Chemistry Commons^™

The Reactivity Of Boron And Aluminum Compounds With Silica Gel Surfaces, Jeannine M. Christensen

Masters Theses

The unmodified silica gel surface contains isolated silanols, vicinal silanols, and siloxane species. Silica gels can be thermally and/or chemically treated to obtain a desired surface. Hexamethyldisilazane (HMDS) was used to chemically modify the silica gel to obtain a surface that contains vicinal silanol groups and siloxane species. The silica gel was thermally treated at 600°C to create a surface that contains isolated silanols and siloxane species. Four types of silica gels (unmodified, 600°C, HMDS and 600°C/HMDS) were reacted with three boron compounds. The boron compounds used were boron trichloride (BCl₃), triethyl borane (B(CH₂CH₃) …

Linkage Isomers Of Tungsten Carbonyl Complexes Of Ph₂Pch₂Pphch₂Pph₂, Chaminda P. Gamage

Masters Theses

The linkage isomers (CO)₅W[η¹-PPh₂CH₂PPhCH₂PPh₂], 1, and (CO)₅ W[η¹-PPh(CH₂PPh₂)₂], 2, have been synthesized from the reaction of (OC)₅W(NH₂Ph) and Ph₂PCH₂PPhCH₂PPh₂. In addition, linkage isomers (CO)₅W[μ-PPh₂CH₂PPhCH₂PPh₂]-W(CO)₅, 3, and (CO)₅W{μ-PPh₂CH₂PPh[W(CO)₅] CH₂PPh₂}, 4, have been prepared. Attempts to obtain (OC)₅WPPh₂CH …

A Ring-Closing Strategy For The Synthesis Of Β,Γ-Unsaturated Δ-Lactones, Erbing Hua

Masters Theses

Spiro β,γ-unsaturated δ-lactones and fused β,γ-unsaturated δ-lactones are integral to a large number of naturally occurring compounds exhibiting a diverse range of biological activity. A new synthetic route to β,γ-unsaturated δ-lactones, consisting of a three-step sequence, has been investigated for the synthesis of these kinds of pharmacological intermediates. Ring closure of a β-hydroxy acid by dehydration, providing a 4-vinyl substituted β-lactone, and its ring expansion/rearrangement are the two key steps in this protocol. The results have proved that this new method is efficient and quite expeditious. One spiro and four fused β,γ-unsaturated δ-lactones were synthesized through this protocol albeit in …

The Synthesis Of 2-Indenylphenols: Potential Ligands For Transition Metals, Yoon Jae Kim

Masters Theses

The syntheses of 2-(2-indenyl)-phenol and 2-(1-indenyl)-phenol via a three-step sequence have been developed. In the first steps of the sequence, a Grignard reagent formed from 2-iodoanisole or 2-bromoanisole reacted with 1-indanone or 2-indanone in yields that ranged from 11.3% to 67.2%. The second step consisted of acid-catalyzed dehydration of the alcohol formed in step 1 to make a 2-inenyl anisole; yields in the second step were 45.2% to nearly quantitative. Finally, demethylation of the 2-indenyl anisole was achieved with AlBr₃ in ethanethiol in yields ranging from 52.9% to 0 %. Each product was characterized by ¹H and ^{13 …}

Allosteric Tuning Of Ruthenium 2,2’-Bipyridyl Luminescent Sensor Systems, Daqing Gan

Masters Theses

A series of new ruthenium bipyridyl crown supramolecular sensor systems containing two binding sites were synthesized. The crystal structure and photophysical properties of the developed sensor systems were thoroughly studied using x-ray, nuclear magnetic resonance and photoscopy methods. It turned out that the chelation of transition metal on the remote sites of the bipyridyl crown ligands greatly reduced the reactivity of the crown cavity. It is believed that the chelation of transition metal on the nitrogen atoms forces the bipyridyl function towards coplanarity and restricts the conformational freedom of the crown ring. The conformational rigidity in turn influences the binding …

Photophysical Study Of Linked 1,4,7-Triazacyclonane Cr (Iii) Complexes, Weizhen Tu

Masters Theses

A series of mono and bimetallic Cr(III) complexes based on the 1,4,7- triazacyclonoane(TACN) were prepared. Complexes of the Cr(TACN)X₃ , and Cr₂(DTNE)X₆ demonstrated marked difference of photophysical properties on the nature of X. In cases where X is more easily oxidized, enhanced extinction coefficient in the ⁴A₂ ➔ ²T, absorption and larger quantum yield of emission at 77K were observed in the dimer complexes. Shorter lifetime and enhanced decay rate were also found in the dimer complexes suggests that there might exists weak coupling behavior between the two Cr(III) metal cents in the …

