Bibliographies thématiques / Metal-free oxidation

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Littérature scientifique sur le sujet « Metal-free oxidation »

Auteur : Grafiati
Publié le 9 mars 2023
Mis à jour le 10 mars 2023

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Articles de revues sur le sujet "Metal-free oxidation"

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Wang, Xi, et Yingwei Li. « Nanoporous carbons derived from MOFs as metal-free catalysts for selective aerobic oxidations ». Journal of Materials Chemistry A 4, no 14 (2016) : 5247–57. http://dx.doi.org/10.1039/c6ta00324a.

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A new kind of metal-free catalyst comprised of highly graphitized N-doped nanoporous carbons from direct carbonization of metal–organic frameworks (MOFs) turns out to be an excellent metal-free catalyst for a series of liquid-phase oxidation reactions including aerobic oxidations of cyclohexane and toluene as well as oxidative coupling of amines.
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Zhao, Rong, Denghu Chang et Lei Shi. « Recent Advances in Cyclic Diacyl Peroxides : Reactivity and Selectivity Enhancement Brought by the Cyclic Structure ». Synthesis 49, no 15 (12 juin 2017) : 3357–65. http://dx.doi.org/10.1055/s-0036-1588458.

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Preliminarily studies on cyclic diacyl peroxides have shown novel and superior reactivities compared with their acyclic diacyl peroxide counterparts in many reaction types. After summarizing the methods available for the preparation of cyclic diacyl peroxides and describing their structural features, this review brings together an overview of their reactivities with respect to oxidations and decarboxylations, and demonstrates the advantages of reactions with cyclic diacyl peroxides, which include metal-free, additive-free, milder conditions, higher yields and better selectivities.1 Introduction2 Methods of Preparation of Cyclic Diacyl Peroxides3 Structures and Stabilities of Cyclic Diacyl Peroxides4 Oxidation Reactions4.1 Oxidative Additions to Alkenes4.2 Oxidation Reactions of Heteroatoms4.3 Oxidation Reactions of 1,3-Dicarbonyl Compounds4.4 Hydroxylations of Arenes5 Decarboxylations6 Conclusion
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Duan, Xiaoguang, Hongqi Sun et Shaobin Wang. « Metal-Free Carbocatalysis in Advanced Oxidation Reactions ». Accounts of Chemical Research 51, no 3 (mars 2018) : 678–87. http://dx.doi.org/10.1021/acs.accounts.7b00535.

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Dos Santos, Aurélie, Laurent El Kaïm et Laurence Grimaud. « Metal-free aerobic oxidation of benzazole derivatives ». Organic & ; Biomolecular Chemistry 11, no 20 (2013) : 3282. http://dx.doi.org/10.1039/c3ob27404g.

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Lou, Ji-Cong, Jian-Ye Li, Wen-Wu Sun et Bin Wu. « Metal-Free Oxidation of Trichloroacetimidates to Aldehydes ». Asian Journal of Organic Chemistry 8, no 2 (18 janvier 2019) : 265–68. http://dx.doi.org/10.1002/ajoc.201800683.

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Biswas, Swapan Kumar, et Titas Biswas. « Metal-free one-pot oxidative conversion : Molecular Iodine Mediated Oxidation Organic Reactions ». International Journal of Experimental Research and Review 27 (30 avril 2022) : 45–52. http://dx.doi.org/10.52756/ijerr.2022.v27.005.

