Chemistry Commons^™

The Effect Of Acetone On Calomel Formation On A Mercury Film Electrode Surface In Chloride Medium, F. Ni̇l Ertaş, H. İsmet Gökçel, Hüseyi̇n Tural

Turkish Journal of Chemistry

In the presence of chloride ions, calomel formation takes place on the mercury thin film electrodes under open-circuit conditions, which leads to high base currents and erratic performance in ASV meas- urements. This study describes the effect of chloride concentration on the calomel formation on the surface by following the cathodic peak on the anodic scan. The effect of acetone on the surface reaction and baseline stability was studied. Application of the method with a sea water sample is also given.

The Rate Of Grafting And Some Kinetic Parameters Of The Graft Copolymerization Of Methacrylic Acid On Poly (Ethylene Terephthalate) Fibers With Azobisisobutyronitrile, Meltem Çeli̇k, Mehmet Saçak

Turkish Journal of Chemistry

In this study the rate of grafting and some kinetic parameters of the graft copolymerization of methacrylic acid on poly(ethylene terephthalate) fibers with azobisisobutyronitrile was investigated. The rate of grafting was found to be proportional to the 0.94 and 1.22 powers of initiator and monomer concentrations, respectively. By carrying out the graft copolymerization reaction at four different temperatures ranging from 70 ^oC to 90 ^oC, the overall rate activation energy of the reaction was found to be 130.4 kJ/mol. The overall rate constants were also calculated.

Modification Of Polyester And Polyamide Fabrics By Different In Situ Plasma Polymerization Methods, T. Öktem, N. Seventeki̇n, H. Ayhan, Erhan Pi̇şki̇n

Turkish Journal of Chemistry

In order to increase the hydrophilicities, and therefore to impart soil resistance and to improve dyeability, poly(ethylene terephthalate) (PET) and polyamide (PAm) fabrics were treated in low-temperature plasmas. Five different modification types were applied. Fabrics were directly treated in acrylic acid, water, air, O_2 and argon plasma. The plasma conditions (i.e., exposure time and discharge power) were changed to control the extent of plasma surface modification. Wettability, soil resistance and dyebility of PET fabrics were significantly improved by this method. More hydrophilic surfaces were created by all the methods.

Polarographic Determination Of Fluvoxamine Maleate In Tablets, Fi̇kri̇ye Elmali, Güzi̇n Alpdoğan, Sidika Sungur, Şule Aycan

Turkish Journal of Chemistry

The differential pulse polarographic (DPP) method was developed for the determination of fluvoxamine maleate (I). At pH = 3. 7, (I) give a peak at - 0. 73 V in aqueous solution. The developed method was applied to the assay of the drug substance in commercial tablet formulations. The results were statistically compared with those obtained by reference methods (HPLC and direct current polarographic method) using t- and F- tests at 95 % confidence level.

Electroanalysis Using Differential Pulse Methods And Stripping Techniques., Enda Howard

Masters

Application of a differential pulse waveform to a microelectrode or a rotating disk electrode results in a peaked response for amperometric redox reactions. Based on these observations models were proposed and tested for these methods. Simulations of the models were carried out by inputting the relevant equations into Microsoft Excel. The microelectrode study revealed a good correlation between one model and the numerical derivative of the current following a linear sweep potential waveform. Experimentally the derivative can be obtained numerically following a linear sweep. The alternative differential pulse waveform requires more sophisticated equipment and the response can be affected by …

Enantioselective Complexation Of Amino Acids By 6a-Deoxy-6a-Hydroxyethylamino- Β -Cyclodextrin And Its Metallo-Derivatives In Aqueous Solution, Nicole Van Hoof, Noel Russell, Mary Mcnamara, Raphael Darcy

Articles

Enantioselectivity towards several amino acids by metallo-6A-deoxy-6A-hydroxyethylamino-β-cyclodextrins (metallo- β CDea’s) was investigated by potentiometric titration of the various amino acid/metallo- β CDea systems with NaOH solution. It was shown that the cyclodextrin derivative is capable of distinguishing between enantiomers of amino acid species in the presence of certain metal ions (Co, Ni, Cu and Zn). Ni- β CDea complexes show the most enantioselectivity,whereas for Cu and Co2C-_CDea complexes less selectivity is observed. As expected, Zn- β CDea complexes exhibit no enantioselectivity. Stability and selectivity, however, do not go hand in hand, since the most stable complexes are formed …

