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Articles 2281 - 2310 of 2730
Full-Text Articles in Physical Sciences and Mathematics
Synthesis, Characterization And Biological Applications Of Organotin(Iv) Derivatives Of 2-(2-Fluoro-4-Biphenyl)Propanoic Acid, Sohail Mahmood, Saqib Ali, Moazzam Hussain Bhatti, Mohammad Mazhar, Rashid Iqbal, Khalid Mohammed Khan, Ghulam Mustafa Maharvi
Synthesis, Characterization And Biological Applications Of Organotin(Iv) Derivatives Of 2-(2-Fluoro-4-Biphenyl)Propanoic Acid, Sohail Mahmood, Saqib Ali, Moazzam Hussain Bhatti, Mohammad Mazhar, Rashid Iqbal, Khalid Mohammed Khan, Ghulam Mustafa Maharvi
Turkish Journal of Chemistry
A series of organotin(IV) derivatives with the general formula R_{4 - n}SnL_{n} (where n = 1 or 2, R = Me, Et, n-Bu, Ph and L = 2-(2-fluoro-4-biphenyl)propanoate) have been synthesized and characterized by infrared, multinuclear NMR (^{1}H, ^{13}C, ^{119}Sn), ^{119m}Sn Mössbauer spectroscopy and mass spectrometry. Screening tests of these compounds showed that they are highly active against various bacteria and fungi.
Changes In Chlorophyll-Carotenoid Contents, Antioxidant Enzyme Activities And Lipid Peroxidation Levels In Zn-Stressed Mentha Pulegium, Ni̇lgün Candan, Leman Tarhan
Changes In Chlorophyll-Carotenoid Contents, Antioxidant Enzyme Activities And Lipid Peroxidation Levels In Zn-Stressed Mentha Pulegium, Ni̇lgün Candan, Leman Tarhan
Turkish Journal of Chemistry
The relationships between chlorophyll-carotenoid contents, the antioxidant enzyme activities, such as superoxide dismutase (SOD), catalase (CAT), ascorbate-dependent peroxidase (AsA-dep POD) and guaiacol-dependent peroxidase (Gua-dep POD), and lipid peroxidation (LPO) levels were investigated in leaves at different positions of M. pulegium grown in nutrient medium containing 0-1 \mu M Zn. The maximum chlorophyll-carotenoid content's SOD and CAT activities and the minimum LPO level were observed in leaf 6 at 7.6 10^{-2} \mu M Zn (as control). While chlorophyll-carotenoid contents in the absence of Zn were lower than those of the control, SOD and CAT activities significantly increased with decreasing Zn concentration. …
Determination Of H_{2}O_{2} Content Of Various Water Samples Using A Chemiluminescence Technique, Tuğba Tüğsüz, Elmas Gök, Serdar Ateş
Determination Of H_{2}O_{2} Content Of Various Water Samples Using A Chemiluminescence Technique, Tuğba Tüğsüz, Elmas Gök, Serdar Ateş
Turkish Journal of Chemistry
Hydrogen peroxide (H_{2}O_{2}) plays an important role in natural water samples. In this study H_{2}O_{2} concentrations were quantified in different water samples by chemiluminescence detection. This method was chosen because of its high sensitivity and suitability for determining low concentrations of H_{2}O_{2}. H_{2}O_{2} is introduced to the oxidation reaction of alkaline luminol solutions in the presence of Co^{2 + } ion catalyst. When these components are mixed, blue light (\lambda = 440 nm) is emitted. Maximum chemiluminescence intensity occurs within 2 s after mixing and is continuous for up to a few minutes, permitting accurate measurements at selected delay times. …
Iridoid, Phenylethanoid And Monoterpene Glycosides From Phlomis Sieheana, Tayfun Ersöz, Ü. Şebnem Harput, İhsan Çaliş, Ali̇ Arslan Dönmez
Iridoid, Phenylethanoid And Monoterpene Glycosides From Phlomis Sieheana, Tayfun Ersöz, Ü. Şebnem Harput, İhsan Çaliş, Ali̇ Arslan Dönmez
Turkish Journal of Chemistry
From the aerial parts of Phlomis sieheana, an iridoid glucoside, ipolamiide (1), six phenylethanoid glycosides, acteoside (= verbascoside) (2), cis-acteoside (3), \beta-hydroxyacteoside (4), leucosceptoside A (5), martynoside (6), forsythoside B (7), and a monoterpene glycoside, betulalbuside A (8) were isolated and characterized. The structure elucidations of the isolated compounds were established on the basis of spectroscopic evidence.
