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Öğe Asymmetric Organocatalytic Efficiency of Synthesized Chiral ?-Amino Alcohols in Ring-Opening of Glycidol with Phenols(Springer, 2012) Aral, Tarik; Karakaplan, Mehmet; Hosgoren, HalilA series of novel chiral beta-amino alcohols 3-5 and 7-10 were synthesized by regioselective ring opening of epoxides and chiral amines with a straightforward method in high yields (up to 99 %). Kinetic resolution of racemic glycidol with phenols was achieved by using chiral amino alcohols as organocatalysts. Amino alcohols 5, 8 and 10 exhibited the highest enantioselectivities with p-cresol, phenol, and p-methoxyphenol by 63, 65, 58 % ee, respectively. The moderate enantioselectivities were observed with catalyst 9b towards all the nucleophiles (34-48 % ee). The ee values of the desired 3-aryloxy-1,2-diols were determined by HPLC. This study presents an attractive tool for the synthesis of beta-blockers and structurally complex molecules.Öğe Catalytic properties of heteropoly acid H3PW12O40 supported-on Turkish bentonite(Asian Journal Of Chemistry, 2008) Tonbul, Yalcin; Hosgoren, HalilCatalysts based on tungstophosphoric acid on Turkish bentonite were obtained. The influence of the heteropoly acid content, in five different concentrations, was studied. The catalysts have been characterized using gas adsorption analysis (BET), thermogravimetry and surface acidity of samples were determined by pyridine adsorption using fourier transform infrared technique, The catalytic activity of these materials was tested for the esterification reactions of acetic acid with benzyl alcohol. The results showed that all catalysts have mesopores, thermal stability of samples higher than bulk heteropoly acid. According to FTIR results, the catalyst samples have medium Lewis acidity, but weak Bronsted acidity.Öğe Chiral lariat ethers as membrane carriers for chiral amino acids and their sodium and potassium salts(Pergamon-Elsevier Science Ltd, 2009) Aydin, Isil; Aral, Tarik; Karakaplan, Mehmet; Hosgoren, HalilFour chiral lariat ethers 8-11 containing a (p-methoxyphenoxy) methyl side arm were used for chiral discrimination of amino acids in their zwitterionic form or as potassium and sodium salts in transport across a bulk chloroform membrane with satisfactory selectivity. The carriers that were employed exhibited different transport selectivity relative to the amino acids and their Salts under study. The D/L selectivity strongly depends on the amino acids or their salts, and in some cases reverse selectivity has been obtained. The best selectivity was obtained in the case of tyrosine and its potassium salts for all carriers. The transport rates of amino acids and their salts were found to be controlled by factors such as the structure of the carriers and amino acids or their salts. Among these factors, it was also found that the side arm of the lariat ethers plays an important role in the transport process. As a consequence, the main goal of our investigation was to separate the chiral amino acids through liquid membranes. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Chiral separation of amino acids using a chiral crown ether by impregnation on a polymeric support and monoamine modified silica gel(Pergamon-Elsevier Science Ltd, 2006) Seyhan, Serap; Turgut, Yilmaz; Merdivan, Melek; Hosgoren, HalilA chiral monoaza-15-crown-5 ether derivative was prepared from L-Leucinol and used as a chiral stationary phase. The new chiral stationary phases CSP-1 and CSP-2 were employed in separating the enantiomers of the sodium and potassium salts of amino acids. The sodium and potassium salt of the D-enantiomers of all amino acids (PhyAlaNa, PhyAlaK and PhyGlyNa, PhyGlyK, and TrpNa, TrpK) show higher selectivity than the L-enantiomers for both CSP-1 and CSP-2. (c) 2006 Elsevier Ltd. All rights reserved.