Studies Directed At The Synthesis Of Trialkoxysilyl Substituted Nlo Chromophores, Ida J. Kuhr

Browse all Theses and Dissertations

The synthesis of trialkoxyalkyl substituted NLO chromophores has been investigated. The chromophore 2-(7-(3-hydroxydiphenylamino)-9,9-diethyl-2-fluorenyl)-benzothiazole was prepared by a five step process. Bromination of fluorene yielded 2,7-dibromo-fluorene which could be converted to 2,7-dibromo-9,9-diethylfluorene by alkylation with ethyl iodide in DMSO.Reaction of 2,7-dibromo-9,9-diethylfluorene with one equivalent of butyl lithium followed by reaction with DMF provides 2-bromo-7-formyl-9,9-diethylfluorene. Condensation of 2-bromo-7-formyl-9,9-diethylfluorene and 2-aminobenzenethiol in DMSO results in the formation of 2-(7-bromo-9,9-diethyl-2-fluorenyl)benzothiazole. The conversion of 3-hydroxydiphenylamine to 3-benzyloxy-diphenylamine was accomplished with benzyl bromide and potassium carbonate in DMF. A palladium catalyzed coupling of 3-benzyloxydiphenylamine and 2-(7-bromo-9,9-diethyl-2-fluorenyl)benzothiazole provided 2-(7-(3-hydroxydiphenyl-amino)-9,9-diethyl-2-fluorenyl)benzothiazole. Several attempts to alkylate 2-(7-(3-hydroxydiphenylamino)-9,9-diethyl-2-fluorenyl)benzothiazole with trimethoxysilylmethyl chloride …

A Small-System Ensemble Monte Carlo Simulation Of Supersaturated Vapor: Evaluation Of Barrier To Nucleation, K.J. Oh, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

A small-system grand canonical ensemble Monte Carlo method is developed to evaluate cluster size distribution and barrier to the nucleation in a supersaturated Lennard-Jones vapor. The theoretical foundation is a physical cluster theory in which the Stillinger cluster is used as a prototypical physical cluster. Using method of Mayer’s cluster expansion, the cluster–vapor interaction is effectively taken into account. From a separate canonical ensemble Monte Carlo simulation using a test particle method, the averaged volume of the cluster is obtained and is also incorporated in the small-system ensemble simulation. By this implementation our simulation is computationally more efficient compared to …

Heavily Fluorinated Sugar Analogs, Stephen G. Dimagno

Department of Chemistry: Faculty Publications

Heavily fluorinated Sugar analogs of formula

wherein R₁ is selected from alkyl, alkenyl, aryl, CH₂OH, -CH₂-O-alkyl, -CH₂-O-aryl, -CH₂OPO₃H, -CH₂-O-carbohydrate, -CH₂-NH-peptide, or -CH₂-O-peptide; wherein R₂ is selected from hydroxy, -O-carbohydrate, -NH-peptide,

wherein R₃ is selected from H, halogen, lower alkyl, lower alkenyl, lower haloalkyl, lower haloalkenyl, amino, mono- or di-lower alkylamino; wherein R₄ is Selected from amino, hydroxy, alkoxy, or halogen; and wherein R₅ is H or amino. The compounds of formula (I) are useful as antiviral and antineoplastic agents …

Structural And Electrical Characterization Of A Novel Mixed Conductor: Ceo2 - Sm2O3 - Zro2 Solid Solution, W. Huang, P. Shuk, M. Greenblatt, M. Croft, Fanglin Chen, M. Liu

Faculty Publications

solid solutions were synthesized for the first time by the hydrothermal method. The electrical properties of the solid solutions have been studied in air and under reducing conditions. Solid solutions with the fluorite structure were formed in all of the studied range of substitution after calcination at 1500°C. With increasing substitution up to 30 mol %, the electronic conductivity increases under a reducing atmosphere. The solid solution has good mixed electronic and ionic conductivity; the total conductivity is 0.42 S/cm at and 700°C with an estimated ionic conductivity of ca. .