Kinetic Spectrophotometric Determination Of Nanogram Levels Of Manganese (Ii) By Azo Dye -- Potassium Periodate -- 1,10-Phenanthroline System, Konstantin L. Mutaftchiev
Kinetic Spectrophotometric Determination Of Nanogram Levels Of Manganese (Ii) By Azo Dye -- Potassium Periodate -- 1,10-Phenanthroline System, Konstantin L. Mutaftchiev
Turkish Journal of Chemistry
The catalytic effect of manganese (II) on the oxidation of 3 - Methyl - 6 - (2 - hydroxyethoxy) - 2 - [2 - methoxy - 4 - N (N,N - diethylamino) phenylazo] benzothiazolium methylsulphate (MHMDPBM), with potassium periodate in the presence of 1,10-phenanthroline in weakly acidic media was studied. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance of the dye at 560 nm. Under the optimum conditions (4x10^{- 5} mol dm^{- 3} MHMDPBM, 4x10^{- 4} mol dm^{- 3} potassium periodate, 1x10^{- 4} mol dm^{- 3} 1,10-phenanthroline, 0.1 mol dm^{- 3} buffer -- pH 3.0, 70^oC, …
Determination Of Trace Amounts Of Gold(Iii) Using Ethopropazine Hydrochloride And Isothipendyl Hydrochloride: A Spectrophotometric Study, Mahaveer B. Melwanki, Saraswati̇ P. Masti, Jaldappa Seetharamappa
Determination Of Trace Amounts Of Gold(Iii) Using Ethopropazine Hydrochloride And Isothipendyl Hydrochloride: A Spectrophotometric Study, Mahaveer B. Melwanki, Saraswati̇ P. Masti, Jaldappa Seetharamappa
Turkish Journal of Chemistry
Two simple, sensitive and accurate spectrophotometric methods have been proposed for the determination of micro amounts of gold (III) using ethopropazine hydrochloride (EPH) and isothipendyl hydrochloride (IPH). The methods are based on the oxidation of phenothiazines by gold (III) to give red radical cations having maximum absorption at 513 and at 512 nm with molar absorptivities of 2.0 X 10^{4} and 2.1 X 10^{4} l mol^{ - 1} cm^{ - 1} for EPH and IPH respectively. Beer's law is valid over the concentration range 0.5-14.1 mg l^{ - 1} for EPH and 0.5-14.5 mg l^{ - 1} for IPH. The …
Electron Ionization Mass Spectrometric Studies Of Homalicine Tertraacetate, Dihydrohomalicine Tetraacetate And Related Compounds, Nasim Hasan Rama, Muhammad Tahir Hussain
Electron Ionization Mass Spectrometric Studies Of Homalicine Tertraacetate, Dihydrohomalicine Tetraacetate And Related Compounds, Nasim Hasan Rama, Muhammad Tahir Hussain
Turkish Journal of Chemistry
Electron Ionization mass spectra of homalicine tetraacetate (3), dihydrohomalicine tetraaetate (4) and related compounds (5,6) are described with the help of EIMS. The molecular formulae are further confirmed by HREIMS peak matching of molecular ion peaks exhibited by EIMS.
