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1999

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Electrooxidation Of Linear Alkyl Benzene Sulfonate (Las) On Pt Electrodes, Bi̇rgül Yazici, Si̇bel Zor Jan 1999

Electrooxidation Of Linear Alkyl Benzene Sulfonate (Las) On Pt Electrodes, Bi̇rgül Yazici, Si̇bel Zor

Turkish Journal of Chemistry

The electrochemical behaviour of linear alklybenzene sulfonate (LAS) on Pt electrodes was investigated in 0.05M Na_2SO_4 and in 0.1M NaCl at pH=8 by the potentiokinetic method and by electrolysis. The anodic and cathodic semilogarithmic current-potential curves were obtained between -1.6V - +1.6V. The experimental discharge potentials were determined by means of current-potential-curves obtained by electrolysis between 0-3V. The percentages of surface active material remaining in the solution after specified periods (0-6hrs) were determined for different initial concentrations of LAS (30, 150, 300 ppm) by using a potentiostat at +1.6V and by applying a potential of 20V via a direct current …

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The Application Of A Scanning Electron Microscope With An Energy Dispersive X-Ray Analyser (Sem/Edxa) For Gunshot Residue Determination On Hands For Some Cartridges Commonly Used In Turkey, Kezban Gökdemi̇r, Ertan Seven, Yüksel Sarikaya Jan 1999

The Application Of A Scanning Electron Microscope With An Energy Dispersive X-Ray Analyser (Sem/Edxa) For Gunshot Residue Determination On Hands For Some Cartridges Commonly Used In Turkey, Kezban Gökdemi̇r, Ertan Seven, Yüksel Sarikaya

Turkish Journal of Chemistry

The primers of the 10 commonly used cartridges in Turkey, MKE MP5, GECO Luger, FC Luger, WIN Luger, S&B Luger, WRA Luger, FNB Luger, P Luger, KF 80 Luger and SINTOX ACTION Luger were first examined with a SEM/EDXA. Then these cartridges used in test firings and the GSR on the hands of the test shooters was collected using adhesive-coated sample stubs and examined with a SEM/EDXA. Samples were scanned by viewing the BSE (Backscattered electron) image and, brighter and spherical particles were located, and then analysed with an EDXA. The elemental compositions of the GSR of the studied cartridges …

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Electrochemical Preparation And Sensor Properties Of Conducting Polyaniline Films, M. Özden Eki̇nci̇, Ergün Eki̇nci̇, A. Ersi̇n Karagözler Jan 1999

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 …

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Nepetalactones And Other Constituents Of Nepeta Nuda Ssp. Albiflora, Gamze Kökdi̇l, Sabi̇ha M. Yalçin, Gülaçti Topçu Jan 1999

Nepetalactones And Other Constituents Of Nepeta Nuda Ssp. Albiflora, Gamze Kökdi̇l, Sabi̇ha M. Yalçin, Gülaçti Topçu

Turkish Journal of Chemistry

The hexane extract of Nepeta nuda ssp. albiflora led to the isolation of six known monoterpene nepetalactones, 4a\alpha,7\alpha,7a\alpha-nepetalactone (1), 4a\alpha,7\alpha,7a\beta-nepetalactone (2), 4a\beta,7\alpha,7a\beta-nepetalactone (3), 4a\beta,7\alpha,7a\alpha-nepetalactone (4), 4a\alpha,7\beta,7a\beta-nepetalactone (5), 3\alpha-hydroxy-4a\alpha,7\alpha,7a\alpha-dihydron\-epe\-tal\-actone (=nepetalic acid) (6) and a dimeric 5,9-dehydronepetalactone (7) along with two known steroids \beta-sitosterol and sitosterol 3-one and a triterpene betulinic acid. The acetone extract of the same plant afforded compound 7 in a higher yield in addition to compounds 2 and 6, and sesquiterpene caryophyllene oxide, the iridoid glucoside 1,5,9-epideoxyloganic acid, the triterpenoids oleanolic, ursolic and betulinic acids, and sitosterol 3\beta-glucoside.