Infrared Spectoscopy And Electrical Conductivity Of Copper(Ii) 4-Aminobenzoate And Iondine-Doped Copper(Ii) 4-Aminobenzoate, Chang Fu Dee

Student Works (2000-2009)

Copper(II) 4-aminobenzoate (CAB), prepared from copper(II) acetate monohydrate and 4-aminobenzoic acid, was a dark green powder. Fourier Transfonn lnfrared (FTIR) spectrum of CAB, recorded as KBr disc, indicated the presence of all bonds and functional groups expected of it, and the absence of hydrogen bonding. Its conductivity at room temperature was 4.2 x 10^-11 Scm^·1. The value increased as temperature decreased indicating metallic behaviour. Density of states at Fenni level, hopping distance, hopping energy and density of charge carriers calculated based on Mon's Variable Range Hopping model (VRH) are 2.65x 10^-22 (eV)^-1 cm^-3, 7.47 x 10^-8 cm, 0.02 eV and …

Investigations On The Conductivity Of Organotin-Doped Polyethyleneoxide Polymer System, Lekshmi Sarojiniamma

Student Works (2000-2009)

Poly(ethylene oxide) (PEO) has been doped with selected organotin compounds. The organotin dopants used were triphenyltin thiocyanate (Ph3SnSCN) and tetramethylammonium dichlorotriphenylstannate [Ph3SnClr[Me4N)•. Tin incorporation in the polymers was established by several physical techniques. The infrared spectroscopic analysis of the Pb3SnSCN - doped electrolyte film showed bands at 2080-2050 cm.·' which are also given by pure Ph3SnSCN. Different concentrations of organotin doped electrolytes were prepared and conductivity studies on these were perfonned using impedance spectroscopy. From the measurements it was found that the best conductivity of 7.6xJ0.g Siem was obtained for the composition with PEO :dopant ratio of90:10 at room temperature. …

Isolation And Identification Of Sterols In Palm Oil And Their Analysis By Gc Adn Gc-Ms, Ai Chen Han

Student Works (2000-2009)

The unsaponifiablc matters were separated from crude palm oil, crude palm kernel oil, and crude palm fibre oil. The sterol fractions were isolated by preparative thin layer chromatography and were then analysed by gas chromatography and combined gas chromatography-mass spectrometry. Qualitative separations of sterols are illustrated. Tables are presented showing the sterol composition determined in the oi ls, values obtained for individual contents are in broad agreement with other published results There were no major differences between crude palm oil, crude palm kernel oil and crude palm fibre oil with respect to their sterols oomposition. P-sitosterol was found as the …

Method Development And Validation For Drug Analysis By Hplc Gc-Ms, Yann Jen Goh

Student Works (2000-2009)

Enalapril and its metabolite Enalaprilat were determined by gas chromatography - mass spectrometry (GC - MS) and high - performance liquid chromatography (HPLC). For HPLC, the detection limit of enalapril and enalaprilat was 10n g/ml in methanol, whereas for the GC - MS, the detection limit was 6.25ng/ml in plasma. These methods were compared and GC - MS was selected for routine analysis. Enalapril and Enalaprilat in plasma were extracted and cleaned up by using Sep - Pak C 18. Enalapril and Enalaprilat were detected after reaction with diazomethane and were identified by gas chromatography - mass spectrometry as methyl …

Method Development By Hplc For Separation Of Various Hydrocarbon Groups In Coal Samples From Batu Arang, Selangor, Yong Chee Hui Audrey

Student Works (2000-2009)

A preliminary work involving method development for normal stationary phase (silica) pennits the high-performance liquid chromatographic separation or aliphatic and polyaromatic hydrocarbon (PAHs) classes. The Soxhlet extraction method was applied on the coal rock samples and normal phase (silica) short column clean-up separation from highly polymeric material in the coal extract. Method developed on analytical and preparative normal phase silica HPLC columns were to fractionate coal rock extracts, isocratic elution of hexane: ethyl acetate (95 :5, V:V) was found to be quite a good mobile phase. An alternative fractionation method, preparative thin layer chromatography (TLC), was also investigated to separate …