Determination Of Cadmium By Faas After Solid-Phase Extraction Of Its 1-Benzylpiperazinedithiocarbamate Complex On Microcrystalline Naphthalene, Hasan Cesur, Beki̇r Bati
Determination Of Cadmium By Faas After Solid-Phase Extraction Of Its 1-Benzylpiperazinedithiocarbamate Complex On Microcrystalline Naphthalene, Hasan Cesur, Beki̇r Bati
Turkish Journal of Chemistry
By using 1-benzylpiperazinedithiocarbamate (1-BPzDC) as a new reagent, a method of solid-phase extraction is described for the pre-concentration of cadmium in water samples prior to its determination by flame atomic absorption spectrometry (FAAS). This method is based on the fact that cadmium forming in aqueous phase cadmium 1-benzylpiperazinedithiocarbamate complex (Cd(1-BPzDC)_{2}) can be extracted with microcrystalline naphthalene on solid phase, then back-extracted with potassium cyanide solution into aqueous phase and measured by FAAS. The optimum experimental parameters for the extraction and back-extraction of cadmium were investigated. The obtained recovery was nearly 97% when the enrichment factor was 500 for spiked cadmium …
Determination Of The Protonation Constants Of Some Substituted Salicylideneanilines By The Spectrophotometric Method In Ethanol-Water Mixtures, M. Abdülkadi̇r Akay, Esi̇n Canel, Esma Kiliç, Fi̇tnat Köseoğlu
Determination Of The Protonation Constants Of Some Substituted Salicylideneanilines By The Spectrophotometric Method In Ethanol-Water Mixtures, M. Abdülkadi̇r Akay, Esi̇n Canel, Esma Kiliç, Fi̇tnat Köseoğlu
Turkish Journal of Chemistry
Protonation constants of salicylideneaniline and methyl-, ethyl-, methoxy- fluoro-, chloro-, bromo- and iodo- substituted salicylideneanilines were determined by spectrophotomeric titrimetry in 10, 30, 50 and 70% ethanol-water mixtures at constant ionic strength and at 25^{o}C. The results obtained from this work were compared with those obtained using the potentimetric method. The difference between the results found with these two methods was approximately \pm $ 0.20 logK units. The spectrophotometric method was judged to be more suitable than the potentiometric method for halogen substituted salicylideneanilines with the low logK values and in the solvent mixture containing 10% ethanol, due to the …
Automated Recognition Of Ergogenic Aids Using Soft Independent Modeling Of Class Analogy (Simca), M. Praisler, J. Van Bocxlaer, A. De Leenheer, D. L. Massart
Automated Recognition Of Ergogenic Aids Using Soft Independent Modeling Of Class Analogy (Simca), M. Praisler, J. Van Bocxlaer, A. De Leenheer, D. L. Massart
Turkish Journal of Chemistry
The introduction of effective drug testing procedures in doping control reduced, but did not eliminate, their abuse by athletes. The most important analytical challenge is the recognition of the new analog compounds. In attempts to circumvent existing controlled substance laws, slightly modified chemical structures (by adding or changing substituents at various positions on the banned molecules) are used. As a result, no substance belonging to a prohibited class may be used nowadays, even if it has not been specifically listed. We present a chemometric procedure acting as an automated GC-FTIR screening test detecting the molecular structural similarity of unknown compounds …
Determination Of Manganese And Iron In Magmatic Rocks After Ultrasonic Leaching By Flame Aas, M. Hi̇kmet Özkan, Mehmet Akçay
Determination Of Manganese And Iron In Magmatic Rocks After Ultrasonic Leaching By Flame Aas, M. Hi̇kmet Özkan, Mehmet Akçay
Turkish Journal of Chemistry
