehyde products of lipid peroxidation in the same myoblast cells with pentafluorobenzyl hydroxylamine hydrochloride (PFB) provided evidence for formation of non-volatile products of lipid peroxidation …

Go to article

Synthetic Development And Application Of Compounds With Biological Relevance, Jeffery Caleb Clark Jan 2005

Synthetic Development And Application Of Compounds With Biological Relevance, Jeffery Caleb Clark

LSU Doctoral Dissertations

Nature has provided a vast number of compounds that have medicinal application. The use of these compounds provided by nature however, is limited by the amount of a specific compound that nature provides. The synthesis of these molecules and their derivatives provides an even greater number of compounds for biological screening. Various pyrroles, the heterocyclic building blocks of porphyrins, can be prepared synthetically over several steps. The implementation of carboranes on pyrrole rings intrinsically provides substrates that can be converted into porphyrins bearing carborane substituents. The condensation of these carboranylpyrroles with carboranylaldehydes provides carboranylporphyrins bearing a higher order of carborane …

Go to article

Synthesis And Characterization Of Membrane Anchored Peptides, Eugenia Christine Tsamis Jan 2005

Synthesis And Characterization Of Membrane Anchored Peptides, Eugenia Christine Tsamis

Honors Program Theses

ln KW ALP23 peptides containing Lysine and Trp, as the Trps were moved further in towards the center of the bilayer, Lys became the dominant anchoring residue (1). The goal of this project was to determine whether Arg exhibits snorkeling behavior similar to Lys, and is able to anchor the peptide in the membrane despite the repositioning of Trp in the RWALP peptides. Several candidate R W ALP23 peptides containing Tryptophan and Arginine with an alternating LeucineAlanine backbone were synthesized successfully. They were then studied by HPLC, CD, and MALDI-TOF Mass Spectrometry to investigate the anchoring roles of Arg and …

Go to article

Isolation, X-Ray Structures, And Electronic Spectra Of Reactive Intermediates In Friedel−Crafts Acylations, M. G. Davlieva, Sergey V. Lindeman, I. S. Neretin, Jay K. Kochi Jan 2005

Isolation, X-Ray Structures, And Electronic Spectra Of Reactive Intermediates In Friedel−Crafts Acylations, M. G. Davlieva, Sergey V. Lindeman, I. S. Neretin, Jay K. Kochi

Chemistry Faculty Research and Publications

Reactive intermediates in the Friedel−Crafts acylation of aromatic donors are scrutinized upon their successful isolation and X-ray crystallography at very low temperatures. Detailed analyses of the X-ray parameters for the [1:1] complexes of different aliphatic and aromatic-acid chlorides with the Lewis acids antimony pentafluoride and pentachloride, gallium trichloride, titanium and zirconium tetrachlorides provide unexpected insight into the activation mechanism for the formation of the critical acylium carbocations. Likewise, the X-ray-structure examinations of aliphatic and aromatic acylium electrophiles also isolated as crystalline salts point to the origins of their electrophilic reactivity. Although the Wheland intermediates (as acylium adducts to arene donors) …

Go to article

The Relationship Between The Solubility Parameter Of Polymers And The Clay-Dispersion In Polymer/Clay Nanocomposites And The Role Of The Surfactant, Bok Nam Jang, Dongyan Wang, Charles A. Wilkie Jan 2005

The Relationship Between The Solubility Parameter Of Polymers And The Clay-Dispersion In Polymer/Clay Nanocomposites And The Role Of The Surfactant, Bok Nam Jang, Dongyan Wang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites were prepared of polymers having different solubility parameters and pristine or organically modified clays, and the dispersion of clay in the polymer was evaluated using X-ray diffraction and transmission electron microscopy. The solubility parameters of both the polymers and surfactants of interest were calculated according to the group contribution method and correlated with the clay morphology. A close relationship between the solubility parameter of the polymer and the clay morphology was observed. The clay has a very polar group, so the higher is the solubility parameter of the polymer, the larger is the d spacing of the clay that …

Go to article

Scope And Mechanistic Study Of The Ruthenium-Catalyzed Ortho-C−H Bond Activation And Cyclization Reactions Of Arylamines With Terminal Alkynes, Chae S. Yi, Young Yun Jan 2005

