Physical Sciences and Mathematics Commons^™

Reaction Mechanism And Kinetics Of Aqueous Solutions Of Primary And Secondary Alkanolamines And Carbon Dioxide, Olgac Bavbek, Erdoğan Alper

Turkish Journal of Chemistry

The mechanism and kinetics of the reaction between aqueous solutions of CO_2 and the alkanolamines 1-amino-2-propanol, 3-amino-1-propanol,2-methyl aminoethanol and 2-ethyl aminoethanol were investigated using a stopped flow technique. It was found that the reaction orders according to power law kinetics were between 1.1 and 2.0, depending on the alkanolamine and the concentration ranges investigated. This fractional order was therefore considered to be further evidence that carbamate formation takes place according to a zwitterion mechanism rather than a one-step reaction. The kinetic rate parameters for these alkanolamines were evaluated from experimental data at 303 K according to this mechanism.

Acidity Of Silica-Alumina Catalysts By Amine Titration Using Hammett Indicators And Ft-Ir Study Of Pyridine Adsorption, Mürüvvet Yurdakoç, Mehmet Akçay, Yalçin Tonbul, Kadi̇r Yurdakoç

Turkish Journal of Chemistry

In this study, characterization and surface acidity of Siral (SiO_2-Al_2O_3) compounds were investigated with Hammett acidity functions, the n-butylamine titration method and FTIR analysis of the spectra of pyridine adsorption. All the samples had an acid strength of H_0\leq+2.8. The calculated total amount of acid of the samples increased with the increase in SiO_2 content up to Siral 40 and then decreased sharply in the case of Siral 80. Maximum amount of acidity was observed in the case of Siral 40 as 1.37mmole/g. No evidence was found for a band at 1540 cm^{-1} on Pural indicating that there were no …

Chemical Investigation Of The Sponge Verongia Aerophoba, Zeynep Aydoğmuş, Nebi̇ye Ersoy, Sedat İmre

Turkish Journal of Chemistry

The solvent effect on Verongia aerophoba metabolites during the extraction and isolation processes were examined in this study. A major compound (6), a stereoisomer of fistularin-3, and a new compound (2) were isolated from the acetone extract of dried and ethanol extract of fresh V. aerophoba samples respectively. The structures of these metabolites were elucidated using spectroscopic methods.

Development Of Black Cobalt Selective Absorber On Copper For Solar Collectors, Fi̇gen Kadirgan, Mete Söhmen

Turkish Journal of Chemistry

An eletrolyte is proposed for the deposition of black cobalt selective absorber coating on copper plate. The influence of the electrolyte composition and operating parameters on the properties of black cobalt coatings including optical properties were studied. The optimum conditions to obtain a high absorptance/emittance ratio are described.

Comparative Mechanistic Studies On The Oxidation Of Aromatic And Aliphatic Hydroxyl Derivatives In An Alkaline Medium At Preanodized Pt, Au And Pt/Au Electrodes In Presence Of Redox Mediators, Sasha Kalcheva, Philip Iotov

Turkish Journal of Chemistry

The role of redox mediators obtained from Pt, Au, and Pt/Au electrodes in the process of electrocatalytic oxidation of aromatic/aliphatic hydroxyl derivatives in an alkaline medium has been studied by applying cyclic voltammetry. Phenol and glycerol were used as aromatic and aliphatic hydroxyl derivatives in the electrochemical oxidation experiments. The results revealed that the presence of redox mediators formed by preliminary electrode anodization is crucial for the process of oxidation of aromatic compounds and imposes a different oxidation route for the aliphatic hydroxyl derivatives. The effect of preanodization has been related to the formation and dissolution of the corresponding higher …

Electrochemical Characterization Of Al_2 O_3 -Ni Thin Film Selective Surface On Aluminium, Fi̇gen Kadirgan, Ewa Wackelgard, Mete Söhmen

Turkish Journal of Chemistry

Solar thermal collectors represent a widely used type of system for the conversion of solar energy. In order to produce selective coatings on aluminium substrates to be used as absorber plates in high efficiency solar collectors, nickel pigmentation was applied to anodically oxidised surfaces. Electrochemical dc methods are used to study the oxidation of aluminium as functions of the following electrolysis conditions: applied current, pH, temperature and concentration of electrolyte. The properties of the oxidised aluminium surfaces are investigated by cyclic voltammetry. Nickel pigmentation of porous aluminium surfaces was also performed as a function of electrochemical pigmentation conditions by ac …

The Effects Of Detergent Pollution On The Corrosion Of Iron And Aluminium, Si̇bel Zor, B. Yazici, M. Erbi̇l

Turkish Journal of Chemistry

The current-potential values were measured with iron or aluminium electrodes in solutions of 3.5% NaCl containing 30, 150, 300 ppm linear alkylbenzene (LAB) and detergents (LAS) at pH8. Polarization resistances (Rp) were determined using the values of current and potentials. The corrosion rates of iron and aluminium were determined in 2 and 4 hour intervals using the Mansfeld-Oldham equation based on the Stern-Geary and Butler-Volmer equations.