An alternative sample preparation method has been developed for destructive analysis of magmatic rock sample. The method simply included the crushing, HF treatment and 1% HCl leaching steps of the rock samples under ultrasonic effects. There is no need to exhaust all of the sample through the operation. A reproducible and representative, partial recovery of an analyte was expected in a procedural sequences consisting of strictly defined steps. The changes in analyte recoveries were investigated by sample grain size, sample mass, applied ultrasonic power and sonication time. The optimum recovery conditions were examined. In addition, the kinetics of the dissolution …
Extraction Equilibria Of Nicotinic Acid Using Alamine 300/Diluent And Conventional Solvent Systems, Aynur Şenol
Extraction Equilibria Of Nicotinic Acid Using Alamine 300/Diluent And Conventional Solvent Systems, Aynur Şenol
Turkish Journal of Chemistry
The distribution of nicotinic acid between water and Alamine 300 (tri-n-octylamine) dissolved in various (proton-donating and -accepting, polar and nonpolar) diluents, and a comparison with the extraction equilibria of pure diluent alone were studied at 298 K and a phase ratio of 1:1 (v/v). The cyclic alcohol/amine system yielded the highest synergistic extraction efficiency. The strength of the complex solvation was found to be reasonably high for halogenated aliphatic hydrocarbons and nitrobenzene, activating mainly the formation of the acid_{1}-amine_{1} structure. The influence of the acid structure over distribution was evaluated through comparing the extractabilities of three acids containing different functional …
Dehydration Behaviour Of Borax Pentahydrate To Anhydrous Borax By Multi-Stage Heating In A Fluidized, Ömer Şahi̇n, A. Nusret Bulutcu
Dehydration Behaviour Of Borax Pentahydrate To Anhydrous Borax By Multi-Stage Heating In A Fluidized, Ömer Şahi̇n, A. Nusret Bulutcu
Turkish Journal of Chemistry
In order to optimize the anhydrous borax process in a fluidized bed calcinator, it is absolutely necessary to study the dehydration behaviour of borax pentahydrate. It was found that the basic feature of the dehydration of borax pentahydrate to anhydrous borax is concerned with the conditions employed. The bulk density and sodium borate content of the end product were determined to be a function of number of stages of temperature of the dehydration period in the fluidized bed. It was observed that bulk density also depends on the number of moles of water remaining in the borax pentahydrate structure. High …
Partially Purification And Characterization Of Polyphenol Oxidase Of Quince, Hülya Yağar, Ayten Sağiroğlu
Partially Purification And Characterization Of Polyphenol Oxidase Of Quince, Hülya Yağar, Ayten Sağiroğlu
Turkish Journal of Chemistry
Polyphenol oxidase (PPO, EC 1.14.18.1) was extracted from quince (Cydonia oblonga) by using 0.1 M phosphate buffer, pH 6.8. The polyphenol oxidase of quince was partially purified by (NH_{4})_{2}SO_{4} and dialysis. Substrate specificity experiments were carried out with catechol, pyrogallol, L-DOPA, p-cresole and tyrosine. Catechol was the most suitable substrate compound for quince PPO. The Michaelis constants were 4.54 mM, 7.35mM and 17.8 mM for catechol, pyrogallol and L-DOPA, respectively at 25^oC. The optimum pH and temperature were determined with the specific substrate catechol as 8.0 and 40$^oC, respectively. Of eight inhibitors tested L-cysteine, ascorbic acid and potassium cyanide were …
Vibrational Spectra And Assignments Of Cis- And Trans-1,4-Polybutadiene, P. Nallasamy, P.M. Anbarasan, S. Mohan
Vibrational Spectra And Assignments Of Cis- And Trans-1,4-Polybutadiene, P. Nallasamy, P.M. Anbarasan, S. Mohan
Turkish Journal of Chemistry
The Raman spectra of cis- and trans-1,4- polybutadiene were recorded in the region 100-4000 cm^{-1} and its infrared spectra were also measured in the wave number range 200--4000 cm^{-1}. The spectra were completely analysed. Probable assignments to observed bands were made with the help of intensities and normal co-ordinate analysis. The calculated normal frequencies were in good agreement with the experimental ones.