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Nonyl-And Dodecylamines Intercalated Bentonite And Illite From Turkey, Gülten Akçay, M. Kadi̇r Yurdakoç Jan 1999

Nonyl-And Dodecylamines Intercalated Bentonite And Illite From Turkey, Gülten Akçay, M. Kadi̇r Yurdakoç

Turkish Journal of Chemistry

Bentonite and illite were interacted with nonyl- and dodecylammonium salt solutions to see how the alkylammonium ions became attached and oriented within the interlamellar space of the clays. X-ray diffraction analyses were carried out to obtain information on the interlamellar organization and orientation of the adsorbed alkylammonium compounds. Thermogravimetric analysis (TG, DTG) and Fourier Transform Infrared Analyses (FTIR) were performed to characterize the samples and to determine the amounts adsorbed by the clay samples. The modification process was effective in nonyl- and dodecylammonium bentonites. Alkylammonium ions were adsorbed in the interlamellar space of the clays. Regarding the orientation of the …

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Cover And Contents Jan 1999

Cover And Contents

Turkish Journal of Chemistry

No abstract provided.

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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 Jan 1999

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.

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Reaction Of Tribromonitromethane With Aldehydes And Ketones In The Presence Of Zn Metal In Aqueous Medium, Ali̇ Shaker Mahasneh Jan 1999

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.

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Synthesis And Properties Of The Phthalocyanines Containing Eugenol (4-Allyl-2-Methoxyphenol), Erbi̇l Ağar, Selami̇ Şaşmaz, Ayşen Ağar Jan 1999

Synthesis And Properties Of The Phthalocyanines Containing Eugenol (4-Allyl-2-Methoxyphenol), Erbi̇l Ağar, Selami̇ Şaşmaz, Ayşen Ağar

Turkish Journal of Chemistry

New metal-free and metallophthalocyanines (M=Cu(II), Ni(II), Co(II), Zn(II) and Fe(II)) substituted with eugenol (4-allyl-2-methoxyphenol) from 1,2-dicyano-4-nitrobenzen are described. Cyclotetramerization of the substituted phthalonitrile leads to a product very soluble in common organic solvents. The characterization of the compounds was accomplished by elemental analysis, ^1H NMR, ^{13}C NMR, IR and UV-VIS spectral data.

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Stabilities Of Complexes Of Scandium(Iii) And Yttrium(Iii) With Catechol Derivatives, Naci̇ye Türkel, Rahmi̇ye Aydin, Ulvi̇ye Özer Jan 1999

Stabilities Of Complexes Of Scandium(Iii) And Yttrium(Iii) With Catechol Derivatives, Naci̇ye Türkel, Rahmi̇ye Aydin, Ulvi̇ye Özer

Turkish Journal of Chemistry

The interactions of scandium(III) and yttrium(III) ions with catechol derivatives; catechol(H_2L, CAT), 4-nitrocatechol(H_2L, 4NCAT) and 2,3-dihydroxynaphthalene- 6-sulphonic acid(H_2L, DHN) were investigated in different metal ion:ligand mole ratios, by potentiometry and spectrophotometry. The stoichiometries of formed complexes have been defined by Job's method and formation curves have been drawn for some complexes, whenever possible. The stability contants of the fourteen formed complexes in definite stoichiometries have been determined, in an ionic medium of 0.1M KNO_3 or NaClO_4 at a temperature of 25°C. Noticeably, complexes of scandium(III) ion formed at much lower pH values than complexes of yttrium(III) ion, and its catechol …

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Synthesis, Characterization And In Vitro Degradation Of Poly(Dl-Lactide)/Poly(Dl-Lactide-Co-Glycolide) Films, Menemşe Gümüşdereli̇oğlu, Günday Deni̇z Jan 1999

Synthesis, Characterization And In Vitro Degradation Of Poly(Dl-Lactide)/Poly(Dl-Lactide-Co-Glycolide) Films, Menemşe Gümüşdereli̇oğlu, Günday Deni̇z

Turkish Journal of Chemistry

Poly(dl-lactide) (PLA) homopolymers and poly(dl-lactide-co-glycolide) (PLGA) copolymers were synthesized from their cyclic dimers, i.e. dl-lactide and glycolide, by ring-opening polymerization in the presence of catalyst stannous octoate and chain control agent lauryl alcohol. The effects of catalyst and chain control agent concentrations, reaction temperature, and reaction time on the molecular weight and yield of homopolymers were studied. The homopolymers were obtained in the intrinsic viscosity 0.1 to 1.0 dl/g range by changing the polymerization conditions. The copolymers in two different lactide/glycolide ratios, i.e. 90:10 and 70:30 and in 0.60 intrinsic viscosity were synthesized. The polymers were further characterized by IR, …