Öğe The enantiomeric recognition of chiral organic ammonium salts by chiral pyridino-macrocycles bearing aminoalcohol subunits(Pergamon-Elsevier Science Ltd, 2009) Ozer, Hayriye; Kocakaya, Safak Ozhan; Akgun, Abuzer; Hosgoren, Halil; Togrul, MahmutPyridine-based macrocycles were prepared by treating 2,6-bis[[2'6'-bis(bromomethyl)-4'-methylphenoxy]methyl]pyridine 3 with the appropriate chiral aminoalcohols. The enantiomeric recognition of these macrocycles bearing aminoalcohol subunits of the pyridinocrown type ligand was evaluated for chiral organic ammonium salts by UV titration. The important differences were observed in the K-a values of (R)-Am2 and (S)-Am2 for (S,S,S)-1, (S,SS)-2 and (S,S,S)-3 hosts, K-S/K-R = 5.0, K-S/K-R = 2.4 and K-S/K-R = 5.0. respectively. There seems to be a general tendency for hosts to recognise (S)-enantiomers for both Am1 and Am2. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Enantioselective complexation of chiral lariat crown ethers and chiral primary alkylammonium perchlorates(Tubitak Scientific & Technological Research Council Turkey, 2011) Koylu, M. Zafer; Aral, Tarik; Karakaplan, Mehmet; Kocakaya, Safak Ozhan; Hosgoren, HalilIn order to investigate the enantiomeric recognition abilities toward 2 chiral alkylammonium perchlorates (AmI, AmII) by H-1-NMR titration method in CDCl3, 4 chiral lariat ethers 8-11 with a (p-methoxyphenoxy) methyl flexible side arm were used. The most effective enantiomeric recognition was obtained by LCEs 9 and 11 toward AmII, by K-R/K-S 6.58 and K-S/K-R 6.63, respectively. The effect of macroring size, subunit of macroring, and side arm appeared to have strong influence on the binding ability of these alkylammonium ions.Öğe ?-Hydroxyamide derivatives of salicylic acid as organocatalysts for enantioselective reductions of prochiral ketones(Pergamon-Elsevier Science Ltd, 2013) Turgut, Yilmaz; Azizoglu, Murat; Erdogan, Asli; Arslan, Nevin; Hosgoren, HalilIn order to find the most effective catalyst for the enantioselective reduction of a prochiral ketone, a series of novel beta-hydroxyamide derivatives of salicylic acid and chiral amino alcohols were synthesized. Different substituted prochiral ketones have been reduced in high yield (up to 99%) and the corresponding secondary alcohols are formed with good enantiomeric excess (up to 86%). The mechanism of this type of catalyst can be explained by considering the reaction mechanism for the CBS catalyst. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Improvement of Synthesis and Dielectric Properties of Polyurethane/Mt-QASs+ (Novel Synthesis)(Springer, 2016) Baysal, Gulay; Aydin, Haluk; Hosgoren, Halil; Uzan, Serhat; Karaer, HaticePolyurethane-based nanocomposites were prepared and their dielectric properties were characterized. Polyurethane (PU) composites were prepared with different organoclay content (1, 3, 5, and 10 wt% for all cases). The composites included quaternary ammonium salts such as 1-methyl-di-octyl-1 phenyl ammonium iodide (QAS-1), 1-methyl-di-nonyl-1 phenyl ammonium iodide (QAS-2), and 1-methyl-di-dodecyl-1 phenyl ammonium iodide (QAS-3) which were newly synthesized for modification of Na+-montmorillonite. Addition of aluminum silicate enhanced the dielectric properties at a constant concentration. Dielectric constants of nanocomposites compounded with 3 %- and 5 %-organoclay were close in value. The characterization of PU/organoclay composites was carried out using Fourier transform infrared and X-ray diffraction.Öğe Investigation of Antimicrobial Properties of QASs+ (Novel Synthesis)(Maik Nauka/Interperiodica/Springer, 2018) Baysal, Gulay; Aydin, Haluk; Uzan, Serhat; Hosgoren, HalilQuaternary ammonium salts (QASs) are bioactive materials known for their antimicrobial effects. However, it is difficult to provide desirable quaternary ammonium salts. Thus, firstly new quarternary ammonium salts which are not in the literature were synthesized and organoclays were prepared with different quarternary ammonium salts content. The organoclays included quaternary ammonium salts such as N,N-di (3-methyl butyl)-N-(1-phenylethyl)-N-methyl ammonium Iodide (QAS-1), N,N-dipentil-N-(1-phenylethyl)-N-methyl ammonium Iodide (QAS-2), and N,N-dihexcyl-N-(1-phenylethyl)-N-methyl ammonium Iodide (QAS-3) which were newly synthesized for modification of Na+-montmorillonite (Na+-Mt) and were characterized by nuclear magnetic resonance spectroscopy (NMR). Synthesized organoclays were characterized by using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Characterization results