An Investigation Of Some Parameters On Electrorheological Properties Of Polypyrrole Suspensions, Deni̇z Şahi̇n, Beki̇r Sari, Hali̇l İbrahi̇m Ünal
An Investigation Of Some Parameters On Electrorheological Properties Of Polypyrrole Suspensions, Deni̇z Şahi̇n, Beki̇r Sari, Hali̇l İbrahi̇m Ünal
Turkish Journal of Chemistry
In this study, polypyrrole (PPy) was synthesized by cationic addition polymerization. The polymer was characterized by FTIR spectroscopy, scanning electron microscopy (SEM), particle size, magnetic susceptibility, and four-probe conductivity measurements. From the magnetic susceptibility measurements, it was found that the polymer was a bipolaron conducting mechanism. From the particle size measurements, the average particle size of PPy was determined to be 3.2 \mu m. Suspensions of this polymer were prepared in silicone oil, mineral oil, trioctyltrimellitate (TOTM), dioctylphthalate (DOP) and marlotherm-s in different concentrations (5-20%, m/m). The electrorheological (ER) properties of these suspensions were investigated under various d.c. electric field …
Synthesis, Characterization And Biological Activity Of Triorganotin Carboxylates Containing Germanium, Muhammad Aziz Choudhary, Muhammad Mazhar, Saqib Ali, Umm-E Salma, Saima Ashraf, Abdul Malik
Synthesis, Characterization And Biological Activity Of Triorganotin Carboxylates Containing Germanium, Muhammad Aziz Choudhary, Muhammad Mazhar, Saqib Ali, Umm-E Salma, Saima Ashraf, Abdul Malik
Turkish Journal of Chemistry
Some new triorganotin carboxylates containing germanium with general formulae (R^{1}GeCHR^{2}CH_{2}COO) Sn(CH_{2}C(CH_{3})_{3})_{3} where R^{1} = N(CH_{2}CH_{2}O)_{3} and C_{6}H_{5}, R^{2} = C_{6}H_{5}, p-C_{6}H_{4}OCH_{3} and o-/p-C_{6}H_{4}F were synthesized and characterized by elemental analysis, infrared, multinuclear (^{1}H, ^{13}C, ^{119}Sn) NMR and mass spectrometry. Antibacterial activity of these compounds was evaluated against the standard drugs ampicilline and amoxicilline, and found to be more active in some cases than the standard drugs.
Phenolic Constituents From Phlomis Lycia, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Yukio Ogihara
Phenolic Constituents From Phlomis Lycia, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Yukio Ogihara
Turkish Journal of Chemistry
From the aerial parts of Phlomis lycia L. (Labiatae) a lignan glucoside, (-)-dihydrodehyrodiconiferyl alcohol-9-O-\beta -D-glucopyranoside (1); a caffeic acid ester, chlorogenic acid (2); three phenylethanoid glycosides, forsythoside B (3), alyssonoside (4) and leucosceptoside B(5); and two iridoid glucosides, lamiide (6) andauroside (7), were isolated. The structure elucidation of the isolated compounds was carried out by spectroscopic (UV, IR, 1D- and 2D-NMR, FAB-MS) methods. (-)-Dihydrodehyrodiconiferyl alcohol-9-O-\beta -D-glucopyranoside (1) and chlorogenic acid (2) were isolated for the first time from Phlomis species in this study.
A New Synthesis Of Bromobenzotropones: Oxidation Of 8-Bromo-5 H -Benzo[A]Cycloheptene, Ari̇f Daştan, Y. Kemal Yildiz, Cavi̇t Kazaz, Meti̇n Balci
A New Synthesis Of Bromobenzotropones: Oxidation Of 8-Bromo-5 H -Benzo[A]Cycloheptene, Ari̇f Daştan, Y. Kemal Yildiz, Cavi̇t Kazaz, Meti̇n Balci
Turkish Journal of Chemistry
The oxidation of 8-bromo-5H-benzo[a]cycloheptene with some oxidation reagents was studied. 2,3- and 4,5-benzotropone derivatives were obtained. The structures of the bromobenzotropones were determined by ^{1}H- and ^{13}C-NMR data.