Reactions Of N-Aminopyrimidine Derivatives With 1,3-Dicarbonyl Compounds, Zülbi̇ye Önal, Behzat Altural

Turkish Journal of Chemistry

The reactions of 1-Amino-pyrimidine derivatives (1) and some 1,3-dicarbonyl compounds (2) were realized in the presence of p-toluensulfonic acid catalyst to give convenient enamine (3) and/or imine derivatives (4). In the same way, the enamine (5) and/or imine derivatives (6) were synthesized using (1) and 1,3-indanedione which is one of the different 1,3-dicarbonyl compounds. The molecular structures of all the prepared compounds were determined by ^1H-nmr, ^{13}C-nmr, i.r. spectra and elemental analyses, and were drawn by taking imine-enamine tautomerism into account.

A Modified Potentiometric Method For The Estimation Of Phenol In Aqueous Systems, Farhat Huma, Muhammad Jaffar, Khalid Masud

Turkish Journal of Chemistry

A modified potentiometric titration is proposed for the estimation of phenol in aqueous systems. The method is evolved on the basis of a critical dependence of pH on log V rather than simple V, as used in conventional potentiometric titrations. The method incorporates titrants in a concentration range several orders of magnitude greater than that of phenol in the aqueous phase. Derivative potentiometric curves so obtained provide a clear exposition of the equivalence point and the overall error is found to be between \pm 1.0 and 1.5%. The range of phenol concentration investigated was from 10^{-2} to 10^{-3} M. and …

Electrochemical Behaviour Of Hexa[4-(Phenylazo) Phenoxy]Cyclotriphasphazene, Necati̇ Menek, Günseli̇ Turgut, Mustafa Odabaşioğlu

Turkish Journal of Chemistry

The polarographic and voltammetric behaviour of hexa[4-(phenylazo)phenoxy]cyclotriphasphazene in tetrahydrofuran-water 50% (v/v) was studied at room temperature using various electrochemical techniques. In this study, the reduction of the azo group to the amino group of the organophosphazenes compound was observed as the electrode reaction. An electrode reaction mechanism was suggested for the compound.

Synthesis, Structural And Thermal Studies Of Titanium(Iv) Complexes Of N-Alkyl Phenothiazines, Jaldappa Seetharamappa, Boregowda Keshavan

Turkish Journal of Chemistry

New coordination compounds of the type [Ti(C_2O_4)_2L]2H_2O where L=N-alkyl phenothiazines (NAPs) were synthesised and characterised by elemental analyses, molar conductance, magnetic, thermal and spectral data. The spectral data suggest the bidentate nature of NAPs in the complexes. An octahedral structure is proposed for all the complexes. Thermal studies were used to evaluate the kinetic and thermodynamic parameters.

The Display Of Photographic-Quality Images On The Web: A Comparison Of Two Technologies, Chiang S. Jao, Daniel B. Hier, Steven U. Brint

Chemistry Faculty Research & Creative Works

Downloading Medical Images on the Web Creates Certain Compromises. the Tradeoff is between Higher Resolution and Faster Download Times. as Resolution Increases, Download Times Increase. High-resolution (Photographic Quality) Electronic Images Can Potentially Play a Key Role in Medical Education and Patient Care. on the Internet, Images Are Typically Formatted as Graphics Interchange Format (GIF) or the Joint Photographic Experts Group (JPEG) Flies. However, These Formats Are Associated with Considerable Data Loss in Both Color Depth and Image Resolution. Furthermore, These Images Are Available in a Single Resolution and Have No Capability of Allowing the User to Adjust Resolution as Needed. …

Separation Of Enantiomers By Capillary Electrophoresis Using Pentosan Polysulfate, Xiande Wang, Jauh Tzuoh Lee, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Pentosan polysulfate, a semisynthetic polysaccharide, was employed as a chiral un buffer additive in capillary electrophoresis. Twenty-eight racemic analytes were resolved. The separations were successful only at low pH when the analytes were significantly protonated. This suggests that ionic interactions were the dominant associative interactions between the anionic pentosan polysulfate and the positively charged analytes. Compared to other linear, carbohydrate-based chiral selectors (i.e., chondroitin sulfates, heparin and dextran sulfate) pentosan polysulfate has some characteristics common of anionic polysaccharides; yet it has several differences in its structure and properties which account for its unusual enantioselectivity. The effects of pH, concentration of …

