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Articles 2131 - 2160 of 2730
Full-Text Articles in Physical Sciences and Mathematics
Synthesis And Some Reactions Of 4-Benzoyl-5-Phenyl-1-(2,4,6-Trichloro Phenyl)-1h-Pyrazole-3-Carboxylic Acid, Ahmet Şener, İshak Bi̇ldi̇ri̇ci̇
Synthesis And Some Reactions Of 4-Benzoyl-5-Phenyl-1-(2,4,6-Trichloro Phenyl)-1h-Pyrazole-3-Carboxylic Acid, Ahmet Şener, İshak Bi̇ldi̇ri̇ci̇
Turkish Journal of Chemistry
Furandione 1 was reacted with 2,4,6-trichlorophenylhydrazine to give the 1H-pyrazole-3-carboxylic acid 2 together with a new pyridazinone derivative 3. Then 2 was converted into the corresponding ester 5 or amide 6 derivatives, respectively, via reactions of its acid chloride 4 with various alcohols or N-nucleophiles. Nitrile derivative 7 was obtained by dehydration of 6a in a mixture of SOCl_2 and DMF. Condensation reactions of 2 with some hydrazines led to the formation of pyrazolo [3,4-d] pyridazinone 8 derivatives.
Chalcogeno Ureas Derived From Bis(1,3-Diazepan-2-Ylidene), Yetki̇n Gök, Engi̇n Çeti̇nkaya
Chalcogeno Ureas Derived From Bis(1,3-Diazepan-2-Ylidene), Yetki̇n Gök, Engi̇n Çeti̇nkaya
Turkish Journal of Chemistry
A series of new electron rich olefins (=\overset{ } CNR(CH_2)_4\overset{ }NR)_2, 3, (a; R = CH_2C_6H_5, b; R = CH_2C_6H_4-OMe-p, c; R = CH_2C_6H_4-NMe_2-p) was generated via the condensation of RNH(CH_2)_4NHR with Me_2NCH (OMe)_2. The C=C bond cleavage reactions of 3 with S_8 and Se provide a simple and straightforward method for the synthesis of 1,3-diazepan-2-chalcogenones 4 and 5, respectively.
Mechanical And Light Transmittance Properties Of Locust Bean Gum Based Edible Films, Meltem Aydinli, Mehmet Tutaş, Ö. Altan Bozdemi̇r
Mechanical And Light Transmittance Properties Of Locust Bean Gum Based Edible Films, Meltem Aydinli, Mehmet Tutaş, Ö. Altan Bozdemi̇r
Turkish Journal of Chemistry
The behavior of locust bean gum (LBG) under heat was investigated by thermogravimetric (TG), differential thermogravimetric (DTG) and differential scanning calorimetric (DSC) methods. It was observed from the TG, DTG and DSC curves that LBG does not melt and is stable up to 300 °C, although exothermic degradation occurs at higher temperatures. The effect of the amount and molecular weight of polyethylene glycol (PEG) on the light transmittance and mechanical properties of these edible films was also examined. Haze increased and the luminous transmittance and total light transmittance values decreased with both the quantity and molecular weight of PEG. On …
The Synthesis Of Substituted 4,4'-Thiobis(Aminophenylglyoxime) And Their Polymeric Metal Complexes With Cu(Ii), Ni(Ii) And Co(Ii) Salts, Ahmet Coşkun, İbrahi̇m Karataş
The Synthesis Of Substituted 4,4'-Thiobis(Aminophenylglyoxime) And Their Polymeric Metal Complexes With Cu(Ii), Ni(Ii) And Co(Ii) Salts, Ahmet Coşkun, İbrahi̇m Karataş
Turkish Journal of Chemistry
4,4'-Bis(chloroacetyl)diphenyl thioether (HL) was synthesized from chloroacetyl chloride and diphenyl thioether in the presence of AlCl_3 as catalyst in a Friedel-Crafts reaction. Subsequently, its keto oxime (H_2L) and glyoxime (H_4L) derivatives were also prepared. Then 3 new substituted 4,4'-thiobis(aminophen- ylglyoxime) (H_4L^{1 - 3}) were synthesized from 4,4'-thiobis(chlorophenylglyoxime) and the corresponding amines. The Ni(II), Cu(II) and Co(II) complexes of these ligands were prepared. The structures of these ligands and their complexes were identifed by FT-IR, ^1H NMR and ICP-AES spectral data, elemental analyses and magnetic measurements.