An Investigation Of The Interaction Of 4-Membered Rings With Adjacent Carbanion Centers, Özden Özel Güven, N. Beki̇r Peyni̇rci̇oğlu
An Investigation Of The Interaction Of 4-Membered Rings With Adjacent Carbanion Centers, Özden Özel Güven, N. Beki̇r Peyni̇rci̇oğlu
Turkish Journal of Chemistry
A series of cyclobutylcarbinyl phenyl ketones was prepared and the rates of base catalyzed hydrogen-deuterium exchange of \alpha -hydrogen atoms were compared with those of appropriate model compounds, to test the validity of an earlier finding, which suggested that a four-membered ring, like the three-membered ring, has the ability to stabilize an adjacent carbanion center. In this study, unlike the cyclopropyl group, no clearly defined stabilization of the adjacent carbanion center was detected by the 1-phenyl- and 1-p-nitrophenyl- substituted cyclobutyl groups and only a very slight rate enhancement by the 3-phenylcyclobutyl group was detected. Attempts to detect a stabilization of …
Synthesis And Electronic Structure Of New Aryl- And Alkyl-Substituted 1,3,4-Oxadiazole-2-Thione Derivatives, Feray Aydoğan, Zuhal Turgut, Nüket Öcal, Safi̇ye Sağ Erdem
Synthesis And Electronic Structure Of New Aryl- And Alkyl-Substituted 1,3,4-Oxadiazole-2-Thione Derivatives, Feray Aydoğan, Zuhal Turgut, Nüket Öcal, Safi̇ye Sağ Erdem
Turkish Journal of Chemistry
New 5-alkyl and 3-(2,4-dimethylphenyl) substituted 1,3,4-oxadiazole-2-thione derivatives were synthesized by the ring closure reactions of various acylhydrazides with carbon disulphide. Mannich bases for some of these compounds were also synthesized by condensation with benzaldehyde and primary amines. All new compounds were characterized by spectral data. Most of them were tested for their antibacterial and antituberculostatic activity. Molecular orbital calculations at the HF/6-31G** level were also performed to determine the optimized geometrical structures. Results indicated electron delocalization over several atoms of the ring. An additional study on the tautomeric equilibrium between 1,3,4-oxadiazole-2-thione and its thiol form showed that the thione tautomer …
Iridoid And Phenylpropanoid Glycosides From Phlomis Grandiflora Var. Fimbrilligera And Phlomis Fruticosa, Tayfun Ersöz, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Ali̇ Arslan Dönmez
Iridoid And Phenylpropanoid Glycosides From Phlomis Grandiflora Var. Fimbrilligera And Phlomis Fruticosa, Tayfun Ersöz, İclal Saracoğlu, Ü. Şebnem Harput, İhsan Çaliş, Ali̇ Arslan Dönmez
Turkish Journal of Chemistry
From the aerial parts of Phlomis grandiflora var. fimbrilligera, two iridoid glucosides, 8-epi-loganin (1) and auroside (2), together with five phenylethanoid glycosides, forsythoside B (3), alyssonoside (4), verbascoside (5), hattushoside (6) and phlomisethanoside (7), were isolated. Iridoid glucosides auroside (2) and lamiide (8) and phenylethanoid glycosides, forsythoside B (3), alyssonoside (4), and verbascoside (5) as well as a lignan glucoside, syringaresinol-4 ' -O-\beta -D-glucoside (9), were characterized from the overground parts of P. fruticosa. The structures of the isolates were elucidated by means of one and two dimensional (COSY, HSQC and HMBC) NMR techniques and ESI MS.
Iridoid And Phenylethanoid Glycosides From Euphrasia Pectinata, Tayfun Ersöz, M. Zi̇ver Berkman, Deni̇z Taşdemi̇r, İhsan Çaliş, Chris M. Ireland
Iridoid And Phenylethanoid Glycosides From Euphrasia Pectinata, Tayfun Ersöz, M. Zi̇ver Berkman, Deni̇z Taşdemi̇r, İhsan Çaliş, Chris M. Ireland
Turkish Journal of Chemistry
Two specimens of Euphrasia pectinata collected from different regions of northern Anatolia were studied to determine their iridoid and phenylethanoid glycosides. Four iridoid glucosides, aucubin (1), euphroside (2), ixorodoside (3), and boschnaloside (4), and two phenylethanoid glycosides, acteoside (5) and leucosceptoside A (6), were isolated, and characterized from the aerial parts of E. pectinata} collected from Zigana pass (Trabzon). From the aerial parts of E. pectinata} collected from Kartalkaya (Bolu), a phenethyl alcohol glycoside, decaffeoylacteoside (7), was isolated in addition to previously isolated compounds. The structures of the isolated compounds were established by spectroscopic evidence.