Reaction Of Caffeic Acid With Amino Acids, Yonggang Wang

Masters Theses

The reaction of caffeic acid with tryptophan was studied as a model for the reaction of caffeic acid with amino acids in the aquatic environment. Although the autoxidation reaction of caffeic acid in aqueous solution with subsequent dimerization had been previously studied, it was examined as well for comparison purposes. The present studies demonstrate that oxidized caffeic acid would react with tryptophan. The reaction, like the dimerization reaction, was catalyzed by the presence of iron(III) ions at low pH ( <4) and by hydroxide ions at high pH (10). The reaction of caffeic acid with itself yielded six products, four of which were identified by mass spectroscopy as dimers, with the other two being trimers. The reaction of caffeic acid with tryptophan yielded three product peaks. Two of the product peaks had similar retention times to the dimers from the self-reaction of caffeic acid; the third was a new product resulting from the reaction of caffeic acid with the tryptophan.

A mechanism for the reaction of caffeic acid with tryptophan has been proposed. This mechanism was based on the analysis …

Photodegradation Of Pcbs In Natural Waters, Adriana R. Nicolaescu

Masters Theses

PCBs are widely distributed in the environment and they are biologically refractory and toxic compounds. There is great interest in understanding their fate in the environment, and also for finding safe and effective degradation methods.

This study is concerned with the photodegradation of four PCB congeners: PCB 5, PCB 18, PCB 77, PCB 128 in natural waters. Natural waters contain humic substances which can greatly influence the environmental fate of the PCBs. The different degradation of the four congeners was studied in standardized systems and in humic acid or nitrate solutions, under environmental conditions. DMDE and Methoxyclor (whose environmental half-lifetimes …

Validation Of The Thermochemical Cycle Used In Computing Absolute Gas Phase Acidities And A Molecular-Orbital Study Of Protonated Ammonia-Water Cluster Ions, Jeremiah Aeschleman

Masters Theses

This work is comprised of two separate computational projects, an evaluation of the validity of an assumption made when computing absolute gas phase acidities with a thermochemical cycle and a molecular-orbital study of protonated ammonia-water clusters ions.

Relative gas phase acidities are measured experimentally and then adjusted using Hess' law to align them with an absolute scale. In the Hess' law calculation it is assumed that the electron affinity of A• and the ionization energy of H• are independent of temperature. To test this assumption, absolute enthalpies were computed for the anion (A^-) and the radical (A•) at …

A Time Resolved Laser Spectroscopy Study Of Resonance Energy Transfer Between Tb(Iii) And An Organic Dye: 6-Hydroxy-5-[(2-Methoxy-5-Methyl-4-Sulfophenyl)Azo]-2-Naphthalenesulfonic Acid Disodium Salt, Ronald Wesley Tennis

Masters Theses

Intermolecular energy transfer is a process of crucial importance to photochemistry and photophysics. Complexed lanthanide ions are well suited as energy transfer donors because they display dependable absorption and luminescence qualities with narrow rare-earthion emission in addition to relatively long excited-state lifetimes.

This project used a pulsed nitrogen laser and high speed digital techniques to study energy transfer dynamics between excited state Tb(acac)₃ and an ionic organic dye called Red 40. Luminescence decay profiles of excited terbium atoms in the presence of the quencher were measured in both high and low viscosity solvents. The effects of solvent viscosity and …

Equilibrium And Kinetic Studies Of Isomerization Of (Co)5w[Η1-Pph2ch2p(P-Tol)2] And (Co)5w[Η1-P(P-Tol)2ch2pph2], Deliang Chen

Masters Theses

Unsymmetrical diphosphine tungsten complexes, (CO)₅W[η¹-PPh₂CH₂P(p-tol)₂] and (CO)₅W[η¹-P(p-tol)₂CH₂PPh₂], were prepared from (CO)₅W(NH₂Ph) and Ph₂PCH₂P(p-tol)₂. Two approaches were successfully used to synthesize Ph₂PCH₂P(p-tol)₂. The first utilized PPh₂CH₂Cl, prepared from PPh₂H, CH₂Cl₂, and KOH under phase transfer conditions, from which Ph₂PCH₂P(p-tol)₂ was …

Investigations Into The Synthesis And Transformations Of An Epoxy Β-Lactone, John Farrell

