Chemistry / Kimya
Permanent URI for this collectionhttps://hdl.handle.net/11147/4072
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Research Project Paladyum N-heterokarben kompleksleri içeren zeolitlerin Heck ve Suzuki tepkimelerinde katalizör olarak kullanılması(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2006) Artok, Levent; Aksın, Özge; Bulut, Hatice; Durgun, GülaySilika bağlı Pd-N-heterosiklik karben kompleksleri ve paladyum yüklü silika bağlı imidazolinyum tuzlan bromoarenlerin Mizoroki-Heck tepkimelerinde yüksek aktivite göstermiştir. Tepkimeler liganddan ayrılan Pd tarafından katalizlenmiştir. Tepkime sonunda Pd silika yüzeyine çökelerek tekrar kazanılmıştır. Pd yüklü NaY zeolit bromoarenlerin Suzuki tepkimelerinde yüksek TOF aktivitesi göstermiştir. Katalizörün aktiflik göstermesi için ortamda suyun bulunması elzemdir. Katalizör kloroarenler için de aktivite göstermiştir. Ancak tepkime ortamında suyun bulunması katalizör aktivitesine olumsuz etki göstermiştir.Research Project Paladyum ve rodyum katalizli tandem karbonilatif kenetlenme tepkimeleri(2008) Artok, Levent; Aksın Artok, Özge; Kuş, Melih; Dege, Nurcan Fatma; Özkılınç, Yelda Fatma[No Abstract Available]Article Citation - WoS: 4Citation - Scopus: 6The Effect of Additives on Hydrodesulfurization of Dibenzothiophene Over Bulk Molybdenum Sulfide: Increased Catalytic Activity in the Presence of Phenol(Elsevier Ltd., 2008) Gül, Ömer; Atanur, Osman M.; Artok, Levent; Erbatur, OktayThe effect of various additive organic reagents on the activation of MoS3 as molybdenum sulfide catalyst precursor during hydrodesulfurization reaction of dibenzothiophene was studied. It was found that the presence of phenol or 1-naphthol greatly promoted the activity of the catalyst, while tetralin, 9,10-dihydrophenanthrene, ethylbenzene, and pyridine reagents were found to be detrimental for the activity of the catalyst.Article Citation - WoS: 11Citation - Scopus: 2Synthesis of Α,β-Unsaturated Ketones by Rhodium-Catalyzed Carbonylative Arylation of Internal Alkynes With Arylboronic Acids(Georg Thieme Verlag, 2008) Kuş, Melih; Aksın Artok, Özge; Ziyanak, Fırat; Artok, LeventThe Rh-catalyzed reaction of arylboronic acids with internal alkynes under a CO atmosphere in the presence of an acid additive afforded α,β-unsaturated ketones as the major products. Hydroacylation of internal alkynes, except in the case of diaryl acetylenes, proceeded in syn fashion, yielding the E-configured isomer. A mixture of E- and Z-isomers was obtained with diphenyl acetylene. Reactions were also highly regioselective for various nonsymmetric alkynes.Article Citation - WoS: 27Citation - Scopus: 30Rhodium Catalyzed Reaction of Internal Alkynes With Organoborons Under Co Atmosphere: a Product Tunable Reaction(Elsevier Ltd., 2009) Artok, Levent; Kuş, Melih; Aksın, Özge; Dege, Fatma Nurcan; Özkılınç, Fatma YeldaAlkynes react with organoborons under a CO atmosphere in the presence of a rhodium(I) catalyst to afford mainly 5-aryl-2(5H)-furanones, α,β-unsaturated ketones, and indanones. The product selectivity can be tuned by modifying the reaction conditions.Article Citation - WoS: 167Citation - Scopus: 197Preparation and Characterization of Activated Carbons by One-Step Steam Pyrolysis/Activation From Apricot Stones(Elsevier Ltd., 2006) Şentorun-Shalaby, Çiğdem; Uçak Astarlıoğlu, Mine G.; Artok, Levent; Sarıcı, ÇiğdemThe activated carbons were prepared from Malatya (a city located in the south-east of Turkey) apricot stones by one-step steam pyrolysis/activation process and characterized for their pore structures. Three kinds of apricot stones that differ in their sulfur content, because of the different drying processes, were chosen for this study to investigate the effect of sulfur in the activated carbon production. The effect of process variables, such as activation temperature, soak time, and particle size range was studied on these samples. The activation temperature and time tested were in the ranges of 650-850 °C for 1-4 h. The activated carbons were evaluated for their chemical (elemental composition), surface (BET surface