Diterpenes From Sideritis Sipylea And S. Dichotoma, Gülaçti Topçu, Ahmet C. Gören, Turgut Kiliç, Y. Kemal Yildiz, Gülendam Tümen
Diterpenes From Sideritis Sipylea And S. Dichotoma, Gülaçti Topçu, Ahmet C. Gören, Turgut Kiliç, Y. Kemal Yildiz, Gülendam Tümen
Turkish Journal of Chemistry
Two Sideritis species afforded eleven kaurene and one beyerene diterpenes. Structures of the compounds from Sideritis sipylea} were elucidated as linearol (1), 7-epicandicandiol (2), sideridiol (3), siderol (4), isolinearol (5), isosidol (6) and epoxyisolinearol (7). Linearol was treated with m -chloroperbenzoic to afford its analogues ent-3\beta ,7\alpha ,17-trihydroxy-18-acetoxykaur-15-ene (1a) and ent}-7\alpha ,17,18-trihydroxy-3\beta -acetoxykaur-15-ene (1b) as new compounds. From the second species, Sideritis dichotoma, the kaurenes sideridiol (3) siderol (4), ent-7\alpha ,18-dihydroxy-15\beta ,16\beta -epoxykaurane (8)}, ent}-7\alpha -acetoxy,18-hydroxy-15\beta ,16\beta -epoxykaurane (9), ent-7\alpha -acetoxy-15,18-dihydroxy-kaur-16-ene (10), ent-7\alpha ,15,18-trihydroxykaur-16-ene (11) and the beyerene ent-7\alpha ,18-dihydroxybeyer-15-ene (12) were isolated. Structural elucidation is based on NMR techniques …
Pyrrolizidine Alkaloids From Symphytum Sylvaticum Boiss. Subsp. Sepulcrale. (Boiss.& Bal.) Greuter & Burdetvar. Sepulcrale And Symphytum Aintabicum Hub.- Mor. & Wickens, Semra Kurucu, Murat Kartal, Muhammad Iqbal Choudhary, Gülaçti Topçu
Pyrrolizidine Alkaloids From Symphytum Sylvaticum Boiss. Subsp. Sepulcrale. (Boiss.& Bal.) Greuter & Burdetvar. Sepulcrale And Symphytum Aintabicum Hub.- Mor. & Wickens, Semra Kurucu, Murat Kartal, Muhammad Iqbal Choudhary, Gülaçti Topçu
Turkish Journal of Chemistry
Pyrrolizidine alkaloid (Echimidine-N-oxide) was isolated from Symphytum sylvaticum Boiss. subsp. sepulcrale (Boiss. & Bal.) Greuter & Burdet var. sepulcrale and pyrrolizidine alkaloid (Echimidine) was isolated from Symphytum aintabicum Hub. - Mor. & Wickens. The structures of the isolated compounds were elucidated based on IR, EIMS, ^{1}H, and ^{13}C NMR analysis and also on 2D NMR (COSY, HMBC, HMQC) experiments.
Thermodynamic And Kinetic Parameters Concerning Complex Formation Between 3-Hydroxy- And 1-Aminopyrene And Pyridine, Nursel Acar, Özgül Koçak
Thermodynamic And Kinetic Parameters Concerning Complex Formation Between 3-Hydroxy- And 1-Aminopyrene And Pyridine, Nursel Acar, Özgül Koçak
Turkish Journal of Chemistry
Systems formed by the pyrene derivatives 3-hydroxypyrene and 1-aminopyrene with pyridine were studied. The thermodynamic and kinetic parameters of the systems were calculated using the changes in the absorption and emission spectra which occur due to hydrogen bond or complex formation. The decrease of the formation rate constant in the series methylcyclohexane, benzene, and o-chlorotoluene may be due to a more difficult formation of the hydrogen bond complex due to the increase of the dielectric constant in the solvent series.