Masters Theses

In connection with the continuing interests in the stereoselective rearrangements of β-lactones, an investigation of the synthesis and transformations of the epoxy β-lactone 4-(1,2-epoxypentyl)-3-trimethylsilyloxetan-2-one was undertaken. Two synthetic strategies to the desired epoxy β-lactone were studied. The first route was a two-step reaction sequence involving the aldol reaction of trimethylsilylacetic acid with (2R,3S)-epoxyhexanal, followed by lactonization of the resulting β-hydroxy acid with benzenesulfonyl chloride. Complications in preparing the requisite β-hydroxy acids under typical aldol reaction conditions rendered this route unworkable. The complexity and intractability of the aldol reaction mixtures was attributed to the multiple possibilities of …

Degradation Of Trazine Compounds Via Metallic Iron Under Acidic Conditions, Tracy Dombek

Masters Theses

The degradation of dissolved dimethoxyatrazine (2-chloro-4,6-dimethoxy-1,3,5-triazine), terbutylazine (2-chloro-4-ethylamino-6-terbutylamino-1,3 ,5-triazine) and deisopropylatrazine (2-amino-4-chloro-6-ethylamino-1,3,5-triazine) via metallic iron was studied as a function of solution pH. Generally, degradation was more rapid the lower the solution pH and higher the compound pKa. For dimethoxyatrazine k_SA (k_SA= k' (min^-1)* V (L) / M (g) I SA(m²/g)) was found to be 1.33 (± 0.07) E-4 min^-1 m^-2 L at pH 2, 6.1 (± 0.6) E-5 min^-1 m^-2 L at pH 3 and 4.4 (± 0.6) E-5 min^-1 m^-2 L at pH 4. For …

Alkyl Nitrates During The Prophet ’98 Summer Intensive, Kristi A. Ostling

Masters Theses

As part of the PROPHET intensive held at the University of Michigan Biological Station in northern Michigan, a gas chromatography system for making fast-turnaround measurements of C1 to C5 alkyl nitrates was developed and deployed from July 19 to August 21, 1998. Every 30 minutes, samples were automatically acquired on a small Tenax trap made from silicosteel column and injected on a GC column by thermal desorption prior to ECD detection. Tests performed to measure breakthrough and on-trap destruction indicated no breakthrough for C3, C4, and C5 nitrates and excellent stability for these compounds on the trap. Chromatographic resolution of …

Spectroscopic And Kinetic Investigation Of Carbocation Reactivity In Supercritical Carbon Dioxide, Hongshu Jin

Masters Theses

Recent interest in the use of supercritical CO₂ as an environmentally benign reaction medium has included the development of solvent systems that may support polar and ionic chemistry. Carbocations are key intermediate in a variety of synthetically important reactions and characterization of their reactivity is the focus of this work. UV-visible absorption, and steady-state and time-resolved fluorescence spectroscopy has been used to identify and monitor the reaction kinetics of 9- phenylxanthenium carbocation. The arylcarbocation is conveniently generated from 9- phenylxanthen-9-ol in supercritical CO₂ under mildly acidic conditions. Under these conditions 9-phenylxanthenium ion is extremely stable and persists for …

Gas Sparging And Humic Acid Sorption/Desorption, Masaki Sakakibara

Masters Theses

Partition coefficients (K_DOC) for sorption of PAHs and chlorinated benzenes to dissolved humic acids (HA) were measured using gas-sparging methodology. The resulting K_DOC values were significantly lower than the K_OW-based K_DOC values, which generally appear to provide reliable estimates for K_DOC values. The K_DOC values measured by gas sparging were also strongly influenced by the concentration of HA in solution, as measured by dissolved organic carbon content (DOC). Increasing DOC concentration consistently resulted in decreased K_DOC values for all compounds investigated. Previous studies have claimed that K_DOC values measured using …

Investigating The Allosteric Behavior Of Malate Dehydrogenase From Escherichia Coli, Eman M. Ghanem

Masters Theses

Regulatory mechanisms of malate dehydrogenase from E.coli (eMDH) involving NADH as an allosteric effector were investigated. The reaction was studied in both directions: malate oxidation and oxaloacetate reduction. When malate was the variable substrate, a plot of rate against substrate concentration was sigmoidal in the presence of 0.065 mM NADH, which indicates the presence of an allosteric site for NADH on the enzyme. Binding of NADH at the allosteric site causes conformational changes in the active site and, thereby, changes the catalytic activity of the enzyme. An increase in K_m value, from 1.3 to 3.9 mM malate was observed, …

Optimization Of The Reaction Of Hexamethyldisilazane On A Fumed Silica Surface, Frederick R. Jones

Masters Theses

Hexamethyldisilazane (HMDS) is commonly used to transfer trimethylsilyl (TMS) groups to silica surfaces. While studies have been done examining individual factors that influence the reaction, no investigations have reported how these factors affect each other. The factors examined in this study include temperature, presence of catalyst (butylamine), pretreatment, time, concentration, solvent, and presence of water in the solvent. The purpose of this study is to examine potential factors and two-way interactions to determine which significantly affect the yield and produce an optimum set of conditions.