area, mercury porosimetry), and adsorption (iodine number) properties. Carbonization behavior of the apricot stones was investigated by thermogravimetric analysis. Scanning electron microscopy (SEM) was used to follow the changes in the carbon texture upon activation. The experimental results revealed that carbons obtained by the same conditions of activation show differences in their pore structures and adsorption characteristics due to their sulfur contents. The highest BET surface area carbon (1092 m2/g) was obtained from the low sulfur content (0.04%) apricot stone with a particle size range of 1-3.35 mm at the activation conditions of 800 °C for 4 h. The experimental results showed that commercial production of porous activated carbons from Malatya apricot stones is feasible in Turkey.Article Citation - WoS: 25Citation - Scopus: 20Rhodium-Catalyzed Carbonylative Arylation of Alkynes With Arylboronic Acids: an Efficient and Straightforward Method in the Synthesis of 5-Aryl(Royal Society of Chemistry, 2006) Aksın, Özge; Dege, Nurcan; Artok, Levent; Türkmen, Hayati; Çetinkaya, Bekir5-Aryl-2(5H)-furanones can be synthesized by the Rh-catalyzed reactions of arylboronic acids with internal alkynes under a CO atmosphere.Article Citation - WoS: 85Citation - Scopus: 88Effect of Immobilization on Catalytic Characteristics of Saturated Pd-N Carbenes in Mizoroki-Heck Reactions(Elsevier Ltd., 2006) Aksın, Özge; Türkmen, Hayati; Artok, Levent; Çetinkaya, Bekir; Ni, Chaoying; Büyükgüngör, Orhan; Özkal, ErhanA saturated Pd-N-heterocyclic complex was immobilized on an amorphous silica. The complex itself is of very high thermal stability. However, TEM observations, hot filtration, reusability, and poisoning tests all revealed that the complex acted only as a precatalyst to highly active Pd species in Mizoroki-Heck reactions when immobilized. The complex appears more stable when used under homogeneous reaction conditions. The immobilized complex afforded high turnover numbers, 104-105. The higher turnover frequencies were realized at the lower Pd concentrations, which is a characteristic property of ligand-free Pd catalyzed reactions.Article Citation - WoS: 45Citation - Scopus: 48Pd-Loaded Nay Zeolite as a Highly Active Catalyst for Ligandless Suzuki-Miyaura Reactions of Aryl Halides at Low Pd Loadings Under Aerobic Conditions(Elsevier Ltd., 2007) Durgun, Gülay; Aksın, Özge; Artok, LeventThe Pd(NH3)42+-loaded NaY zeolite was found to be a highly active catalyst precursor for Suzuki-Miyaura (SM) reactions of aryl bromides and aryl chlorides at low Pd concentrations in air. Aryl bromides and arylboronic acids can couple effectively both in pure water and in N,N-dimethylacetamide/water mixtures (1/1) within minutes with turnover frequencies (TOF) up to 4 × 105 h-1. The presence of a minute amount of water was crucial for the success of the reaction with chloroarenes. The excess amounts of as-received zeolite provided the necessary water for the reaction. The results suggest that the combined use of the water-zeolite system may have a synergistic effect in the reaction.Article Citation - WoS: 36Citation - Scopus: 40The Kinetics of Citral Hydrogenation Over Pd Supported on Clinoptilolite Rich Natural Zeolite(Elsevier Ltd., 2005) Yılmaz, Selahattin; Uçar, Şule; Artok, Levent; Güleç, HilalThe liquid phase hydrogenation of citral has been investigated over Pd (2.42%) supported on clinoptilolite rich natural zeolite catalyst for different reaction conditions. The zeolite support did not affect the active metal properties. This was attributed to the large size of Pd particles on the support. High selectivity (90%) to citronellal was obtained at complete conversion of citral. The catalytic activity increased with reaction temperature (80, 100, 120°C) following an Arrhenius behaviour, while selectivity remained constant for a given conversion. Selectivity to citronellal increased from 78 to 90% with increase in the amount of catalyst in the reaction solution (Citral/Pd mole ratio 293, 176 and 105). The spent catalyst regained its fresh activity and selectivity upon regeneration.