proved that the modification is performed with high performance and as seen in the XRD results, the interstratum distances increased considerably and the diffraction angles decreased. The antimicrobial activity of the organoclays against Staphylococcus aureus and Escherichia coli were studied in detail and were obtained much larger inhibition zones than similar studies. QAS-3-Mt organoclay showed the maximum of antimicrobial activity against S. aureus and E. coli. As is known, organoclay comes among the fillers that play the most effective role in the synthesis of composite materials. In this context, the product we have synthesized is unique and can be used for many purposes.Öğe Investigation of some 1,3-diols for the requirements of solvent extraction of boron: 2,2,6-trimethyl-1,3 heptanediol as a potential boron extractant(Tubitak Scientific & Technological Research Council Turkey, 2007) Tural, Bilsen; Tural, Servet; Hosgoren, HalilEighteen 1,3-diols were syntesized and their structure and distribution ratio for the solvent extraction of boron were studied. Diols with a high distribution ration (DB(OH)3 > 10) were investigated for the requirements of solvent extraction of boron. Their extraction capacity, and solubility in aqueous phase and in organic diluents were investigated by comparison to 2-ethyl-1,3-hexanediol (EHD), which is widely used as a boron extractant. Among a series of 1,3 diols, 1-benzyl-2,2-dimethyl-1,3-propanediol (4a) and 2,2,6-trimethyl-1,3-heptanediol (3a) were found to have very low solubility in the aqueous phase compared to the others. IPD (3a) was found to have a high solubility in aliphatic diluents such as kerosene. IPD, which has good solubility properties for the solvent extraction of boron, was studied in detail, including dependence of pH, diol concentration, and stripping facility, and in various organic diluents.Öğe Novel bis(aminoalcohol)oxalamide organogelators and their diglycolylamide analogs: evaluation of gelation efficiency in various organic fluids(Tubitak Scientific & Technological Research Council Turkey, 2017) Colak, Mehmet; Baris, Deniz; Pirinccioglu, Necmettin; Hosgoren, HalilThree modular types of bis(aminoalcohol)oxalamides (1, 4, and 7) and bis(aminoalcohol)diglycolylamide (8) gelators have been prepared by the reaction of the respective aminoalcohols with oxalyl and digycolyl methylesters as potential low-molecular-weight organogelators. The gelation properties of these amides have been evaluated in various aromatic organic solvents (xylene, toluene, isopropyl benzene, and aromatic ether type organic fluids such as anisole or alpha-phenylethylmethylether) as well as the long-chain aliphatic alcohols (1-hexanol, 1-octanol, 2-octanol, and aromatic 1-phenylethanol). The compounds with sec-butyl and ethyl side chains produce good gelation properties in both aromatic and other organic fluids. Furthermore, the common oxalamide linker present in the gelators was replaced by an extended diglycolylamide linker (8) and its behaviors were compared with the benzylic oxalamide analog (3). The gelator (8) gives the best results with aromatic fluid and lauric acid ethyl ester. H-1 NMR studies reveal the existence of temperature dependent network assembly/dissolution equilibrium and produce K-gel. FTIR was employed to see the effect of hydrogen bonding in the formation of gel network. Thermodynamic parameters regarding gel-to-sol transition were collected with van't Hoff relationships.Öğe Novel C2-symmetric macrocycles bearing diamide-diester groups(Amer Chemical Soc, 2008) Sunkur, Murat; Baris, Deniz; Hosgoren, Halil; Togrul, MahmutWe synthesized a series of novel macrocycles with diamide-diester groups (S,S)-1, (S,S)-2, (S,S)-3, and (R,R)-1, derived from dimethyloxalate and amino alcohols by high dilution technique, and evaluated enantiomeric recognition properties of these macrocycles toward primary alkyl ammonium salts by H-1 NMR titration. Taking into account the host employed, important differences were observed in the K-a values of (R)-Am and (S)-Am for (S,S)-1 and (R,R)-1 hosts, K-S/K-R = 5.55 and K-R/K-S = 3.65, Delta Delta G(o) = 0.43 and -0.32 kJ mol(-1), respectively. There seems a general tendency for the host to include the guests with the same absolute configuration.