The HMDS reactions occurred in an organic solvent slurry under nitrogen. Using statistical experimental design, …

Investigations Of A Phenanthroline-Based Azo Dye Ligand And Of Re(I) And Ru(Ii) Complexes Based On This Ligand, Yan Zhang

Masters Theses

A 1,10-phenanthroline based azo dye ligand, phen-azo-phenol, produced by diazotizing 5-amino-1,10-phenanthroline (5-NH₂-phen) and then coupling to phenol, and several transition metal complexes containing this ligand, have been synthesized and characterized. The phen-azo-phenol ligands attach to Re(I) and Ru(II) through the phenanthroline linkage to form stable polypyridyl complexes. These complexes show greatly enhanced absorption properties in the visible region when compared to the well-known analogous bipyridine and phenanthroline containing complexes. The visible light absorption of the free ligand and the complexes containing this ligand are greatly affected by the position of the deprotonation equilibrium of the -OH group on …

Synthesis, Characterization And Photophysical Behavior Of A Cr(Iii) Bimetallic System, Yan Chen

Masters Theses

Many binuclear transition metal complexes have been studied to understand the nature of interactions between the metal centers. People have found Simultaneous Pair Excitation phenomenon in some bimetallic system that can serve as a potential source of Non-Linear Optical behavior.

Thus a series of Cr₂ -([14]aneN₄)₂-X₄ⁿ⁺ complexes were synthesized and characterized. Only the cis,cis configuration was found. The results were compared with those of their monomer analogs. The electronic structures are very similar in both monomer and dimer complexes. The quantum yield, UV-Vis absorption and lifetime studies suggested a possible coupling between the …

Nickel Subsulfide Can Protect Human Fibroblasts From The Mutagenic Effect Of Benzo[A]Pyrene Diolepoxide, Samir M. Hamdan

Masters Theses

Cancer researchers are interested in identifying the environmental causes and synergistic influences of different carcinogens. It is important to examine the combined effect of multiple carcinogens since this is a more realistic representation of the true environmental situation in which we are exposed daily. Our study has reported that pretreating human fibroblasts with nickel subsulfide followed by the simultaneous treatment with both nickel subsulfide and benzo[a]pyrene diolepoxide (BPDE) can protect human fibroblasts from the mutagenic effects of BPDE. These results correlate well with our previous chromium-BPDE co-treatment work, suggesting a transition metal dependent protective effect. This protective effect was dependent …

Separation And Determination Of Monochlorophenols By Capillary Zones Electrophoresis, Zarina Yasmin Banu

Masters Theses

Chlorine has been widely used in industry. One of the most common uses of chlorine is in municipal water treatment plants. Chlorine reacts with a variety of organic compounds, among these are phenol and its derivatives which are commonly found in natural waters. When these compounds react with chlorine, a variety of chlorine substituted and oxidized products result depending on concentrations, pH, and temperature. In order to study these reactions it is necessary to separate and determine the various products produced.

Earlier studies have shown 3-chloro and 4-chlorophenol cannot be separated by commercial GLC columns. GC/MS (electron impact) measurements cannot …

Improvement Of Epa Method 8330: Complete Separation Of Explosives Using A Two Phase Approach, Michael J. Lang

Masters Theses

A wide range of primary and secondary contaminants is found in environmental matrices containing explosive residues. HPLC methodology for the detection of explosive is now standardized in EPA Method 8330, and represents the most common method currently used for explosive analysis. However, co-elution of some of the analytes occurs even using method 8330. As a result, explosive analysis using HPLC have required the use of a confirmation column in an additional analysis step.

In the current work, all of the compounds in the EPA 8330 explosives list were resolved using a single HPLC separation. While the EPA 8330 HPLC conditions …

Reactions Of Modified Silica Gel Surfaces With Organometallic Compounds: Enhancing Olefin Polymerization Catalysts, Richard E. Diebel Iii

Masters Theses

Pretreated silica gels with distinct silica surfaces containing either isolated silanols, vicinal silanols, siloxanes, or some combinations of the three, were reacted with several organometallic compounds to determine how each compound reacted with the different silica surface species. The organometallic compounds used were trimethylaluminum, triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, methylaluminoxane, dibutylmagnesium, and bis-cyclopentadienyl dimethyl zirconium.