Determination Of Trace Amounts Of Iodide By An Inhibition Kinetic Spectrophotometric Method, Ramazan Gürkan, Ni̇lgün Bi̇çer, M. Hi̇kmet Özkan, Mehmet Akçay
Determination Of Trace Amounts Of Iodide By An Inhibition Kinetic Spectrophotometric Method, Ramazan Gürkan, Ni̇lgün Bi̇çer, M. Hi̇kmet Özkan, Mehmet Akçay
Turkish Journal of Chemistry
In this study, the reaction between Co(III)-EDTA and hypophosphite ion, catalyzed by Pd(II), was chosen as the indicator reaction. The inhibition kinetics of this catalytic reaction were investigated in the presence of iodide ion and the possibility of its analytical application was evaluated. Catalyzers other than PdCl_2 (Pt, Au and Ni salts) were assayed for the indicator reaction and it was observed that these catalysts have no effect on the reaction. The important variables that affected the reaction rate were investigated and the optimum conditions giving maximum sensitivity were established. The calibration graph, prepared following the inhibition kinetic method, gave …
Sorption Preconcentration And Determination Of Molybdenum(Vi) By Diffuse Reflection Spectroscopy, Olga N. Kononova, Sergey V. Kachin, Anastasiya E. Chaikovskaya, Alexander G. Kholmogorov, Olga P. Kalyaki̇na
Sorption Preconcentration And Determination Of Molybdenum(Vi) By Diffuse Reflection Spectroscopy, Olga N. Kononova, Sergey V. Kachin, Anastasiya E. Chaikovskaya, Alexander G. Kholmogorov, Olga P. Kalyaki̇na
Turkish Journal of Chemistry
The present work focuses on the preconcentration of molybdenum and its determination in aqueous solutions by means of diffuse reflection spectroscopy. The preconcentration of Mo(VI) was carried out using the macroporous strong basic anion exchanger AV-17-10P synthesized on the basis of styrene and divinylbenzene. The method for Mo determination with this collector in industrial solutions and natural water was developed using solid-phase spectroscopy. The colored surface compound to be determined was obtained by a preceding Mo(VI) sorption on the resin and by subsequent treatment of the concentrate obtained with definite amounts of pyrocatechol violet. The calibration curve is linear at …
Determination Of Fluoride In Various Samples And Some Infusions Using A Fluoride Selective Electrode, Şeri̇fe Tokalioğlu, Şenol Kartal, Uğur Şahi̇n
Determination Of Fluoride In Various Samples And Some Infusions Using A Fluoride Selective Electrode, Şeri̇fe Tokalioğlu, Şenol Kartal, Uğur Şahi̇n
Turkish Journal of Chemistry
The determination of fluoride in some environmental samples was performed using a fluoride ion-selective electrode. Fluoride concentrations were determined in drinking waters (from different provinces, districts and villages in Turkey), fruit juices, bottled water samples, toothpastes and tooth powders, liquors of Turkish coffee, coffee, linden, rose hip, and various brand tea infusions, and dust samples collected from the Erciyes University campus car park. The average fluoride concentration in 39 drinking waters was 0.21 mg L^{-1} (0.02--1.42 mg L^{-1}); the level of dissolved fluoride in the dust samples was 1.39 \pm 0.09 \mu g g^{-1}; the fluoride concentrations in liquors taken …
The Effect Of Cultural Conditions On The Variations Of Sod, Cat And Gsh-Px Activities And Lpo Levels In The Filamentous Fungus Fusarium Equiseti, Hülya Ayar Kayali, Leman Tarhan
The Effect Of Cultural Conditions On The Variations Of Sod, Cat And Gsh-Px Activities And Lpo Levels In The Filamentous Fungus Fusarium Equiseti, Hülya Ayar Kayali, Leman Tarhan
Turkish Journal of Chemistry
The changes in the activity of cellular detoxifying defence enzymes such as SOD, CAT and GSH-Px against superoxide anion radical and hydrogen peroxide, and in LPO levels in the filamentous fungus, Fusarium equiseti were measured under growth condition. Experiments were performed comparing changes in glycerol and saccharose (5-25 g/L) as carbon sources, and in glycine, peptone (5-35 g/L) as nitrogen sources in an AFM medium. While SOD activities correlate well with respect to the increase in the glycerol concentration (r = 0.437, p < 0.001), CAT activities showed negative correlation (r = -0.663, p < 0.001). The increase in SOD and CAT activities of F. equiseti correlated with increases in saccharose concentration. When glycerol and saccharose were used as carbon sources, the maximum SOD, CAT and GSH-Px enzymes activities and the minimum LPO level were determined in the medium containing 15 g/L of saccharose on the 12^{th} day at 66.61, 182.79, 1.045 IU/mg and 1.41 nmol MDA/ gr wet weight, respectively. The effects of peptone and glycine as nitrogen sources were also investigated: 53.4% and 48.03% decreases were observed in the SOD and CAT activities of F. equiseti in the presence of 10 g/L of peptone in the culture medium. The presence of 15 g/L of glycine caused 5.30% and 69.90% decreases in the SOD and CAT activities in comparison to the presence of 15 g/L of saccharose, respectively. On the other hand, LPO levels increased in proportion to the decrease in antioxidant enzyme activities in glycine and peptone supplemented media.