Scope And Mechanistic Study Of The Ruthenium-Catalyzed Ortho-C−H Bond Activation And Cyclization Reactions Of Arylamines With Terminal Alkynes, Chae S. Yi, Young Yun

Chemistry Faculty Research and Publications

The cationic ruthenium hydride complex [(PCy3)2(CO)(CH3CN)2RuH]+BF4- was found to be a highly effective catalyst for the C−H bond activation reaction of arylamines and terminal alkynes. The regioselective catalytic synthesis of substituted quinoline and quinoxaline derivatives was achieved from the ortho-C−H bond activation reaction of arylamines and terminal alkynes by using the catalyst Ru3(CO)12/HBF4·OEt2. The normal isotope effect (kCH/kCD = 2.5) was observed for the reaction of C6H5NH2 and C …

Go to article

Isolation And X-Ray Structures Of Labile Benzoic- And Acetic-Acidium Carbocations, Sergey V. Lindeman, I. S. Neretin, M. G. Davlieva, Jay K. Kochi Jan 2005

Isolation And X-Ray Structures Of Labile Benzoic- And Acetic-Acidium Carbocations, Sergey V. Lindeman, I. S. Neretin, M. G. Davlieva, Jay K. Kochi

Chemistry Faculty Research and Publications

New carbocationic salts (via O-protonation of substituted benzoic acids) are prepared for the first time by controlled hydration of the corresponding benzoylium salts and isolated in pure crystalline form. Precise X-ray structural analyses reveal the rather unexpected (electronic) structure of the carboxylic-acidium functionality.

Go to article

The Thermal Degradation Of Bisphenol A Polycarbonate In Air, Bok Nam Jang, Charles A. Wilkie Jan 2005

The Thermal Degradation Of Bisphenol A Polycarbonate In Air, Bok Nam Jang, Charles A. Wilkie

Chemistry Faculty Research and Publications

The thermal degradation of polycarbonate in air was studied as a function of mass loss using TGA/FTIR, GC/MS and LC/MS. In the main degradation region, 480–560 °C, the assigned structures of smaller molecules and linear molecules that evolved in air were very similar to those obtained from the degradation in nitrogen; the degradation of polycarbonate follows chain scission of the isopropylidene linkage, in agreement with the bond dissociation energies, and hydrolysis/alcoholysis of carbonate linkage. Compared to the degradation in nitrogen, some differences were observed primarily in the beginning stage of degradation. Oxygen may facilitate branching as well as radical formation …

Go to article

Polyethylene And Polypropylene Nanocomposites Based Upon An Oligomerically-Modified Clay, Jinguo Zhang, David D. Jiang, Charles A. Wilkie Jan 2005

Polyethylene And Polypropylene Nanocomposites Based Upon An Oligomerically-Modified Clay, Jinguo Zhang, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Montmorillonite clay was modified with an oligomeric surfactant, which was then melt blended with polyethylene and polypropylene in a Brabender mixer. The morphology was characterized by X-ray diffraction and transmission electron microscopy, while thermal stability was evaluated from thermogravimetric analysis and the fire properties by cone calorimetry. The nanocomposites are best described as mixed immiscible/intercalated/delaminated systems and the reduction in peak heat release rate is about 40% at 5% inorganic clay loading.

Go to article

The Effects Of Triphenylphosphate And Recorcinolbis(Diphenylphosphate) On The Thermal Degradation Of Polycarbonate In Air, Bok Nam Jang, Charles A. Wilkie Jan 2005

The Effects Of Triphenylphosphate And Recorcinolbis(Diphenylphosphate) On The Thermal Degradation Of Polycarbonate In Air, Bok Nam Jang, Charles A. Wilkie

Chemistry Faculty Research and Publications

The thermal degradation of polycarbonate/triphenylphosphate (PC/TPP) and PC/resocinolbis(diphenylphosphate) (PC/RDP) in air has been studied using TGA/FTIR and GC/MS. In PC/phosphate blends, the phosphate stabilizes the carbonate group of polycarbonate from alcoholysis between the alcohol products of polycarbonate degradation and the carbonate linkage. Thus, the evolution of bisphenol A, which is mainly produced via hydrolysis/alcoholysis of the carbonate linkage, is significantly reduced, while, the evolution of various alkylphenols and diarylcarbonates increases. The bonds that are broken first in the thermal degradation of both the carbonate and isopropylidene linkages of polycarbonate are the weakest bonds in each, when a phosphate is present. …