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Studies On The Synthesis Of Some Substituted Flavonyl Thiazolidinedione Derivatives-I, Oya Bozdağ, Gülgün Ayhan Kilcigi̇l, Meral Tunçbi̇lek, Rahmi̇ye Ertan Jan 1999

Studies On The Synthesis Of Some Substituted Flavonyl Thiazolidinedione Derivatives-I, Oya Bozdağ, Gülgün Ayhan Kilcigi̇l, Meral Tunçbi̇lek, Rahmi̇ye Ertan

Turkish Journal of Chemistry

Synthesis and some physico-chemical properties of five flavonyl thiazolidinedione derivatives are described. These products were synthesized by Knoevenagel condensation from flavone-6-carboxaldehyde and 3-substituted 2,4-thiazolidinediones.

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A Study Of The Thermodynamic Properties Of Poly [2-(3-Mesityl-3-Methylcyclobutyl)-2-Hydroxyethyl Methacrylate] At Infinite Dilution Using Inverse Gas Chromatography-2-Hydroxyethyl, İsmet Kaya, Kadi̇r Demi̇relli̇ Jan 1999

A Study Of The Thermodynamic Properties Of Poly [2-(3-Mesityl-3-Methylcyclobutyl)-2-Hydroxyethyl Methacrylate] At Infinite Dilution Using Inverse Gas Chromatography-2-Hydroxyethyl, İsmet Kaya, Kadi̇r Demi̇relli̇

Turkish Journal of Chemistry

Some thermodynamic quantities were obtained for the interactions of poly [2-(3-mesityl-3-methylcyclobutyl)-2-hydroxyethyl methacrylate] with alcohols, ketones, acetates, aromatics and alkanes by inverse gas chromatography in the temperature range 160-200°C. The specific retention volumes, V°_g, weight fraction activity coefficients of solute probes at infinite dilution, \Omega^{\infty}_1, Flory-Huggins thermodynamic interaction parameters, \chi^{\infty}_{12} between polymer and solvents were determined. The partial molar free energy, \Delta \bar{G}^{\infty}_{1}, the partial molar heat of mixing, \Delta\bar{H}^{\infty}_1 at infinite dilution and the solubility parameters of the polymer, \delta_2 were calculated.

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Some Chemical Constituents From Marine Algae Of Karachi Coast (Arabian Sea), Muhammad Shaiq Ali, Viqar Uddin Ahmad, Farah Mahzar, Iqbal Azhar, Khan Usmanghani Jan 1999

Some Chemical Constituents From Marine Algae Of Karachi Coast (Arabian Sea), Muhammad Shaiq Ali, Viqar Uddin Ahmad, Farah Mahzar, Iqbal Azhar, Khan Usmanghani

Turkish Journal of Chemistry

Some commonly available marine algae have been collected from the Karachi coast of Arabian Sea for the search of new chemical constituents having biological importance. The structures of purified samples have been elucidated with the aid of modern spectroscopic techniques. Among the known constituents a new metabolite (1) has been isolated from the brown alga Iyengaria stellata.

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Adsorption Of Copper And Cadmium Lons By Activated Carbon From Rice Hulls, Murat Teker, Mustafa İmamoğlu, Ömer Saltabaş Jan 1999

Adsorption Of Copper And Cadmium Lons By Activated Carbon From Rice Hulls, Murat Teker, Mustafa İmamoğlu, Ömer Saltabaş

Turkish Journal of Chemistry

The removal of copper (II) and cadmium (II) ions from aqueous solutions, by adsorption on activated carbon prepared from rice hulls (ACRH), was investigated depending on pH, activated carbon dosage, contact time, initial metal concentration and solution temperature. The optimum values of pH, ACRH dosage and contact time were determined to be 5-8, 0.5 g ACRH/25 mL solution an 60 minutes respctively for the adsorption of Cu (II) ions and 5-8, 1.5 g ACRH/25 mL solution and 60 minutes for the adsorption of Cd (II) ions. From the initial concentrations, the constants for the Freundlich and Langmuir isotherm were calculated …