3-Hydroxy Fatty Acids From The Flowers Of Hypericum Lysimachioides Var. Lysimachioides, Hasan Çeti̇n Özen, Mehmet Başhan, Zuhal Toker, Cumali̇ Keski̇n
3-Hydroxy Fatty Acids From The Flowers Of Hypericum Lysimachioides Var. Lysimachioides, Hasan Çeti̇n Özen, Mehmet Başhan, Zuhal Toker, Cumali̇ Keski̇n
Turkish Journal of Chemistry
Fatty acid methyl esters in the leaves and flowers of Hypericum lysimachioides var. lysimachioides (Guttiferae) were analyzed by gas chromatography and gas chromatography-mass spectrometry. The flowers of H. lysimachioides var. lysimachioides produced unusual 3-hydroxy fatty acids [3-hydroxy- tetradecanoic acid (3-OH-C14:0) and 3-hydroxy-octadecanoic acid (3-OH-C18:0)], along with other normal fatty acids. Major components were linolenic and palmitic acids for both leaves and flowers.
Synthesis, Characterization Of Some Co(Iii) Complexes With Vic-Dioxime Ligands And Their Antimicrobial Properties, Erdal Canpolat, Mehmet Kaya, Seher Gür
Synthesis, Characterization Of Some Co(Iii) Complexes With Vic-Dioxime Ligands And Their Antimicrobial Properties, Erdal Canpolat, Mehmet Kaya, Seher Gür
Turkish Journal of Chemistry
In this study, 6 different new vic-dioxime ligands and their mononuclear complexes with Co(III) have been synthesized. The structures of these compounds were identified by using elemental analyses, IR, ^{1}H and ^{13}C NMR, electronic spectra, magnetic susceptibility measurements and conductivity. In addition, the thermal characterizations and antimicrobial activities of the ligands and their complexes have been investigated.