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Various oxidative compounds such as aldehyde, ketone ester, and acids can be produced in large yields by an effective iodine-mediated oxidative reaction of organic molecules. Molecular iodine is a generally available and commercially extremely inexpensive substance that induces oxidative esterification. With the comparison with different Brønsted acid catalysis, molecular iodine or iodophilic activations proceed the reaction onto a deoxygenation pathway. With only a few mol% of I2, the oxidation occurs very quickly at room temperature. This approach could also be used to transport different benzil derivatives from nonactivated alkynes, such as diaryl acetylenes. Molecular iodine with several mild reagents such as aq. NH3, ∼30% aq. H2O2 and DMSO might be used to convert various one degree alcohols, particularly benzylic alcohols, into the corresponding aromatic amides in suffiently high yields in a one-pot method. Similarly, by treating different benzylic chloride, bromide and iodide with a molecular iodine oxidation medium, the corresponding aromatic amides may be prepared in a one-pot method. The reactions in this section include transformation of several compounds into their respective oxidative products with the metal-free one-pot oxidative.
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Uyanik, Muhammet, Dai Nagata et Kazuaki Ishihara. « Hypoiodite-catalysed oxidative homocoupling of arenols and tandem oxidation/cross-coupling of hydroquinones with arenes ». Chemical Communications 57, no 88 (2021) : 11625–28. http://dx.doi.org/10.1039/d1cc05171g.

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Hamami, Zine Eddine, Laurent Vanoye, Pascal Fongarland, Claude de Bellefon et Alain Favre-Reguillon. « Metal-free, visible light-promoted aerobic aldehydes oxidation ». Journal of Flow Chemistry 6, no 3 (septembre 2016) : 206–10. http://dx.doi.org/10.1556/1846.2016.00023.

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Rahimi, Alireza, Ali Azarpira, Hoon Kim, John Ralph et Shannon S. Stahl. « Chemoselective Metal-Free Aerobic Alcohol Oxidation in Lignin ». Journal of the American Chemical Society 135, no 17 (19 avril 2013) : 6415–18. http://dx.doi.org/10.1021/ja401793n.

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Wu, Xiao-Feng, Andranik Petrosyan, Tariel V. Ghochikyan, Ashot S. Saghyan et Peter Langer. « Metal-free oxidation of benzyl amines to imines ». Tetrahedron Letters 54, no 24 (juin 2013) : 3158–59. http://dx.doi.org/10.1016/j.tetlet.2013.04.018.

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Thèses sur le sujet "Metal-free oxidation"

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Schilling, Waldemar [Verfasser]. « Approaches for Transition Metal-Free Photocatalytic Oxidation Reactions / Waldemar Schilling ». Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/1233009001/34.

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Crites, Charles-Oneil. « Investigating the Interactions between Free Radicals and Supported Noble Metal Nanoparticles in Oxidation Reactions ». Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33404.

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This thesis studies the interaction between free radical species and supported noble metal nanoparticles (silver and gold) in the context of oxidation reactions. The peroxidation of cumene is the first reaction to be discussed and the difference in peroxidation product distribution using silver nanoparticles (AgNP) versus gold nanoparticles (AuNP) is examined. Specifically, cumyl alcohol is obtained as the major product obtained when using supported AuNP, whereas cumene hydroperoxide is favoured for AgNP. Such variations in product distribution are partially explained by the differences in the nanoparticle Fenton activity, where the TiO2 support was proposed to enhance such activity due to possible electron shuttling capabilities with the nanoparticle surface. Use of hydrotalcite as a support was found to minimize this characteristic, due to its insulator properties. The stability of hydroperoxide was tested in the presence of various others supports (activated carbon, Al2O3, ZnO, SiO2 and clays) with little success, with hydroperoxide exhibiting stability in the presence of HT. Using an oxygen uptake apparatus, the interaction of the cumyl peroxyl radical with the AuNP surface was demonstrated. Furthermore, this interaction promotes decomposition leading to the corresponding alkoxyl radical and subsequent hydrogen abstraction to form the observed cumyl alcohol product. The radical interaction with supported nanoparticles, and its reversibility appear different for gold and silver and accounts for a large part of the product distribution differences observed between AuNP and AgNP, as illustrated below. The peroxidation of ethylbenzene and propylbenzene was studied and revealed the participation of a reactive surface oxygen species due to the decomposition of peroxyl radicals on the nanoparticle surface. The reactive oxygen species was found to be transient in nature in the case of AuNP . Furthermore, this surface species was found to be an important participant in hydrogen abstraction leading to peroxide product formation. Finally, supported nanoparticle catalyzed tetralin peroxidation was investigated to determine the influence of temperature on the peroxidation product distribution and how changes in the reaction temperature can effect the radical-nanoparticle surface interactions.
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Duong-Viet, Cuong. « Synthesis and processing of nitrogen-doped carbon nanotubes as metal-free catalyst for H2S selective oxidation process ». Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF029/document.