These reacted silica gels were analyzed using diffuse reflectance infrared Fourier transform spectroscopy and ICP-AES elemental analysis. CH/Metal ratios were calculated using specific peaks in the IR spectra to elucidate the surface bonded species. Elemental analysis was used to determine how much metal was bonded …

Characterization Of Petroleum Fog Oil And Vegetable Oil Smokes, Andrew Oliver Larouche

Masters Theses

"Deception and concealment to gain tactical advantage in the battlefield has been an integral part of warfare. Smoke has been a common tool used for signaling, concealment of troop movement and weapon deployment. U.S. Armed Forces have made use of smokes in an organized manner since the 1st world war. Since then various materials such as white phosphorus, zinc chloride, diesel fuel and petroleum oil aerosols have been used to obscure military targets. For the past thirty years fog oil (FO) a medium distillate has been extensively used by the U.S. Armed Forces for generation of obscurant smokes (OS). During …

Pan, Ppn And Mpan Measurements And The Systematic Relationship Between Mpan And Macr At A Semi-Rural Site In Tennessee, George Nouaime

Masters Theses

Simultaneous measurements of peroxymethacryloyl nitrate (MPAN) and its primary and secondary precursors, methacarolein (MACR) and isoprene, were carried out for the first time in July 1995 at a semi-rural site southeast of Nashville. In addition to these compounds, peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), other volatile organic compounds (VOCs) and supporting measurements were also collected in collaboration with other research groups. The mean concentrations of PAN, PPN, MPAN and MACR were found to be 485 pptv, 50 pptv, 30 pptv and 0.290 ppbv respectively. MP AN levels, which closely tracked those of MACR during the day, peaked and dropped earlier …

Elucidation Of The Pathway Required For The Stimulation Of G6pdh Gene Expression By Insulin And Its Mimetics, Asavari Wagle

Masters Theses

Insulin, an anabolic hormone, exquisitely controls cellular physiology and metabolism by modulating the activity of key proteins which regulate metabolic and mitogenic events. Insulin activates several cytosolic proteins via a phosphorylation cascade, but only some of these proteins are required for its specific action. We have elucidated the insulin signal transduction cascade in primary rat hepatocytes, and outlined some of the events that are required for the insulin induced stimulation of glucose-6-phosphate dehydrogenase (G6PDH) gene expression. Using well-characterized and structurally different inhibitors, we show that insulin stimulation of the gene requires the IRS-1/P13K pathway and not the RAS/RAF/MAPK pathway. Gene …

Extraction Of Premafloxacin Radiolabeled With Carbon Fourteen From Loam Soil, Steven Gregory Staskiewicz

Masters Theses

Premafloxacin is a fluoroquinolone antibiotic being developed by Pharmacia & Upjohn for veterinary indications. Since the parent drug and possibly metabolites will be applied to soil through the deposition of animal excreta, many regulatory agencies will require environmental assessment testing. In order to determine if ¹⁴C-premafloxacin would biodegrade in the soil, loam soil was extracted with solvents and C18 solid phase columns were used to isolate the compound after three weeks of incubation. In addition to extracting the soil, production of ¹⁴CO₂ was monitored by trapping the degradation by-product in 2 N NaOH. Liquid scintillation counting of …

Synthesis Of Biologically Active Substituted Chalcones, Kiel Steven Hoff

Masters Theses

Two different synthetic routes to poly-hydroxylated chalcones are investigated. The wittig synthesis and protection of the hydroxyl functionalities by forming the methyl ether followed by the base catalyzed Claissen-schmidt reaction and then deprotection were investigated. It was demonstrated that the protection-condensation- deprotection route was more efficient. The antiviral activity of 2,2', 4' - trihydroxychalcone against the HIV virus is also presented.

Analysis Of Organic Nitrates In Artic Outflow, Deanna Elyea-Piper

Masters Theses

The Arctic Outflow Study (AOS) was a project funded by the National Science Foundation to assess the impact of tropospheric ozone concentrations by the measurement of oxidized nitrogen. Measurements of arctic outflow were made to assess the seasonal cycle of compounds in arctic air and the partitioning of NOy during transport to the North Atlantic region. These photochemically active compounds are elevated in the arctic during the winter and spring because of the lack of photochemical processes to destroy them.

Measurements of PAN, Alkyl nitrates, NOy, NO, NO₂, CO, HNO₃, O₃, and particulate nitrate …