Go to article

Polystyrene Nanocomposites Based On Carbazole-Containing Surfactants, Grace Chigwada, David D. Jiang, Charles A. Wilkie Jan 2005

Polystyrene Nanocomposites Based On Carbazole-Containing Surfactants, Grace Chigwada, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

New organically-modified clays containing a carbazole unit were prepared and the number of long alkyl chains on the surfactant was varied. The clay was used to prepare polystyrene nanocomposites by both bulk polymerization and melt blending. The dispersion of these clays in the polymer matrix was evaluated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal stability of the clays and the nanocomposites were analyzed by thermogravimetric analysis (TGA) while the fire properties were evaluated by cone calorimetry. If more than two alkyl chains were present, the gallery spacing is apparently overcrowded, leading to poor dispersion. Bulk polymerization …

Go to article

Synthesis Of Cyclopropanes Via Organoiron Methodology: Preparation Of The C9–C16 Alkenylcyclopropane Segment Of Ambruticin, Julie Lukesh, William A. Donaldson Jan 2005

Synthesis Of Cyclopropanes Via Organoiron Methodology: Preparation Of The C9–C16 Alkenylcyclopropane Segment Of Ambruticin, Julie Lukesh, William A. Donaldson

Chemistry Faculty Research and Publications

A synthesis of the C9–C16 segment of ambruticin is described which relies on organoiron methodology to establish the 1,2,3-trisubstituted cyclopropane ring.

Go to article

Methyl Methacrylate Oligomerically-Modified Clay And Its Poly (Methyl Methacrylate) Nanocomposites, Xiaoxia Zheng, David D. Jiang, Charles A. Wilkie Jan 2005

Methyl Methacrylate Oligomerically-Modified Clay And Its Poly (Methyl Methacrylate) Nanocomposites, Xiaoxia Zheng, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

A methyl methacrylate oligomerically-modified clay was used to prepare poly(methyl methacrylate) clay nanocomposites by melt blending and the effect of the clay loading level on the modified clay and corresponding nanocomposite was studied. These nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry. The results show a mixed intercalated/delaminated morphology with good nanodispersion. The compatibility between the methylacrylate-subsituted clay and poly(methyl methacrylate) (PMMA) are greatly improved compared to other oligomerically-modified clays.

Go to article

Characterization Of Aged Polymer Modified Asphalt Cements For Recycling Purposes, Codrin Daranga Jan 2005

Characterization Of Aged Polymer Modified Asphalt Cements For Recycling Purposes, Codrin Daranga

LSU Doctoral Dissertations

Since polymer modified asphalt cement (PMAC) has been employed for a decade, the lifetime and wear on some of these pavements is reaching a stage where resurfacing is necessary. This research focuses on the characterization of aged polymer modified asphalt cements (PMAC) to evaluate their potential for recycling. A styrene-butadiene-styrene tri-block (SBS) polymer modified asphalt cement was selected and characterized using standard asphalt binder qualification techniques, i.e., the Superpave PG protocol. We developed a procedure to characterize the relative concentration of polymer in asphalt cements by gel permeation chromatography (GPC). Infrared spectrographic, thermogravimetric and rheological techniques were used to identify …

Go to article

Enantioselective Syntheses And Chemical Investigations Of Plant-Derived Bioactive Volatile Compounds, Anne Marie Sauer Jan 2005

Enantioselective Syntheses And Chemical Investigations Of Plant-Derived Bioactive Volatile Compounds, Anne Marie Sauer

LSU Doctoral Dissertations

Research, inspired by nature, provides ample opportunity for discovery, ingenuity, and creative endeavor. For these reasons, the work and accomplishments presented herein focus on the total syntheses and related investigations of a variety of natural product derivatives, specifically (+)-nootkatone and jasmone. While the former consists of several independent projects: (a) an enantioselective synthetic route to (+)-nootkatone and derivatives, (b) examination of the valencane ring system, (c) determination of the absolute configuration of (+)-nootkatone, and (d) rearrangements of various sesquiterpenoid derivatives; the latter focuses on the construction ofƒndelta, epsilon-unsaturated carbonyl compounds, hetero Pauson-Khand substrates, via [3,3]-sigmatropic rearrangements.