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Les nanotubes de carbone (NTCs) dopés avec différents hétéroéléments tels que l'oxygène et l'azote connaissent un intérêt croissant dans le domaine de la catalyse hétérogène comme leur utilisation en tant que catalyseur sans métaux. L'objectif de cette thèse consiste à la synthèse et la caractérisation de matériaux catalytiques à base de NTC dopés à l'azote supportés sur du carbure de silicium SiC par voie in situ (CVD) et ex-situ méthodes. Une autre approche a été utilisée pour la fonctionnalisation de la surface des nanotubes de carbone et basées sur l'utilisation d'un agent oxydant (HNO3) en phase gazeuse. Ce procédé d'oxydation crée non seulement des défauts sur la surface des nanotubes de carbone mais également décore leur surface avec des groupes fonctionnels oxygénés. Les NTCs dopés à l'oxygène et à l'azote ainsi synthétisés ont été caractérisés par différentes techniques (XPS, MEB, MET, BET, ATG). Ces catalyseurs carbonés présentent des performances remarquables en termes d'activité et de sélectivité en soufre, et une très grande stabilité sous flux en fonction du temps dans la réaction d'oxydation partielle de l'H2S en soufre élémentaire, et ce, même à vitesse spatiale de gaz élevée (WHSV) et faible rapport O2/H2S. L'influence des différentes propriétés physico-chimiques et les défauts présents sur la surface des NTC sur les performances catalytiques ont été étudiée et discutée dans le cadre de ce travail
Carbon nanotubes (CNTs) containing different doping such as oxygen and nitrogen composites have received more and more scientific attention as metal-free catalyst in the field of heterogeneous catalysis. The aim of this thesis is related to the synthesis and characterization of nitrogen-doped CNTs decorated on SiC support using both in-situ (CVD with NH3) and ex-situ (N@C) methods. Other approach was employed for the surface functionalization of CNTs is based on the use of oxidative agent (HNO3) in gas phase. This oxidation process not only creates defects on the CNTs surface but also decorates their surface with oxygenated functional groups. The as-synthesized oxygen- and nitrogen-doped CNTs are characterized by different techniques (XPS, SEM, TEM, BET, TGA). The carbon based catalysts exhibit outstanding performances in term of activity and sulfur selectivity, and very high stability with time on stream in the partial oxidation of H2S into elemental sulfur even at high gas space velocity (WHSV) and low O2-to-H2S molar ratio. The influence of the physical-chemical properties and defects present on the CNTs surface on the catalytic performance was thoroughly investigated and discussed within the framework of this work
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Yang, Weilu. « Electrochemical advanced oxidation processes for emerging organic contaminants removal with graphene-based modified carbon felt electrode ». Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2025.