Analysis Of Selected Trace Metals In Water Using Differential Pulse Polarography And Anodic Stripping Voltammetry, Kar Yi Tong

Student Works (2000-2009)

In this project, two types of the electroanalytical methods have been studied, which are the Differential Pulse Polarography_ (DPP) and Differential Pulse Stripping Voltammetry (DPSV). The DPP mode is used to identify the half-wave potential for the metals, including the lead, cadmium, and zinc. The DPP mode is also used to determine the detection limits for the lead, cadmium, and zinc. Meanwhile, the DPSV mode is used to identify the half-wave potential for the metals. The optimum conditions for the DPSV has to be determined, in order to be used to determine the concentrations of the lead, cadmium, and zinc …

A Study Of Traffic Noise From Selected Urban And Suburban Areas, Savitri Ramiah

Student Works (2000-2009)

The main aim of this study is to determine the noise levels in selected urban and suburban roads and to compare the difference in traffic noise levels between these areas. 1be noise attenuated by noise barrier was also surveyed as a small portion of this study. Analysis of traffic noise was surveyed at five locations. Two locations were surveyed for the urban area and two locations for the suburban area and one location for noise barrier. The traffic volume for the duration of the survey was also recorded. Both day time and night time noise levels were studied. The survey …

Gas Chromatographic-Mass Spectrometric Analysis Of Captopril And Its Application In Pharmacokinetic Studies In Healthy Subjects, Zamri Chik

Student Works (2000-2009)

Captopril is a highly specific competitive inhibitor of the angiotensin-convening enzyme (ACE). This enzyme converts angiotensin I, a relatively inactive decapeptide, to angiotensin II , a potent endogenous vasoconstrictor substance. Captopril is widely used for the treatment of hypertension and congestive heart failure. This drug, which contains a sulphydryl group binds readily to albumin and to other plasma proteins. Captopril is unstable in blood and plasma ex vivo because of the reactivity of sulphydryl group which results in oxidation and rapid formation of disulphides. Therefore a fixative or a stabiliser must be added to each blood sample immediately following collection. …

Direct Titrimetric Determination And Of Sulphate, Chee Kin Tan

Student Works (2000-2009)

Interference by foreign ions in direct titrimetric determination of sulphate with barium perchlorate using dimethylsulphonazo III (DMSA Ill) as indicator were studied in this research project. The use of certain water miscible solvents as titration medium has enhanced the determination of end-point. Among the methanol, ethanol, n-propanol and acetone used in the investigation, it was found that medium containing 40 to 50% n-propanol or acetone delivered distinct end-points. The effects of nine cations and eight anions were studied in the above sulphate titration. It was found that the interference caused by Li",Na",K",Mg2"·Mn2", Cd2", NH4", CI and Br are not significant. …

Electrodeposition Of Copper On Polished Copper Electrode, Jia Tsung Ling

Student Works (2000-2009)

This project studies the surface morphology of the copper deposit from three different bath solutions on polished copper (3.1 mm in diameter) electrode by using Scanning Electron Microscopy. The behaviour of glycine as an additive in a bath solution containing 0.3 M of copper (II) sulphate and 2.2 M of sulphuric acid was studied by using cyclic voltammetry. In this project, glycine did not involved directly in the reaction of CU²⁺/CU couple but increased the potential and current density of the plating process. However, glycine has the properties for inhibiting the deposition of copper onto the copper disc. Moreover, block …

Beyond The Dipole Approximation: Angular-Distribution Effects In The 1s Photoemission From Small Molecules, Dennis W. Lindle, Oliver Hemmers, H. Wang, P. Focke, I. A. Sellin, J. D. Mills, J. A. Sheehy, P. W. Langhoff

Environmental Studies Faculty Publications

Over the past two decades, the dipole approximation has facilitated a basic understanding of the photoionization process in atoms and molecules. Recent experiments on the 1s inner shells of small molecules at relatively low photon energies (⩽ 1000 eV) show strong nondipole effects. They are significant and measurable at energies close to threshold, in conflict with a common assumption that the dipole approximation is valid for photon energies below 1 keV.