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Investigation Of Adsorption Isotherms Of Myristic, Palmitic And Stearic Acids On Rice Hull Ash, Hüseyi̇n Topallar, Yüksel Bayrak Jan 1999

Investigation Of Adsorption Isotherms Of Myristic, Palmitic And Stearic Acids On Rice Hull Ash, Hüseyi̇n Topallar, Yüksel Bayrak

Turkish Journal of Chemistry

The adsorption of myristic, palmitic and stearic acids on rice hull ash from isooctane as solvent was studied and conformed to a Langmuir isotherm. Monolayer coverage was determined to be 40.08, 38.43 and 37.27 mg/g, respectively. The free energy of adsorption, \Delta G°_{ads}, for the adsorption was determined to be -6,25, -6.32 and -6.39 kcal mol^{-1} for the adsorbates, respectively. The equilibrium parameter indicated that rice hull ash is a good adsorbent for myristic, palmitic and stearic acids examined.

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Determination Of Activation Energy For The Number Average Degree Of Polymerization Using The Fluorescence Method, Önder Pekcan, Yaşar Yilmaz Jan 1999

Determination Of Activation Energy For The Number Average Degree Of Polymerization Using The Fluorescence Method, Önder Pekcan, Yaşar Yilmaz

Turkish Journal of Chemistry

A novel method based on steady state fluorescence measurements is introduced for measuring the activation energy of the number average degree of polymerization (NADP). Pyrene (Py) was used as a fluorescence probe for real time monitoring of free-radical polymerization (FRP) of methyl methacrylate (MMA). In situ FRP experiments were performed at various temperatures. Positive activation energy for NADP was measured and found to be 9.2 kcal/mol.

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Contamination Of Roadside Soil, Plants, And Air With Heavy Metals In Jordan, A Comparative Study, Quasem M. Jaradat, Kamal A. Momani Jan 1999

Contamination Of Roadside Soil, Plants, And Air With Heavy Metals In Jordan, A Comparative Study, Quasem M. Jaradat, Kamal A. Momani

Turkish Journal of Chemistry

Copper, lead, cadmium, and zinc levels were analyzed by atomic absorption spectrophotometry in surface soil, plants, and air samples taken from both sides of the major highway connecting Amman with the southern parts of Jordan. Elevated levels of the studied elements were found in both soil and plants on the east side and on the west side of the road compared with the background values. The higher levels of heavy metals east of the road were due to the westerly prevailing wind at the sampling sites. The comtamination decreased exponentially with distance from the edge of the road and dropped …

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Determination Of Patent Blue V And Carmoisine In Gelatine Desserts By Derivative Spectrophotometry, Yüksel Özdemi̇r, Ayşe Arzu Akkan Jan 1999

Determination Of Patent Blue V And Carmoisine In Gelatine Desserts By Derivative Spectrophotometry, Yüksel Özdemi̇r, Ayşe Arzu Akkan

Turkish Journal of Chemistry

A first-derivative spectrophotometric method was developed for quantitative determination of two synthetic organic dyes, Carmoisine and Patent Blue V, which are under governmental regulations all over the world because of their toxicity and carcinogenity. In this study, Carmoisine and Patent Blue V were simultaneously determined in their binary mixtures by first-derivative spectrophotometry. The method was applied to different gelatine desserts. The first-derivative derivative method did not eliminate turbid background in the samples. A simple background correction procedure involving a C_{18}-cartridge sample preparation step was developed for determination of dyes in gelatine dessert by first-derivative spectrophotometry. The C_{18}-cartridge sample preparation step …

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Chlorination Of Two Turkish Lignites In Water And Water-Carbon Tetrachloride Media, Semra Karaca, Yücel Yaşar Kadioğlu, Sami̇h Bayrakçeken, M. Şahi̇n Gülaboğlu Jan 1999

Chlorination Of Two Turkish Lignites In Water And Water-Carbon Tetrachloride Media, Semra Karaca, Yücel Yaşar Kadioğlu, Sami̇h Bayrakçeken, M. Şahi̇n Gülaboğlu

Turkish Journal of Chemistry

The chlorine uptake of two Turkish lignites during chlorinolysis with chlorine gas in water and water-carbon tetrachloride media at ambient pressure (\cong 610 mmHg) was examined. The effects of speed of stirring (5-20s^{-1}), particle size (74-88, 150-180 and 250-425 \mu m), temperature (13-70°C) and chlorination time (0-18000 s) were studied. It is shown that the amount of chlorine uptake of both coals increased with decreasing particle size and increasing temperature.