Avoparcin, A New Macrocyclic Antibiotic Chiral Run Buffer Additive For Capillary Electrophoresis, K. Helen Ekborg-Ott, Gina A. Zientara, Jeffrey M. Schneiderheinze, Kyung Gahm, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Avoparcin, like vancomycin, teicoplanin, and ristocetin A, belongs to the family of macrocyclic glycopeptide antibiotics. These antibiotics have all been used as effective chiral selectors for capillary electrophoresis (CE), thin-layer chromatography (TLC), and high-performance liquid chromatography (HPLC). The present work focuses on avoparcin, which has been shown to be an excellent chiral selector for the CE enantioseparation of many N-blocked amino acids, as well as several anti-inflammatory drugs of pharmaceutical importance. The use of avoparcin as a chiral run buffer additive in CE is discussed, as well as the effects of changing experimental parameters, like avoparcin concentration, pH, organic modifiers, …

1-Hydroxyethyl-2,2′-Biimidazole, Geng Lin, Harvest L. Collier, Russell G. Baughman

Chemistry Faculty Research & Creative Works

The two imidazole rings in the title compound, C₈H₁₀N₄O, are almost coplanar, having an angle of 2.3 (2)° about the C-C bond connecting the rings. the conformation adopted is such that the nitrogen substituents (-H and -CH₂CH₂OH) are in a trans orientation. the molecules are connected by intermolecular O-H. . .O and N-H. . .N hydrogen bonds to yield an arrangement of pairs of molecules reminiscent of side-by-side stacks of crinkled ribbon.

Pyrene Labeled Poly (Aryl Ether) Monodendrons: Synthesis And Photophysical Studies, Wajiha Adnan Khan

Seton Hall University Dissertations and Theses (ETDs)

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Synthesis Of Novel Sesquiterpene Lactones: Heritianin, Vallapianin And Vallapin, Kostas Gavardinas '99

Honors Projects

For decades considerable research has focused on improving the efficiency of crop protection. Many naturally occurring biodegradable compounds have often been used as pesticides and with increased environmental concerns, the identification of biologically active natural products has attracted significant attention. Fish toxicity has often been used as a measure of pesticidal activity. Several Southeast Asian mangrove species have been shown to possess ichthyotoxic properties. A bioassay of the extracts obtained from Heritiera littoralis, a Philippine mangrove plant, indicated toxicity toward fish thus suggesting the possibility of their use as pesticides. Three sesquiterpene lactones, Heritianin, Vallapin, and Vallapianin have been isolated …

Oxidation Of Benzoins To Benzils Using Bismuth(Iii) Nitrate-Copper(Ii) Acetate, Ram Mohan, Steven Tymonko, Bryce Nattier

Scholarship

Benzoins are oxidized to benzils in excellent yields by 0.4 equivalents of Bi(NO3)3.5H20 and 4 mol% of Cu(OAc)23)3.5H20 is a stable, inexpensive, commercially available solid. The relatively low cost and low toxicity of bismuth(Ill) nitrate makes this procedure a particularly attractive method for oxidation of benzoins.

Molecular Organic Geochemistry Of New York Bight Sediments. Sources Of Biogenic Organic Matter And Polycyclic Aromatic Hydrocarbons, Michael A. Kruge

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

As part of a multidisciplinary evaluation of the environmental impact of waste disposal in the New York Bight, a preliminary effort was undertaken to assess the molecular geochemistry of its sedimentary organic matter (OM). For this initial phase of the study, samples were taken from two New York Bight cores collected outside the area of known dumping [in Sandy Hook Bay, NJ], to establish the environmental context for future work on sediments from within dumpsite zones. The method employed was flash pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), which is an organic microanalysis technique suitable for solid samples, in this case dried, raw …

On-Road Remote Sensing Of Automobile Emissions In The Chicago Area: Year 2, Peter J. Popp, Gary A. Bishop, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

On-Road Remote Sensing Of Automobile Emissions In The Denver Area: Year 1, Peter J. Popp, Sajal S. Pokharel, Gary A. Bishop, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

Rsd Studies In Austin, 1998, Sajal S. Pokharel, Donald H. Stedman, Gary A. Bishop

Fuel Efficiency Automobile Test Publications

No abstract provided.