Flame Atomic Absorption Spectrometric Determination Of Manganese In Alloys After Preconcentration Onto Amberlite Xad-4 Loaded With Saccharomyces Carlsbergensis, Sitki Baytak, A. Rehber Türker
Flame Atomic Absorption Spectrometric Determination Of Manganese In Alloys After Preconcentration Onto Amberlite Xad-4 Loaded With Saccharomyces Carlsbergensis, Sitki Baytak, A. Rehber Türker
Turkish Journal of Chemistry
A sensitive and simple enrichment method using microorganisms as an adsorbent is described for the determination of trace manganese in alloys. Manganese was determined by flame atomic absorption spectrometry after preconcentration onto Amberlite XAD-4 loaded with Saccharomyces carlsbergensis. The optimum values of pH, amount of adsorbent, amount of microorganism, eluent type and volume of sample solution were determined for the quantitative recovery (>95%) of manganese. Results have been compared with those obtained without using microorganisms. Under optimum conditions, recoveries were 98 \pm 3% with microorganisms and 68 \pm 2% without microorganisms for manganese at a 95% confidence level. The …
Crystal Habit Modification Of Vitamin C (L-Ascorbic Acid) Due To Solvent Effects, Ali̇ Arslantaş, Walter C. Ermler, Rahmi̇ Yazici, Di̇lhan M. Kalyon
Crystal Habit Modification Of Vitamin C (L-Ascorbic Acid) Due To Solvent Effects, Ali̇ Arslantaş, Walter C. Ermler, Rahmi̇ Yazici, Di̇lhan M. Kalyon
Turkish Journal of Chemistry
Crystal morphologies are predicted for vitamin C (L-ascorbic acid) using attachment energy methods. The significant differences between predicted and observed morphologies when vitamin C is grown from water, isopropyl alcohol, acetone-water solution, and isopropyl alcohol-methanol solution are attributed to the effect of solvent on the growth rate of the various crystal habit faces. This effect, particularly the role of hydrogen bonding between solvent and crystal surface, is examined. Molecular modeling is combined with the results of simple experiments charting the habit shift of vitamin C as a function of the hydrogen bonding tendency of the solvent or solvent mixture. Attachment …
Synthesis And Some Reactions Of 4-Benzoyl-5-Phenyl-1-Pyridin-2-Yl-1h- Pyrazole-3-Carboxylic Acid, Ahmet Şener, Esvet Akbaş, M. Kasim Şener
Synthesis And Some Reactions Of 4-Benzoyl-5-Phenyl-1-Pyridin-2-Yl-1h- Pyrazole-3-Carboxylic Acid, Ahmet Şener, Esvet Akbaş, M. Kasim Şener
Turkish Journal of Chemistry
The 1H-pyrazole-3-carboxylic acid 2, obtained from the furandione 1 and 2-hydrazinopyridine, was decarboxylated to give 4-benzoyl-5-phenyl-1-pyridin-2-yl-pyrazole derivative 3. Some ester 4 derivatives of 2 were prepared by the Fischer esterification reactions of 2 with various alcohols. Cyclocondensation reactions of 2 with phenyl hydrazine or hydrazine hydrate led to the formation of derivatives of pyrazolo[3,4-d]pyridazine 5 derivatives.
Chemically Crosslinked N-Vinyl-2-Pyrrolidone/2-Hydroxyethyl Methacrylate (Vp/Hema) Copolymer For The Controlled Release Of Cyclic Oligopeptide, Bashir Ahmad, Shumaila Bashir, Shams-Un Nisa, M. B. Huglin
Chemically Crosslinked N-Vinyl-2-Pyrrolidone/2-Hydroxyethyl Methacrylate (Vp/Hema) Copolymer For The Controlled Release Of Cyclic Oligopeptide, Bashir Ahmad, Shumaila Bashir, Shams-Un Nisa, M. B. Huglin
Turkish Journal of Chemistry
Crosslinked copolymers of various compositions of N-vinyl-2-pyrrolidone (VP) and 2-hydroxyethyl methacrylate (HEMA) were prepared chemically in the presence of a crosslinking agent. The swelling mechanism was non-Fickian with about 86% conversion of feed composition to crosslinked copolymer. The reactivity ratios r_1 = 0.045 and r_2 = 3.07 for VP and HEMA indicate that HEMA is more reactive than VP in the reaction. Hydrophilicity, hydrophobicity and monomer composition in the copolymer controlled the drug release from the hydrogels.