Go to article

Infrared And X-Ray Spectroscopic Studies Of The Copper(Ii) Oxide Mediated Reactions Of Chlorinated Aromatic Precursors To Pcdd/F, Steven L. Alderman Jan 2005

Infrared And X-Ray Spectroscopic Studies Of The Copper(Ii) Oxide Mediated Reactions Of Chlorinated Aromatic Precursors To Pcdd/F, Steven L. Alderman

LSU Doctoral Dissertations

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) are toxic compounds produced in combustion systems such as incinerators, and their emissions are an important environmental issue. Chlorinated phenols and benzenes form PCDD/F through heterogeneous reactions following adsorption onto fly-ash surfaces. Current research implicates transition metals in promoting formation of phenoxyl radicals that react to form PCDD/F, although this has not been studied extensively. This objective of this work is to better understand PCDD/F formation from chlorinated aromatic precursors. Using 2 chlorophenol as a model PCDD/F precursor and silica as a fly-ash surrogate, time-dependent chemisorption of 2 chlorophenol onto silica was studied in situ …

Go to article

Separation And In Situ Catalytic Testing Of A Dirhodium Tetraphosphine Catalyst, Bobby Lloyd Barker Jan 2005

Separation And In Situ Catalytic Testing Of A Dirhodium Tetraphosphine Catalyst, Bobby Lloyd Barker

LSU Doctoral Dissertations

Attempts to study the asymmetric hydroformylation abilities of [rac-Rh2(nbd)2(et,ph-P4)](BF4)2 were made through the separation of the enantiomers of et,ph-P4 using a chiral HPLC column. Efforts were also made to optimize the NiCl2 separation chemistry for the methyl analogue of et,ph-P4 for use in asymmetric hydroformylation. A study of hydroformylation of olefins using [rac-Rh2(nbd)2(et,ph-P4)](BF4)2 in ionic liquids was also performed, leading directly to the important (and unexpected) effect of increased hydrogen pressure on [rac-Rh2(nbd)2(et,ph-P4)](BF4)2 in the acetone/water system to …

Go to article

Synthesis And Characterization Of Rhodium And Iridium Complexes With The Bis(Dimethylsilylcyclopentadienyl) Ligand, Gordon J. Hunter Jan 2005

Synthesis And Characterization Of Rhodium And Iridium Complexes With The Bis(Dimethylsilylcyclopentadienyl) Ligand, Gordon J. Hunter

Dissertations and Theses @ UNI

The synthesis of transition-metal complexes ( n5 -C5H3SiMe2)2[Rh(CO)2]2 and ( n5- -C5H3SiMe2)2[Rh(CO)2]2, both featuring the bis( dimethylsilylcyclopentadienyl) ligand, is reported. Preparation of the rhodium complex yielded a cis:trans ratio of 1 :2, while the iridium analogue generated a 2: 1 ratio. Thermal reaction of cis-( n5- - C5H3SiMe2)2[Rh(CO)2]2 yields cis-( n5 -C5H3SiMe2)2Rh2(CO)3, which features an asymmetrically bridging carbonyl ligand. Reaction of I2with cis-( n5- - C5H3SiMe2)2[Ir(CO)2]2 yields cis-( n5 -C5H3SiMe2)2[Ir(CO)I2]2 Synthesis of ( n5- - C5H3SiMe2)2[Ir(cyclooctadiene)h in a cis:trans ratio of 1 :2.5 is also reported.

Go to article

Melting And Solidification Study Of Indium And Bismuth Nanocrystals Using Reflection High-Energy Electron Diffraction, Mohamed K. Zayed Jan 2005

Melting And Solidification Study Of Indium And Bismuth Nanocrystals Using Reflection High-Energy Electron Diffraction, Mohamed K. Zayed

Electrical & Computer Engineering Theses & Dissertations

As technology begins to utilize nanocrystals for many chemical, biological, medical, electrical, and optoelectrical applications, there is a growing need for an understanding of their fundamental properties. The study of melting and solidification of nanocrystals is of interest to fundamental understanding of the effect of reduced size and crystal shape on the solid-liquid phase transition. Melting and solidification of as-deposited and recrystallized indium and bismuth nanocrystals were studied using reflection high-energy electron diffraction (RHEED). The nanocrystals were thermally deposited on highly oriented 002-graphite substrate at different deposition temperatures. The growth dynamics of the nanocrystals was studied using in situ RHEED …

Go to article

First Prev