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Grâce au développement continu de technologies d'analyse environnementale, certains produits chimiques, qui sont reconnus être nocif, ont récemment attiré l'attention, puisqu'ils constituent un menace pour l'environnement et la santé publique.Parmi ces polluants émergent, les produits pharmaceutiques et de soins personnels (PPSP)sont devenus le cibles dela recherche internationale. La chine est le plus grand producteur et le marché des médicaments dans le monde. Avec le développement de l'économie sociale et l'amélioration du niveau de vie de la population, de la production et de l'utilisation de divers PPSP présents en chine augmente rapidement. Par comparaison avec les polluants classiques, ces contaminants émergents sont généralement difficiles à analyser en raison de la limitation de technologies analytiques et de sa faible concentration dans les eaux naturelles.Les usines traditionnelles de traitement des eaux usées ne peuvent pas éliminer efficacement ces produits. La recherche sur l'évaluation des risques et le contrôle des nouveaux contaminants émergents, en chine constitue actuellement un grand défi. Il est donc essentiel de renforcer la recherche sur l'évaluation des risques pour l'environnement et les technologies de traitement efficaces pour éliminer ces polluants émergents. Les procédés d'oxydation avancée (POA) constituent une technologie de traitement efficace et ont été largement utilisés dans le traitement des polluants organiques réfractaires tels que les la destruction des contaminants émergents en milieu aqueux à cause de leur forte pouvoir d'oxydation permettant une minéralisation in situ des polluants. Le graphite, comme un nouveau type de matériau carbone adsorbant, est devenue un matériau d'électrode pour le traitement de la pollution due à son excellente conductivité et surface spécifique très élevée. Toutefois, son application dans les AOPs n'a pas été largement étudié et le mécanisme d'oxydation n'a pas été expliquée de manière systématique. Par conséquent, ce travail présent une étude détaillée sur le rôle des électrodes graphite modifiées dans les procédés électrochimiques d'oxydation avancée (PEOA) avec la préparation électrochimique des électrodes modifiées au graphène par exfoliation, et leur application dans le PEOA "électro-Fenton" (EF) pour le traitement des contaminants émergents. Ainsi le cathode en feutre de carbone modifiée au graphène a permis de d'éliminer différents contaminants émergents sans utilisation d'ions ferreux (catalyseur du procédé électro-Fenton) car les radicaux hydroxyles sont générés à travers d'un procédure catalytique grâce à la dopage du graphène à l'azote. Ensuite les cinétiques de dégradation et de minéralisation ainsi que les mécanismes d'oxydation de différents contaminants émergents ont été explorées
In recent years, with the continuous development of environmental analysis technologies, some chemicals, which have long been recognized but recently attracted attention, have been continuously entering the environment and threatening human health and ecological environment. The emergence of these new pollutants have attracted wide attention. Among them, pharmaceuticals and personal care products (PPCPs) have become international research hotspots. China is the largest medicine producer and market in the world. With the development of social economy and the improvement of people's living standards, the production and use of various PPCPs in China are increasing rapidly. Compared with the traditional pollutants, the new emerging contaminants are generally difficult to be analyzed due to the limitation of analytical technologies and its low concentration in water. The traditional sewage treatment plants can not achieve efficient degradation and removal effects. The research on risk assessment and control of new emerging contaminants in China is still a big challenge. It is necessary to strengthen the research on potential environmental risk assessment and efficient treatment technology. Advanced oxidation processes (AOPs), as an efficient pollutant treatment technology, has been widely used in the treatment of refractory organic pollutants such as new emerging contaminants in water because of its strong oxidation ability, which can effectively degrade and mineralize pollutants in water. Graphene, as a new type of carbon material, has become an efficient adsorbent and catalyst for pollution treatment due to its excellent conductivity and high specific surface area. However, its application in AOPs has not been widely reported and its mechanism has not been systematically explained. Based on this, this paper studied the role of graphene modified electrodes in electrochemical advanced oxidation processes (EAOPs) with the preparation of graphene by electrochemical exfoliation, application of graphene modified electrodes to electrochemical Fenton (EF) process for the degradation of new emerging contaminants; the construction of in-situ iron-free EAOPs with cathodes modified with nitrogen-doped graphene for abatement of new emerging contaminants and the mechanism of highly efficient catalysis with nitrogen-doped graphene have been explored
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Zhang, Yu. « Visible Light-Mediated Metal-Free Photocatalytic Oxidative Reactions and Cycloadditions ». Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-14EF-8.

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SUAREZ, BERTOA RICARDO. « Sustainable procedures in organic synthesis ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2009. http://hdl.handle.net/10281/7474.