Interactions Of Ti(Iv) And Sn(Iv) Organometallic Complexes With Double-Stranded Dna, Katherine Macdonald Davies

Honors Theses

In order to understand further the interactions that exist between specific organometallic complexes and DNA, reactions of double-stranded calf-thymus DNA with bis(cyclopentadienyl)titanium dichloride [Cp₂TiC1₂] (TDC), bis(t-butylcyclopentadienyl)titanium dichloride [(C₄H₉Cp)₂TiC1₂] (r-butyl TDC), bis(i-propylcyclopentadienly)titanium dichloride [(C₃H₆Cp)2TiCl₂ a-propyl mc), bis(pentamethylcyclopentadienyl) titanium dichloride [(Cp"₂TiC1₂ (pentarnethyl TDC), triphenyltin chloride (Ph₃SnCl), diphenylrin dichloride (Ph₂SnC1₂) , and triphenyltin acetate (Ph₃SnOAc) were performed. The goal of this research is to establish how the fundamental structure and composition of these compounds determine the effecti veness of their DNA interactions. Each metal compound was incubated with calf thymus DNA at several metal: DNA ratios and reactions were maintained at 37°C 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 …

Electrophilic Aromatic Nitrosation. Isolation And X-Ray Crystallography Of The Metastable No+ Complex With Nitrosoarene, Sergey V. Lindeman, E. Bosch, Jay K. Kochi

Chemistry Faculty Research and Publications

Isolation of the unstable 1∶1 complex of 4-nitrosoanisole with NO⁺PF₆⁻ allows its precise X-ray structural characterization. The charge-transfer crystal is formed via strong N⋯N coordination [the distance of 1.938(5) Å corresponding to a σ-bond order of ≈0.2] in the mean plane of the planar 4-nitrosoanisole donor. Thorough analysis of its molecular geometry in terms of valence resonance and MO schemes reveals a strong charge polarization with a local negative charge localized on the nitroso group and a local positive charge distributed over the adjacent p-methoxybenzyl moiety. Such a charge distribution accommodates the well-known passivation of …

Novel (Heteromolecular) Π-Complexes Of Aromatic Cation Radicals. Isolation And Structural Characterization, P. Le Maguères, Sergey V. Lindeman, Jay K. Kochi

Chemistry Faculty Research and Publications

Extensive (electron) delocalization in the novel heteromolecular π-complex of the hindered naphthalene cation radical (OMN^+•) with naphthalene (NAP) accompanies the pronounced charge-transfer absorption band at ∼1100 nm in the near-IR. X-ray crystallography establishes the viability of the unusual “club sandwich” structure despite the repulsive electrostatic forces inherent to the dicationic unit.

Cross-Linking Of Polystyrene By Friedel-Crafts Chemistry: Multi-Functional Additives, Hongyang Yao, Jin Zhu, Michael A. Mckinney, Charles A. Wilkie

Chemistry Faculty Research and Publications

Various multifunctional aromatic compounds were synthesized and tested to ascertain if they were able to cross-link polystyrene. Catalysis and inhibition at high temperature were studied to achieve control over the cross-linking temperature, in order to develop suitable formulations which may function as flame retardants.

On The Stabilizing Action Of Protein Denaturants: Acetonitrile Effect On Stability Of Lysozyme In Aqueous Solutions, Evgenii L. Kovrigin, Sergey A. Potekhin

Chemistry Faculty Research and Publications

Stability of hen lysozyme in the presence of acetonitrile (MeCN) at different pH values of the medium was studied by scanning microcalorimetry with a special emphasis on determination of reliable values of the denaturational heat capacity change. It was found that the temperature of denaturation decreases on addition of MeCN. However, the free energy extrapolation showed that below room temperature the thermodynamic stability increases at low concentrations of MeCN in spite of the general destabilizing effect at higher concentrations and temperatures. Charge-induced contribution to this stabilization was shown to be negligible (no pH-dependence was found); therefore, the most probable cause …