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Cover And Contents Jan 1999

Cover And Contents

Turkish Journal of Chemistry

No abstract provided.

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Complexation Of Benzoate Ligand With The Divalent D^10 Acceptors At Different Temperatures, Betül Başaran, Efrai̇m Avşar Jan 1999

Complexation Of Benzoate Ligand With The Divalent D^10 Acceptors At Different Temperatures, Betül Başaran, Efrai̇m Avşar

Turkish Journal of Chemistry

The complex formation between zinc(II), cadmium(II), mercury(II) and benzoate ions was studied potentiometrically with glass electrode at different temperatures. The measurements have been performed in a perchlorate medium of the unit ionic strength at 25, 30, 35 and 40°C. The stability constants of the complexes were found in the order of increasing softness i.e. Zn(II) < -Cd(II)

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Stabilities Of Complexes Of Scandium(Iii) And Yttrium(Iii) With Salicylic Acid, Naci̇ye Türkel, Rahmi̇ye Aydin, Ulvi̇ye Özer Jan 1999

Stabilities Of Complexes Of Scandium(Iii) And Yttrium(Iii) With Salicylic Acid, Naci̇ye Türkel, Rahmi̇ye Aydin, Ulvi̇ye Özer

Turkish Journal of Chemistry

The interactions of Sc(III) and Y(III) ions with salicyclic acid, SA (H_2L), were studied in aqueous solution by means of potentiometric and spectroscopic methods. The binding of SA occurs in Y(III):SA system, either in (1:1) or (1:2) mole ratios. The stability constants of the mono protonated complex, YHL^{2+}, and Y(HL)_2^+ type complex were calculated. The coordination of Sc(III) to SA was defined by means of Job's plot and its formation curve. The stability constants of ScL^+ and Sc(HL)L type complexes were determined by analysis of the potentiometric data; the coordination of SA to Sc(III) occurred through carboxylate and phenolic oxygens. …

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Conformational Analysis Of Linear Peptide (Glu^1-Leu^2-Leu^3-Gly^4-Gly^5-Arg^6-Phe^7nh_2 ), Lütfü Demi̇r, Abdulhali̇k Karabulut, Gökhan Budak, Yusuf Şahi̇n, Nagif Sefteroğlu Jan 1999

Conformational Analysis Of Linear Peptide (Glu^1-Leu^2-Leu^3-Gly^4-Gly^5-Arg^6-Phe^7nh_2 ), Lütfü Demi̇r, Abdulhali̇k Karabulut, Gökhan Budak, Yusuf Şahi̇n, Nagif Sefteroğlu

Turkish Journal of Chemistry

Conformational energy-minimization of the Sea Anemone and Sea Pansy neuropeptide Pol-RFamide (Glu^1-Leu^2-Leu^3-Gly^4-Gly^5-Arg^6-Phe^7-NH_2) was carried out by molecular mechanics (MM). The linkage bonds were characterized by the torsion angles \theta, \psi and \omega and the side groups were characterized by the torsion angles \chi_1, \chi_2, \chi_3\ldots The energy-map for each monopeptide of the Pol-RFamide I was drawn in the range of -180° to 180° with increments of 20°. Conformation facilities for monopeptides were determined from these maps. These results were used in the analysis of the dipeptide (Glu^1-Leu^2). Then, the (Glu^1-Leu^2-Leu^3) tripeptide was examined using the calculated results for the dipeptide. …

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^1h Nmr Spectra Of Some Amidrazone Derivatives, Şule Bahçeci̇, Haydar Yüksek, A. Aykut İki̇zler Jan 1999

^1h Nmr Spectra Of Some Amidrazone Derivatives, Şule Bahçeci̇, Haydar Yüksek, A. Aykut İki̇zler

Turkish Journal of Chemistry

Fifteen amidrazone derivatives (six being new compounds) were synthesized and their proton magnetic resonance spectra were recorded in trifluoroacetic acid (TFA). The protonation shifts, related to alkyl groups and observed on comparison of the spectra run in a neutral solvent and TFA, were attributed to an amidinium-type resonance of the resulting cations in the acidic medium.

