6 research outputs found
Aerobik C-H aktivasyonu için çift metalli hidroksit katalizörler
No full textCataloged from PDF version of article.Includes bibliographical references (leaves 60-70).The increasing interest in the oxidation of sp3 C-H and O-H bonds has garnered tremendous attention due to its potential for facile production of oxygenated organics. Precious metal-free bimetallic hydroxide-based materials are commonly employed in various applications such as batteries and photocatalysts. However, their prospects in C-H activation reactions have been poorly explored. This research focuses on the development and evaluation of a bimetallic Fe-Mn hydroxide catalyst for aerobic C-H activation and O-H oxidation reactions without the need for an initiator. The Fe-Mn hydroxide catalyst was synthesized and carefully optimized to enhance its catalytic efficiency in the direct oxygenation of a wide scope of alkylarene compounds through C-H functionalization and oxidation of benzylic alcohols. A series of Fe-Mn bimetal hydroxides with different Fe/Mn ratios were synthesized using a customized chemical co-precipitation method. These catalysts were then tested for the catalytic oxidation of fluorene to fluorenone using molecular oxygen as the sole oxidant, with the Fe0.6Mn0.4(OH)y-12S catalyst demonstrating the best performance. Under mild reaction conditions, the catalyst exhibited remarkable performance in activating C-H bonds using molecular oxygen as the oxidant. Various substrates, including alkylarenes and alcohols, were investigated, consistently yielding high yields of oxygenated products with minimal catalyst loadings. XRD, XPS, XANES, ICP-MS, BET, and TGA were employed to gain insights into the structural features of the catalyst. Our findings indicate that the following structural properties of the optimized Fe0.6Mn0.4(OH)y-12S catalyst could be responsible for the currently observed enhanced catalytic reactivity: i) unique Mn oxidation state (ca. Mn2.6+), ii) Fe cationic sites containing a mixture of Fe2+ and Fe3+ species, where Fe3+ species are the dominating species, iii)realtively low specific surface area of 68 m2/g, iv) relatively disordered and defective crystal structure comprised of bimetallic hydroxides as well as additional oxide/oxyhydroxide phases, v) residual Na+ surface species enabling electronic promotion of the cationic active sites via electron donation.by Beyzanur Erdiva
Gültekin Yazgan’ın hayatı ve Türkiye’de Görme Engelliler Kütüphaneciliği
No full textAnkara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2017.This work is a student project of the The Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.by Öztürk, Mert İbrahim
The rewiew of Tatar writer Tufan Minnullin's plays (In the example of "Eldirmişten Elmender", "Eniler ve Bebiler")
No full textBu tez çalışmasının amacı Tufan Minnullin'in "Eldirmişten Elmender", "Eniler ve Bebiler" adlı piyeslerinin incelenmesidir. Tufan Minnullin Tatar edebiyatının önde gelen sanatçılarından biridir. Tatar edebiyatına piyesleri ve farklı tarzda yazdığı eserleri ile katkıda bulunmuştur. Sanatçının piyeslerini incelemeden önce "1960-1990'lı Yıllarda Tatar Edebiyatı", "1960-1990'lı Yıllarda Dram Eserleri" ve "1990'lı Yıllardan Bugüne Tatar Edebiyatı" hakkında bilgiler verilecektir. Devamında "Tufan Minnullin'in Hayatı" ve "Tufan Minnullin'in Eserleri" ele alınacaktır. Sonraki bölümde bahsedilen piyeslerin incelemesi yapılacaktır. Son bölümde ise "Eniler ve Bebiler" adlı piyesin Türkiye Türkçesine çevrilmiş hali verilecektir. Tatar edebiyatında oldukça önemli bir yere sahip olan Tufan Minnullin hakkında ülkemizde yapılan çalışma sayısı oldukça azdır. Coğrafi olarak bakıldığında da Tataristan Türkiye'ye oldukça uzak bir ülkedir. Bu yüzden edebiyat alanında etkileşim istenilen düzeyde yaşanamamıştır. Tatar halkının yaşamını, kültürünü belirlediği çeşitli konular ile renklendirip tiyatro eserlerinde işleyen yazarı, seçilen piyesler ile tanıtmak amaçlanmıştır.The purpose of this thesis study is to examine Tufan Minnullin's plays "Eldirmişten Elmender", "Eniler and Bebiler". Tufan Minnullin is one of the leading artists of Tatar literature. He contributed to Tatar literature with his plays and works written in different styles. Information about "Tatar Literature in the 1965s and 1990s", "Drama Works in the 1965s and 1990s" and "Tatar Literature from the 1990s to Today" will be given before examining the artist's works. In the sequel" "The Life of Tufan Minnullin" and "The Works of Tufan Minnullin" will be discussed. An examination of the plays mentioned in the next section will be made. In the last section, the translated version of the play "Eniler and Bebiler" will be given to Turkish. The number of studies conducted in our country about Tufan Minnullin, who has a very important place in Tatar literature, is quite small. From a geographical point of view, Tatarstan is a country quite far from Turkey. For this reason, the desired level of interaction in the field of literature could not be experienced. It is aimed to introduce the author, who colors the life and culture of the Tatar people with various topics that he determines and works in theatrical works, with selected plays
Na-promoted bimetallic hydroxide nanoparticles for aerobic c-h activation catalyst design principles and insights into reaction mechanism