Real-Time Remote Sensing Of Snowmobiles Emissions At Yellowstone National Park: An Oxygenated Fuel Study, 1999, Jerome A. Morris, Gary A. Bishop, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

Remote Sensing Of Railroad Locomotive Emissions: A Feasibility Study, Peter J. Popp, Gary A. Bishop, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

Comparison Of Methods For Calculating The Properties Of Intramolecular Hydrogen Bonds. Excited State Proton Transfer, T. Kar, Steve Scheiner, M. Cuma

Chemistry and Biochemistry Faculty Publications

A series of molecules related to malonaldehyde, containing an intramolecular H-bond, are used as the testbed for a variety of levels of ab initio calculation. Of particular interest are the excitation energies of the first set of valence excited states, nπ^∗ and ππ^∗, both singlet and triplet, as well as the energetics of proton transfer in each state. Taking coupled cluster results as a point of reference, configuration interaction-singles–second-order Møller–Plesset (CIS–MP2) excitation energies are too large, as are CIS to a lesser extent, although these approaches successfully reproduce the order of the various states. The …

New Polyether Toxins From Shellfish And Marine Phytoplankton: Isolation Studies And Development Of Analytical Methods, Alan G. Bishop

Theses

There are three classes of polyether toxins responsible for Diarrhetic Shellfish Poisoning (DSP) world-wide. The causative toxins are okadaic acid (OA) and derivatives (DTXs), pectenotoxins (PTXs) and yessotoxins (YTXs). The origin of these toxins are phytoplankton from Dinophysis or Prorocentrum spp. OA has been demonstrated for most outbreaks in Europe and more recently a new isomer DTX-2 has been reported in Ireland.

Marine phytoplankton biomass samples consisting predominantly of Dinophysis acuta, were acquired using a large double plankton net from waters off the South-west coast of Ireland. Analysis of unialgal samples using high performance liquid chromatography (HPLC) with fluorescence and …

The Revovery Of Copper And Cobalt From Oxidized Copper Ore And Converter Slag, Berri̇n Zi̇yadanoğullari, Recep Zi̇yadanoğullari

Turkish Journal of Chemistry

The aim of this study was to develop a method for obtaining copper and cobalt from oxidized copper ore and converter slag. In order to convert the copper and cobalt into sulfate compounds the main step was to roast the samples obtained by sulfurization and transfer the samples into solution. First the oxidized copper ore was roasted, followed by the mixture of converter slag and oxidized copper ore. Since the levels of copper and cobalt were low, the sulfurization process was carried out under autoclave conditions. The samples obtained were roasted. The yields of copper and cobalt passed into the …

Electrochemical Preparation And Sensor Properties Of Conducting Polyaniline Films, M. Özden Eki̇nci̇, Ergün Eki̇nci̇, A. Ersi̇n Karagözler

Turkish Journal of Chemistry

A polyaniline-glucose oxidase electrode was prepared by the electrochemical polymerization of aniline on a Pt electrode that was already pre-adsorbed by the enzyme (glucose oxidase) at a potential of 1 V vs. Ag/AgCl. Then, the amperometric responses of the enzyme electrode to the electroactive hydrogen peroxide formed by the enzyme-catalyzed reaction of the substrate (glucose) with oxygen were measured at a potential of 0.7 V in PBS solution. The effects of electrochemical polymerization (i.e., concentrations of monomer and electrolyte, film thickness) and amperometric measurement parameters (i.e. pH, temperature) on the amperometric response characteristics to glucose of the resultant enzyme electrode …

An Investigation Of The Formation Mechanism Of Allene Or Alkyne In The 6,7-Benzobicyclo[3.2.1]Octane System By Deuterium Labeling Experiments, Yavuz Taşkesenligil, Ferhan Tümer, Cavi̇t Kazaz, Meti̇n Balci

Turkish Journal of Chemistry

In order to reveal the real intermediate in the base-promoted reaction of 1, 3-bromo-4,4-dideuterio-6,7-benzobicyclo[3.2.1]octa-2,6-diene 10 was synthesized and its HBr elimination reaction studied. Reaction of 10 with potassium tert-butoxide yielded butoxyl ether 18 in which proton-deuterium exchange has occured.

Reaction Of Tribromonitromethane With Aldehydes And Ketones In The Presence Of Zn Metal In Aqueous Medium, Ali̇ Shaker Mahasneh

Turkish Journal of Chemistry

Aldehydes and ketones react with tribromonitromethane in the presence of zinc metal dust, ammonium chloride and water to give dibromonitroalcohols in good yields.