Anodic Stripping Voltammetric Determination Of Gold On A Polyvinylferrocene Coated Glassy Carbon Electrode, Muammer Kavanoz, Handan Gülce, Atti̇la Yildiz
Anodic Stripping Voltammetric Determination Of Gold On A Polyvinylferrocene Coated Glassy Carbon Electrode, Muammer Kavanoz, Handan Gülce, Atti̇la Yildiz
Turkish Journal of Chemistry
The anodic stripping voltammetric determination of gold was accomplished on a chemically modified glassy carbon electrode in a solution containing chloride ions. A modifying polymer, polyvinylferrocene, was coated by immersing the glassy carbon surface in its solution in methylene chloride followed by solvent evaporation. Tetrahalo complexes of gold, tetrachloroaurate(III) and tetrabromoaurate(III) ions, were found to be reduced to metallic gold by chemical reduction during immersion of the polymer coated electrode into the solution containing aurate(III) ions. This reaction was utilized as means of preconcentration without the need for cathodic electrolysis prior to the anodic stripping of metallic gold. The effects …
Determination Of Selenium(Iv) Using O-Phenylenediamine By Differential Pulse Polarography/Interference Of Metal Ions, Recai̇ İnam, Çi̇ğdem Toprak
Determination Of Selenium(Iv) Using O-Phenylenediamine By Differential Pulse Polarography/Interference Of Metal Ions, Recai̇ İnam, Çi̇ğdem Toprak
Turkish Journal of Chemistry
A new sensitive and selective pulse polarographic method for the determination of Se(IV) next to interfering ions is described. This method is based on the highly sensitive peak formed by the reaction of Se(IV) with o-phenylenediamine in Britton-Robinson buffer solution (pH 2.5) at --0.08 V vs. SCE. The new peak due to the Se(IV)/o-PDA complex not only prevents the interference of Pb(II), Cd(II) and Sn(II) for selenium, but also increases its sensitivity. A linear calibration graph is obtained for Se(IV) at a concentration of 5.0 x 10^{-8} to 6.8 x 10^{-5} M with a correlation coefficient of 0.9988. The proposed …
A Convenient Synthesis Of 3,6-Disubstituted-1,4-Dihydro-[1,2,4,5]Tetrazines And Preparation Of New Acetic Acid Derivatives Containing 5-Oxo-4-Phenylamino- 4,5-Dihydro-[1,2,4]Triazole, Ahmet Demi̇rbaş
Turkish Journal of Chemistry
A series of compounds 8a-e, was synthesized by condensation of compounds 7a-e with ethyl bromoacetate. The treatment of compounds 8a-e with hydrazine hydrate afforded the corresponding hydrazide derivatives (9a-e). Subsequently, compounds 9a-e were converted to alkylidene hydrazides (10a-e). Moreover, upon heating in the presence of carboxylic acids, compounds 9a-e unexpectedly gave 1,4-dihydro-[1,2,4,5]tetrazine derivatives (11a-e).
A Rapid Spectrophotometric Method To Resolve A Binary Mixture Of Food Colorants (Riboflavine And Sunset Yellow), Mahmure Üstün Özgür
A Rapid Spectrophotometric Method To Resolve A Binary Mixture Of Food Colorants (Riboflavine And Sunset Yellow), Mahmure Üstün Özgür
Turkish Journal of Chemistry
A very simple and rapid spectrophotometric method using measurements at zero-crossing wavelength is described for resolving binary mixtures of riboflavine (E-101) and sunset yellow (E-110) in a powder drink. The assay procedure for E-110 and E-101 involves the extraction of the colorants from the powder drink with pH 4.5 acetate buffer, filtration, appropriate dilution, and measurement of the first derivative absorbance values (denoted as ^1D). Calibration graphs are linear up to 25.0 \mu g.mL^{-1} for E-101 and 40.0 \mu g.mL^{-1} for E-110. The sensitivity and reproducibility of the method were determined by using the synthetic mixtures in different ratios prepared …
A Sensitive Spectrophotometric Assay For Tinidazole And Metronidazole Using A Pd-C And Formic Acid Reduction System, Nandipura Dyavegowda Dinesh, Padmarajaiah Nagaraja, K. Subbegowda Rangappa
A Sensitive Spectrophotometric Assay For Tinidazole And Metronidazole Using A Pd-C And Formic Acid Reduction System, Nandipura Dyavegowda Dinesh, Padmarajaiah Nagaraja, K. Subbegowda Rangappa
Turkish Journal of Chemistry
A simple, sensitive and rapid spectrophotometric method for the determination of tinidazole (TZ) and metronidazole (MZ) in pure as well as in dosage form is described. The method is based on the reduction of the nitro group of drugs using a novel and versatile reduction system comprising 10% Pd-C and formic acid. The resulting amine was then subjected to a condensation reaction with sodium 1,2-naphthaquinone-4-sulfonate (NQS) to form red Schiff base with an absorption maximum at 510 nm. Beer's law was obeyed in the concentration ranges 2.0 to 45.0 \mu g mL^{-1} and 1.5 to 37.0 \mu g mL^{-1} with …
Facile Synthesis Of Hydantoin Derivatives Under Microwave Irradiation, Khalil Faghihi, Khosrow Zamani, Akbar Mobinikhaledi
Facile Synthesis Of Hydantoin Derivatives Under Microwave Irradiation, Khalil Faghihi, Khosrow Zamani, Akbar Mobinikhaledi
Turkish Journal of Chemistry
The rapid and highly efficient synthesis of hydantoin derivatives 3(a-f) was achieved under microwave irradiation by using a domestic microwave oven from the reactions of cyanohydrin derivatives 2(a-f) with ammonium carbonate. The reaction proceeded rapidly (2-5 min.), and as a result a series of hydantoin derivatives 3(a-f) were obtained in high yields. All of the synthesized compounds were fully characterized by their melting point, ^1H-NMR, FTIR spectroscopy and elemental analyses. Cyanohydrin derivatives 2(a-f) were also prepared from the ketone derivatives 1(a-f) with potassium cyanide in the presence of sodium metabisulfite in an additional reaction.