Öğe Organogels as novel carriers for dermal and topical drug delivery vehicles(Pergamon-Elsevier Science Ltd, 2016) Uzan, Serhat; Baris, Deniz; Colak, Mehrnet; Aydin, Haluk; Hosgoren, HalilAminoalcohol based bis-(aminoalcohol)oxalamides (BAOAs) (1,6-amino alcohol=leucinol, isoleucinol, valinol, phenyiglycinol, phenylalaninol and 2-amino-1-butanol) have been explored to develop drug depot systems and illustrated as a novel dermal and topical drug delivery vehicle for non-steroidal anti-inflammatory drug molecules. FAE's (Fatty acid ethyl and isopropyl esters) with different chain lengths, ethyl laurate, ethyl myristate, ethyl palmitate, isopropyl laurate, isopropyl myristate, isopropyl palmitate, have been chosen as they are biocompatible organic fluids used typically in cosmetic industry. Ibuprofen (Ib), acting as a model drug, was entrapped in the supramolecular organogels. The release behavior of Ib molecules in the supramolecular organogels was investigated by using UV-vis spectroscopy. The influence of the organogelator and drug concentration, pH values of the accepting media, and nature of solvent (different FAE's) on the release behavior of Ib was investigated under static conditions. The results indicated that the release rate of Ib from the supramolecular organogels was effectively retarded with an increase of the organogelator concentration. Also, the release rates of Ib increased on increasing the Ib content. Furthermore, the release behavior of Ib was found to be different at various pH values in buffers as accepting media. The study of the release kinetics indicated that the release behavior of Ib was in accord with the Higuchi equation and the diffusion-controlled mechanism involved in the Fickian model. These observations indicate that bis-(aminoalcohol)oxalamides gels may act as delivery vehicles for non-steroidal anti-inflammatory drug molecules and also show that the release profiles for such systems can be fine-tuned by the correct choice of gelator-FAE combination. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Polymer supported 5,10,15,20-tetrakis(phenoxy acetic acid)porphyrin derivative for separation and preconcentration of d- and f-electron metals(Springer Wien, 2008) Seyhan, Serap; Merdivan, Melek; Demirel, Nadir; Hosgoren, Halil5,10,15,20-tetrakis(phenoxy acetic acid) porphyrin (PAAP) was covalently linked to Merrifield chloromethylated resin. Characterization of PAAP and the modified polymeric matrix were performed by H-1 NMR, FTIR and elemental analysis. The sorbent was used for the separation and enrichment of the d-electron metals (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) at pH 6-8 and of the f-electron metals U(VI) and Th(IV) at pH 4-5. The metals ions were preconcentrated with a concentration factor range of 115-215 and then determined by flame atomic absorption spectrometry or visible spectrophotometry using Arsenazo(III). The retained metals were eluted with 2.0 mol L-1 HNO3 in the case of the d-electron metals and 0.1/0.25mol L-1 HCl in the case of the f-electron metals. The procedure was validated by analyzing the NIST standard reference material 2709 (San Joaquin Soil).Öğe Pyridine containing chiral macrocycles: synthesis and their enantiomeric recognition for amino acid derivatives(Pergamon-Elsevier Science Ltd, 2011) Deniz, Pinar; Turgut, Yilmaz; Togrul, Mahmut; Hosgoren, HalilFour novel C(2)-symmetric enantiomerically pure, chiral pyridine-18-crown-6 type macrocycles containing lipophilic chains at the stereogenic centers were prepared. The enantioselectivity of the new ligands toward the enantiomers of D-,L-amino acid methyl ester derivatives were also determined by (1)H NMR titration method. These novel macrocycles have been showed to be strong complexing agents for D- and L-amino acid methyl ester hydrochloride salts (with K(ass) up to 13590 M(-1) and Delta G(0) up to 23.3 kJ mol(-1) and selectivity ratio: 80:20) by (1)H NMR titration methods. These macrocyclic hosts exhibited enantioselective binding towards the D-enantiomer of valine methyl ester hydrochloride with K(D)/K(L), up to 5.08 in CDCl(3) with 0.25% CD(3)OD. (C) 2011 Elsevier Ltd. All rights reserved.