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Thin Layer Chromatographic Separation And Quantitation Of L-Dopa And L-Tyrosine In Mixtures, Gülendem Günendi̇, Farünni̇sa Pamuk Jan 1999

Thin Layer Chromatographic Separation And Quantitation Of L-Dopa And L-Tyrosine In Mixtures, Gülendem Günendi̇, Farünni̇sa Pamuk

Turkish Journal of Chemistry

A new TLC separation and quantitation method for L-tyrosine and L-Dopa mixtures was developed. The minimum tyrosine and Dopa quantities which can be measured by this technique are 0.7 and 1.5 \mu g respectively. The method may be used to measure the kinetic parameters of polyphenoloxidase as well as to trace the enzyme catalyzed conversion of L-tyrosine into L-Dopa. For a set of 20 measurements the maximum difference between any two measurements of spot areas was found to be 3 mm^2 (4.5\%) for L-Dopa (4 \mu g) and 2mm^2 (5.6\%) for L-tyrosine (1\mu g).

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Spectrophotometric Determination Of Uranium In Waste Water Of Phosphoric Acid And Fertilizer Manufacturing Process, Ahmet Uyanik, Ni̇hat Tinkiliç, M. Odabaşoğlu, Hüseyi̇n Karaca Jan 1999

Spectrophotometric Determination Of Uranium In Waste Water Of Phosphoric Acid And Fertilizer Manufacturing Process, Ahmet Uyanik, Ni̇hat Tinkiliç, M. Odabaşoğlu, Hüseyi̇n Karaca

Turkish Journal of Chemistry

In this study, waste water drains and produced phosphate fertilizers of conventional wet-process (hemihydrate) phosphoric acid and phosphate fertilizer plants were investigated to determine the average uranium contents in the active manufacturing period. The method chosen for the determination of uranium was an extension of an existing spectroanalytical method and was adopted for waste water analysis as described. The results show that average uranium contents (mg m^{-3}) in a three-month period are appreciable in the waste water channel of the H_3PO_4 unit, produce acid containing 28% P_2O_5 (20.75), H_3PO_4 unit, produce acid containing 54% P_2O_5 (35.69), NPK (Nitrogen, Phosphorus, Potassium …

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Supercritical Co_2 Extraction Of Ethanol, A. Güvenç, Ü. Mehmetoğlu, A. Çalimli Jan 1999

Supercritical Co_2 Extraction Of Ethanol, A. Güvenç, Ü. Mehmetoğlu, A. Çalimli

Turkish Journal of Chemistry

Extraction of ethanol was studied from both synthetic ethanol solution and fermentation broth using supercritical CO_2 in an extraction apparatus in ranges of 313 to 333 K and 80 to 160 atmospheres, for varying extraction times. The experimental system consists mainly of four parts: a CO_2 storage system, a high-pressure liquid pump, an extractor and a product collection unit. Samples were analyzed by gas chromatography. Effects of temperature, pressure, extraction time, initial ethanol concentration and consecutive solvent feeding on extraction yield were investigated. It was found that increasing the initial ethanol concentration and extraction pressure and decreasing the extraction temperature …

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Hydrogen Evolution At Platinum (Pt) And At Platinized Platinum (Ptz) Cathodes, Bi̇rgül Yazici Jan 1999

Hydrogen Evolution At Platinum (Pt) And At Platinized Platinum (Ptz) Cathodes, Bi̇rgül Yazici

Turkish Journal of Chemistry

In this study, the cathodic behaviours of bright platinum (Pt) and at platinized platinum (Ptz) on the platinum anode were investigated in a 1M Na_2SO_4 electrolyte (pH, from 2 to 8) by means of electrolysis. The theoretical (\Delta Erev) and experimental (\Delta E_{exp}) discharge potentials and the cathodic overpotentials (\etac) of the systems were determined. The amounts of hydrogen gas produced at different times on the cathodes at a constant potential (5V) were measured and the hydrogen yield was calculated. The resulting scheme has been very helpful to obtain wodified electrocatalytic coating and electrode structures at Ptz cathode, able to …

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Reaction Mechanism And Kinetics Of Aqueous Solutions Of Primary And Secondary Alkanolamines And Carbon Dioxide, Olgac Bavbek, Erdoğan Alper Jan 1999

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.

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