The Kinetics Of The Photochemical Reaction Of Methylene Green With Methylamine And Ethylamine, Rehana Saeed, Fahim Uddin, Zahida Khalid
The Kinetics Of The Photochemical Reaction Of Methylene Green With Methylamine And Ethylamine, Rehana Saeed, Fahim Uddin, Zahida Khalid
Turkish Journal of Chemistry
The photochemical reduction of methylene green with methylamine and ethylamine in 50% aqueous isopropanol was studied. The photochemical reduction was carried out in a special type of optical processor associated with a deoxygenating system, a temperature controlling unit and a magnetic stirring system. A monochromatic light of 657 nm wavelength was used for irradiation of oxygen free reaction solutions in a double walled reaction cell. The transmitted light was measured and recorded in terms of electrical signals with the help of a calibrated galvanometer. Acidities of the solutions were measured with the help of a spectrophotometer based on the Hammet …
Electrocatalytic Determination Of Ascorbic Acid Using Glassy Carbon Modified With Nickel(Ii) Macrocycle Containing Dianionic Tetraazaannulene Ligand, Mozhgan Khorasai-Motlagh, Meissam Noroozifar
Electrocatalytic Determination Of Ascorbic Acid Using Glassy Carbon Modified With Nickel(Ii) Macrocycle Containing Dianionic Tetraazaannulene Ligand, Mozhgan Khorasai-Motlagh, Meissam Noroozifar
Turkish Journal of Chemistry
A symmetric Ni(II) tetraaza macrocycle modified glassy electrode shows electrocatalytic activity for the oxidation of L-ascorbic acid at pH 7. It was shown the peak potential shifted to the negative by 250 mV compared with that for the bare electrode in the cyclic voltammograms. The calibration curve was linear up to 5 mM with a detection limit of 2.5 \times 10^{-4} mM and RSD% better than 2.8%. Excipients used as additives in pharmaceutical formulations and foods did not interfere in the proposed procedure. This new modified electrode was applied to commercial pharmaceutical tablets, injections and foods. The obtained results were …
Formation Of The Monolithic Silica Gel Column With Bimodal Pore Structure, Wenhui Gao, Gegliang Yang, Jing Yang, Haiyan Liu
Formation Of The Monolithic Silica Gel Column With Bimodal Pore Structure, Wenhui Gao, Gegliang Yang, Jing Yang, Haiyan Liu
Turkish Journal of Chemistry
A biporous monolithic silica gel column possessing both micrometer sized through-pores and nanometer sized mesopores located in the silica skeletons was prepared and the high concentration porogen (e.g., 2 mol/L ammonium hydroxide solution) was use for increasing mesopore size in this work. The mechanism for the preparation of the monolithic column was investigated in detail. Moreover, the effect of the polyethylene glycol concentration in the starting solution was studied and it was found that a lower concentration range was also suitable for forming the interconnected porous structure for the monolithic silica gel column. At lower concentrations, however, the phase separation …
Anionic Polymerization Of Methyl Methacrylate As Promoted By A N-Butyl Lithium-Pyridazine-Polyether Alkoxide Based Complex Initiator System, Z. Tim Hamaudi, Ni̇han Nugay, Turgut Nugay