No full textA precious metal-free bimetallic Fe x Mn1-x (OH) y hydroxide catalyst was developed that is capable of catalyzing aerobic C-H oxidation reactions at low temperatures, without the need for an initiator, relying sustainably on molecular oxygen. Through a systematic synthetic effort, we scanned a wide nanoparticle synthesis parameter space to lay out a detailed set of catalyst design principles unraveling how the Fe/Mn cation ratio, NaOH(aq) concentration used in the synthesis, catalyst washing procedures, extent of residual Na+ promoters on the catalyst surface, reaction temperature, and catalyst loading influence catalytic C-H activation performance as a function of the electronic, surface chemical, and crystal structure of Fe x Mn1-x (OH) y bimetallic hydroxide nanostructures. Our comprehensive XRD, XPS, BET, ICP-MS, 1H NMR, and XANES structural/product characterization results as well as mechanistic kinetic isotope effect (KIE) studies provided the following valuable insights into the molecular level origins of the catalytic performance of the bimetallic Fe x Mn1-x (OH) y hydroxide nanostructures: (i) catalytic reactivity is due to the coexistence and synergistic operation of Fe3+ and Mn3+ cationic sites (with minor contributions from Fe2+ and Mn2+ sites) on the catalyst surface, where in the absence of one of these synergistic sites (i.e., in the presence of monometallic hydroxides), catalytic activity almost entirely vanishes, (ii) residual Na+ species on the catalyst surface act as efficient electronic promoters by increasing the electron density on the Fe3+ and Mn3+ cationic sites, which in turn, presumably enhance the electrophilic adsorption of organic reactants and strengthen the interaction between molecular oxygen and the catalyst surface, (iii) in the fluorene oxidation reaction the step dictating the reaction rate likely involved the breaking of a C-H bond (k H /k D = 2.4), (iv) reactivity patterns of a variety of alkylarene substrates indicate that the C-H bond cleavage follows a stepwise PT-ET (proton transfer-electron transfer) pathway
Two-Dimensional Bimetallic Hydroxide Nanostructures for Catalyzing Low-Temperature Aerobic CH Bond Activation in Alkylarene and Alcohol Partial Oxidation
No full textTwo-dimensional (2D) bimetallic NixMn1–x(OH)y layered double hydroxide (LDH) nanostructures were synthesized and optimized as a remarkably active catalytic platform for low-temperature aerobic C–H bond activation in alkylarenes and partial oxidation of alcohols using a wide substrate (i.e., reactant) and diverse solvent scope. The NixMn1–x(OH)y structure consists of nonprecious and earth-abundant metals that can effectively operate at low catalyst loadings, requiring only molecular oxygen as the stoichiometric oxidant. Structurally diverse alkylarenes as well as primary and secondary alcohols were shown to be competent substrates where oxidation products were obtained in excellent yields (93–99%). Comprehensive catalyst structural characterization via XRD, ATR-IR, TEM, EDX, XPS, BET, and TGA indicated that the ultimately optimized Ni0.6Mn0.4(OH)y-9S catalyst possessed not only particular rotational faults in its β-Ni0.6Mn0.4(OH)y domains but also distinct α/β-Ni0.6Mn0.4(OH)y interstratification disorders, in addition to a relatively high specific surface area of 125 m2/g, a 2D platelet morphology, and an average Mn oxidation state of +3.5, suggesting the presence of both Mn3+ and Mn4+ species in its structure working in a synergistic fashion with the Ni2+/x+ cations (the latter is justified by the lack of catalytic activity in the monometallic LDH catalysts Ni(OH)2 and Mn(OH)2). Kinetic isotope effect studies carried out in the fluorene oxidation reaction (kH/kD = 5.7) revealed that the rate-determining step of the catalytic oxidation reaction directly involved the scission of a C–H bond. Moreover, the optimized catalyst was demonstrated to be reusable through the application of a regeneration protocol, which can redeem the full initial activity of the carbon-poisoned spent catalyst in the fluorene oxidation reaction
Two-Dimensional Bimetallic Hydroxide Nanostructures for Catalyzing Low-Temperature Aerobic C–H Bond Activation in Alkylarene and Alcohol Partial Oxidation
No full textTwo-dimensional (2D)
bimetallic NixMn1–x(OH)y layered double
hydroxide (LDH) nanostructures were synthesized
and optimized as a remarkably active catalytic platform for low-temperature
aerobic C–H bond activation in alkylarenes and partial oxidation
of alcohols using a wide substrate (i.e., reactant)
and diverse solvent scope. The NixMn1–x(OH)y structure consists
of nonprecious and earth-abundant metals that can effectively operate
at low catalyst loadings, requiring only molecular oxygen as the stoichiometric
oxidant. Structurally diverse alkylarenes as well as primary and secondary
alcohols were shown to be competent substrates where oxidation products
were obtained in excellent yields (93–99%). Comprehensive catalyst
structural characterization via XRD, ATR-IR, TEM, EDX, XPS, BET, and
TGA indicated that the ultimately optimized Ni0.6Mn0.4(OH)y-9S catalyst
possessed not only particular rotational faults in its β-Ni0.6Mn0.4(OH)y domains but also distinct α/β-Ni0.6Mn0.4(OH)y interstratification
disorders, in addition to a relatively high specific surface area
of 125 m2/g, a 2D platelet morphology, and an average Mn
oxidation state of +3.5, suggesting the presence of both Mn3+ and Mn4+ species in its structure working in a synergistic
fashion with the Ni2+/x+ cations (the
latter is justified by the lack of catalytic activity in the monometallic
LDH catalysts Ni(OH)2 and Mn(OH)2). Kinetic
isotope effect studies carried out in the fluorene oxidation reaction
(kH/kD = 5.7)
revealed that the rate-determining step of the catalytic oxidation
reaction directly involved the scission of a C–H bond. Moreover,
the optimized catalyst was demonstrated to be reusable through the
application of a regeneration protocol, which can redeem the full
initial activity of the carbon-poisoned spent catalyst in the fluorene
oxidation reaction