Öğe A series of novel ?-hydroxyamide based catalysts for borane-mediated enantioselective reductions of prochiral ketones(Pergamon-Elsevier Science Ltd, 2016) Azizoglu, Murat; Erdogan, Asli; Arslan, Nevin; Turgut, Yilmaz; Hosgoren, Halil; Pirinccioglu, NecmettinThe enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand has received considerable attention. Hydroxylamine-based chiral ligands with amide and hydroxyl functions in the presence of other co-ordinating groups are highly effective in these asymmetric reductions. The current work presents a simple one step synthesis of a series of beta-hydroxyamide-based ligands from the reaction between 3-hydroxy-2-naphthoic acid and chiral amino alcohols and their applications as catalysts in asymmetric borane-mediated reductions of aromatic prochiral ketones in THE The reductions provided the corresponding secondary alcohols with up to 96% ee and in good to excellent yields (89-99%). OFF calculations at B3LYP/6-31+g(d) level offered theoretical models to account for the enantioselectivity imposed by the chiral ligands in the reductions of the ketones. (C) 2016 Elsevier Ltd. All rights reserved.Öğe The synthesis and formation of complexes between derivatives of chiral Aza-18-crown-6 ethers and chiral primary organic ammonium salts(Springer, 2006) Karakaplan, Mehmet; Turgut, Yilmaz; Aral, Tarik; Hosgoren, HalilChiral mono aza-18-crown-6 derivatives have been prepared in optically active form and high yield from amino alcohols via a cyclization reaction with tetraethylene glycol ditosylate. The enantiomeric recognition by these chiral aza-crown ethers between chiral primary ammonium perchlorate salts has been characterized by UV-Vis at 25 degrees C in chloroform.Öğe Synthesis of C2-Symmetric Chiral Amino Alcohols: Their Usage as Organocatalysts for Enantioselective Opening of Epoxide Ring(Taylor & Francis Inc, 2010) Turgut, Yilmaz; Aral, Tarik; Karakaplan, Mehmet; Deniz, Pinar; Hosgoren, HalilA series of -amino alcohols derivatives were synthesized from (R)-2-amino-1-butanol and (S)-1,2-propanediol, and they have been used as organocatalaysts in the racemic ring opening of epoxide in good yields with high enantiomeric excess (up to 97%).Öğe Synthesis of new diaza-18-crown-6 ethers derived from trans-(R,R)-1,2-diaminocyclohexane and investigation of their enantiomeric discrimination ability with amino acid ester salts(Pergamon-Elsevier Science Ltd, 2013) Karakaplan, Mehmet; Ak, Devran; Colak, Mehmet; Kocakaya, Safak Ozhan; Hosgoren, Halil; Pirinccioglu, NecmettinThe synthesis of four diaza-18-crown-6 ethers with C-2-symmetry derived from trans-(R,R)-1,2-diaminocyclohexane bearing methyl, phenyl and phenoxymethyl moeities attached to a stereogenic centre on the crown ring were achieved. Enantiomeric discrimination of these macrocycles against amino acid methyl ester salts was examined by H-1 NMR titration method. They exhibit strong binding ability and some of them show a very high enantioselectivity towards amino acid esters, corresponding to 537 kJ/mol of binding energy difference in CDCl3 at 25 degrees C. Computational modelling showed parallel results with experimental calculations, thus providing a detailed understanding of molecular recognition mode and binding sites between the hosts and the guests. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Synthesis of novel C2-symmetric chiral crown ethers and investigation of their enantiomeric recognition properties(Pergamon-Elsevier Science Ltd, 2009) Turgut, Yilmaz; Aral, Tarik; Hosgoren, HalilA series of new C-2-symmetric chiral aza crown ether macrocycles 1-4 have been synthesized from (S)-3-aryloxy-1,2-propanediol and (S)-1,2-propanediol for the enantiomeric recognition of amino acid ester derivatives. These new macrocycles have been shown to be strong complexing agents for primary organic ammonium salts (with K up to 176.93 M-1 and Delta G degrees up to 12.81 kJ mol(-1)) by H-1 NMR titration. These macrocyclic host exhibited enantioselective bonding toward the D-enantiomer of phenylalanine methyl ester hydrochloride with K-D/K-L up to 6.87 in CDCl3 with 0.25% CD3OD. (C) 2009 Elsevier Ltd. All rights reserved.