Anionic Polymerization Of Methyl Methacrylate As Promoted By A N-Butyl Lithium-Pyridazine-Polyether Alkoxide Based Complex Initiator System, Z. Tim Hamaudi, Ni̇han Nugay, Turgut Nugay
Turkish Journal of Chemistry
Polymerization of methyl methacrylate was conducted using a n-butyl lithium/pyridazine system as initiator in tetrahydrofuran (THF) and toluene. Special attention was focused on using some lithium polyether alkoxides as polymerization is promoted at ambient temperatures. The positive effects of these \mu /\sigma -type ligands such as lithium 2-(2-methoxyethoxy)ethoxide and lithium 2-(methoxy)ethoxide on controlling the living character, molecular weight, stereoregularity and yield of the produced polymers were all demonstrated. It was found that initiator/lithium-2-(methoxy)ethoxide in a 1/10 ratio gives the most controlled polymerization. All products were then characterized by size exclusion chromatography (SEC), proton nuclear magnetic resonance (^1H NMR) and differential …
An Efficient Synthesis Of Substituted 4-Aryl-3-Cyano-2-Amino Thiophenes By A Stepwise Gewald Reaction, Ferhan Tümer, Duygu Eki̇nci̇, Kani̇ Zi̇lbeyaz, Ümi̇t Demi̇r
An Efficient Synthesis Of Substituted 4-Aryl-3-Cyano-2-Amino Thiophenes By A Stepwise Gewald Reaction, Ferhan Tümer, Duygu Eki̇nci̇, Kani̇ Zi̇lbeyaz, Ümi̇t Demi̇r
Turkish Journal of Chemistry
The title compounds were efficiently synthesised starting from aryl methyl ketones in 3 steps. Knoevenagel condensation of aryl methyl ketones with malononitrile gave the corresponding crotonitriles (5a-f). Methyl groups of the crotonitriles (5a-f) were then efficiently brominated by refluxing and lightening the reaction media to give bromocrotonitriles (6a-f). The bromocrotonitriles (6a-f) were finally cyclised by treatment with NaSH to give the title compounds.
Synthesis, Magneto-Spectral And Thermal Characteristics Of Some 7-Coordinated Compounds Of Lanthanides(Iii) Chlorides With 4[(Furan-2-Ylmethylene)Amino]-1,5-Dimethyl-2-Phenyl Pyrazol-3-One And Isonicotinic Acid(3',4',5'-Trimethoxybenzylidene)Hydrazide, Ram K. Agarwal, Surendra Prasad, Neetu Goel
Synthesis, Magneto-Spectral And Thermal Characteristics Of Some 7-Coordinated Compounds Of Lanthanides(Iii) Chlorides With 4[(Furan-2-Ylmethylene)Amino]-1,5-Dimethyl-2-Phenyl Pyrazol-3-One And Isonicotinic Acid(3',4',5'-Trimethoxybenzylidene)Hydrazide, Ram K. Agarwal, Surendra Prasad, Neetu Goel
Turkish Journal of Chemistry
In the present work, we describe the isolation of some lanthanide(III) chlorides coordination compounds with 4[(furan-2-ylmethylene)amino]-1,5-dimethyl-2-phenyl pyrazol-3-one (FDPPO) and isonicotinic acid(3',4',5'-trimethoxybenzylidene)hydrazide (ITMBH) with the general composition [Ln(L)_2Cl_3] (Ln = La, Pr, Nd, Sm, Gd, Tb, Dy or Ho; L = FDPPO or ITMBH). All the isolated compounds were characterized through various physico-chemical studies. The coordinating ligands FDPPO or ITMBH act as neutral bidentate N and O-donors in the present compounds. The central metal ion displays the coordination number 7 in these complexes. Thermal stabilities of these complexes were also studied through thermogravimetric analysis.