Glycine Transport Through A Charged Polysulfone Cation Exchange Membrane, Nuri̇ Ünlü, Hüseyi̇n Kara, Mustafa Ersöz
Glycine Transport Through A Charged Polysulfone Cation Exchange Membrane, Nuri̇ Ünlü, Hüseyi̇n Kara, Mustafa Ersöz
Turkish Journal of Chemistry
The transport of glycine through a charged polysulfone cation exchange membrane was studied as a function of pH at different initial conditions of less than pH 5.9 and the glycine permeability was explained under the experimental conditions as pH dependent interfacial transport. The glycine permeability increases with a decreasing pH in the receiver phase. The largest permeability was obtained if the initial pH on the source side was pH 5.9 and that on the opposite side was pH 2.0. The transport phenomena can be explained by the interfacial transport based on the interfacial chemical reaction (protonation, deprotonation or ion-exchange) between …
Solvent, Temperature And Concentration Effects On The Adsorption Of Poly(N-Butyl Methacrylate) On Alumina From Solutions, Nursel Pekel, Olgun Güven
Solvent, Temperature And Concentration Effects On The Adsorption Of Poly(N-Butyl Methacrylate) On Alumina From Solutions, Nursel Pekel, Olgun Güven
Turkish Journal of Chemistry
Adsorption of poly(n-butyl methacrylate) (PnBMA) on alumina from solution was studied by UV and FT-IR Photoacoustic Spectroscopy techniques. The effects of the solvent, temperature, concentration, and molecular weight of the polymer on adsorption were investigated. Three solvents, cyclohexane, carbon tetrachloride and benzene, were employed. The adsorption was dependent on molecular weight and much more polymer was adsorbed in cyclohexane than in other solvents on the alumina surface. A decrease in adsorption was observed with increasing temperature. The results are in conformity with Langmuir's isotherm. The differences observed in Langmuir parameters were explained by polymer-polymer, polymer-solvent, polymer-adsorbent, and solvent-adsorbent interactions.
The Kinetics And Mechanism Of Oxidation Of Vanillin By Diperiodatonickelate(Iv) In Aqueous Alkaline Medium, Chandrashekhar Kathari, Pandurang Pol, Sharanappa Nandibewoor
The Kinetics And Mechanism Of Oxidation Of Vanillin By Diperiodatonickelate(Iv) In Aqueous Alkaline Medium, Chandrashekhar Kathari, Pandurang Pol, Sharanappa Nandibewoor
Turkish Journal of Chemistry
The title reaction was investigated in aqueous alkaline medium. A first order dependence in diperiodatonickelate (IV) (DPN) and an apparent fractional order in both vanillin and alkali were obtained. Periodate has a retarding effect on the reaction. The effect of added products and the ionic strength of the reaction medium have no significant effect on the reaction rate. A decrease in the dielectric constant of the medium decreases the rate of reaction. Effects of temperature on the rate of reaction were studied. A mechanism based on experimental results was proposed, and constants involved in the mechanism were evaluated. A good …
Synthesis, Spectral And Fungicidal Studies On Dioxobridged Binuclear Niobium(V) And Tantalum(V) Complexes Of N-Alkylphenothiazines, Boregowda Keshavan, Hunasegala Kempe Gowda
Synthesis, Spectral And Fungicidal Studies On Dioxobridged Binuclear Niobium(V) And Tantalum(V) Complexes Of N-Alkylphenothiazines, Boregowda Keshavan, Hunasegala Kempe Gowda
Turkish Journal of Chemistry
Six new dioxobridged binuclear complexes of the type [MO(L)Z]_{2}Z, where M=niobium(V) or tantalum(V), L=N-alkylphenothiazines (NAPs) and Z=tartrate and oxalate for niobium and tantalum respectively, were synthesized. The stoichiometry of the complexes was proposed on the basis of elemental analyses, molar conductance, magnetic and thermal data. The coordination behaviour of the ligands was determined with the help of spectroscopic studies. The fungicidal activity of the complexes was evaluated.