Photophysical Properties And Electrochemistry Of The N,N'-Bis-N-Butyl Derivative Of Naphthalene Diimide, Yevgen Posokhov, Serap Alp, Banu Köz, Yusuf Di̇lgi̇n, Siddik İçli̇
Photophysical Properties And Electrochemistry Of The N,N'-Bis-N-Butyl Derivative Of Naphthalene Diimide, Yevgen Posokhov, Serap Alp, Banu Köz, Yusuf Di̇lgi̇n, Siddik İçli̇
Turkish Journal of Chemistry
The spectral-luminescent properties and electrochemistry of the N,N'-bis-n-butyl derivative of naphthalene diimide were studied. The main photophysical parameters (quantum yield, rate constants of fluorescence and of non-radiative deactivation and fluorescence lifetime) were determined. The LUMO value (-3.51 eV) was determined by cyclic voltammetry. The N,N'-bis-n-butyl derivative of naphthalene diimide (BBND) shows 2 reversible reduction steps (-1.19 V and -1.75 V vs. Ferrocene) in chloroform. Quenching the fluorescence emissions of aromatic donor molecules in acetonitrile revealed the electron acceptor ability of the studied naphthalene diimide derivative. It has been found that, in contrast to perylene diimide derivatives, which form \pi-electron donor-acceptor …
Diffusion Effect On The Anodic Reactions Of Tungsten, Mustafa Anik, Tuba Cansizoğlu, Si̇nem Çevi̇k
Diffusion Effect On The Anodic Reactions Of Tungsten, Mustafa Anik, Tuba Cansizoğlu, Si̇nem Çevi̇k
Turkish Journal of Chemistry
Potentiodynamic and potentiostatic polarizations, and a rotating disk electrode technique were used to study the influence of diffusion on the anodic reactions of tungsten (W) in a broad pH range (\sim 0.3--13.5) in H_3PO_4 buffered solutions. The anodic current was controlled totally by the kinetics of H^+ -assisted dissolution below pH 1 (Region A). At around pH 2.5 (Region B), in addition to the kinetics of H_2O-assisted dissolution, specimen rotation had an effect on the current. This observation was attributed mainly to the physical damage to an oxide phase by hydrodynamic effects and partly to the diffusion of surface H_2WO_4(aq) …
Synthesis And Microbiological Activity Of Some Substituted N-(2-Hydroxy-4-Nitrophenyl)Benzamides And Phenylacetamides As Possible Metabolites Of Antimicrobial Active Benzoxazoles, İlkay Yildiz Ören, Esi̇n Aki Şener, Cengi̇z Ertaş, Özlem Temi̇z Arpaci, İsmai̇l Yalçin, Nurten Altanlar
Synthesis And Microbiological Activity Of Some Substituted N-(2-Hydroxy-4-Nitrophenyl)Benzamides And Phenylacetamides As Possible Metabolites Of Antimicrobial Active Benzoxazoles, İlkay Yildiz Ören, Esi̇n Aki Şener, Cengi̇z Ertaş, Özlem Temi̇z Arpaci, İsmai̇l Yalçin, Nurten Altanlar
Turkish Journal of Chemistry
Some new antimicrobial active N-(2-hydroxy-4-nitrophenyl)- p-substituted benzamide and phenylacetamide analogues (I-II) were prepared by 2-step procedures from the corresponding carboxylic acids as possible metabolites of benzoxazoles. Their antimicrobial activities were tested against 3 Gram-positive and 2 Gram-negative bacteria with the fungus Candida albicans and were also compared with several control drugs. The compounds Ia, Id, IIa, and IIe were active at a MIC value of 12.5 \mu g/mL against the Gram-positive microorganism Bacillus subtilis. Most of the compounds exhibited antifungal activity at a MIC value of 12.5 \mu g/mL against C. albicans. On the other hand, the antimicrobial activity of …
Naphthoquinones From The Roots Of Onosma Argentatum Hub.-Mor. (Boraginaceae), Ufuk Özgen, Maksut Coşkun, Cavi̇t Kazaz, Hasan Seçen
Naphthoquinones From The Roots Of Onosma Argentatum Hub.-Mor. (Boraginaceae), Ufuk Özgen, Maksut Coşkun, Cavi̇t Kazaz, Hasan Seçen
Turkish Journal of Chemistry
Onosma argentatum Hub.-Mor. is an endemic species growing in Turkey. In this study, the roots of O. argentatum were extracted with n-hexane-dichloromethane (1:1). The extract was separated on a silica gel column eluting with n-hexane-ethyl acetate by gradient elution. New naphthoquinone compounds (3 known and 1 new) were isolated and their structures were elucidated by spectroscopic methods as deoxyshikonin, acetyl shikonin, 3-hydroxy-isovaleryl shikonin, and 5,8-O-dimethyl acetyl shikonin.