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O-acyl-N-benzyllactamides are obtained in good yield by reaction of 4-benzyl-5-methyl-1,3-oxazolidine-2,4-diones with Grignards reagents and with lithium alkyls. Three alkanes and two ethers were oxidised with ozone in dichloromethane solution or in aqueous pH 3 suspension. Cyclodecane and cyclododecane were converted into the corresponding cycloalkanones. n-decane was converted into a mixture of isomeric n-decanones and carboxylic acids. An ester was formed from the ethers. Hence, one of the methylene groups of these substrates is generally converted into a carbonyl group. Some of these reactions have preparative value. The oxidation of naphthalene in dichloromethane or acetonitrile with excess ozone gives phthalic aldehyde, 2-formyl benzoic acid and phthalic anhydride. Small amounts of the (E)- and (Z)-isomer of 3-phenyl-(2-formyl)-propenal and are also observed in some cases. The reaction is faster in acetonitrile than in dichloromethane owing to the higher solubility of ozone in the former solvent. The reaction is faster on lowering the temperature because of the increase of the concentration of ozone in solution at lower temperature. With a 1:1 or a 1:2 naphthalene:ozone ratio high conversion and low selectivity for the anhydride is observed. The ozonation of cyclohexane in dichloromethane or acetonitrile gives cycloxexanone, cyclohexanol and acidic material. The influence of solvent, reactant concentration, amount of ozone, temperature, reaction time is studied. A reaction mechanism is proposed based on the results of a simulation of the reaction energetics. The ozonation of N-phenylmorpholine in dichloromethane or acetonitrile produced a lactame and a diformylderivative. These products derive from the attack of ozone at the heterocyclic ring. The reaction mechanism has been investigated by DFT calculations which show that the reaction occurs through the insertion of ozone at the carbon-hydrogen bond of a methylenic group of the morpholine ring. The regioselectivity is due to the to the significantly lower energy barrier calculated for the attack of ozone in α to nitrogen than in α to oxygen. Also, the energy barrier decreases with increasing the polarity of the solvent, accounting for the higher reaction rate observed for the reaction carried out in acetonitrile than in dichloromethane. The ozonation of trans- and cis-decalin in dichloromethane or acetonitrile gives the corresponding 9-hydroxydecalinns, 2- and 3-decalones and acidic material. The influence of solvent, reactant concentration, amount of ozone, temperature, reaction time is studied. A reaction mechanism is proposed based on the results of a simulation of the reaction energetics. The N,N bis(salicylidene)ethylenediaminocobalt(II) catalysed oxidative carbonylation of para-substituted aromatic primary amines at 100 °C in methanol gives carbamates in high yields. In presence of excess dimethylamine also N-aryl-N’,N’-dimethylureas are formed. In methylene chloride moderate yields in isocyanate are obtained. 1-methylbenzylamine gives the carbamate and the urea in high yield. i-propylamine gives only the urea. An α-aminoalcohol gives a 1,3-oxazolidin-2-one. Aliphatic secondary amines react faster and give carbamates in methanol and ureas in methylene chloride. The turnover frequency is also measured in two cases.
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Duan, Xiaoguang. « Catalytic Oxidative Degradation of Hydrocarbons Using Novel Metal-Free Nanocarbon Catalysts ». Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/1951.

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This research presents novel nanocarbon materials as green and metal-free carbocatalysts for advanced oxidative processes toward environmental remediation. Various nanocarbons exhibit high catalytic activity in activation of sulfate oxidants for degradation of water contaminants. The tailored surface chemistry of nanocarbons and insightful mechanistic studies for catalytic activation of superoxides were revealed via deliberate materials design, advanced characterization techniques and theoretical calculations.The findings would significantly contribute to materials chemistry, environmental science, carbocatalysis and other related fields.
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Zhang, Yu [Verfasser]. « Visible Light-Mediated Metal-Free Photocatalytic Oxidative Reactions and Cycloadditions / Yu Zhang ». Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1221802372/34.

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Lamani, Manjunath. « Design And Development Of Synthetic Methods Using Metal-Mediated And Metal Free Redox Reactions : Novel C-H Activations, Reductions And Oxidative Transformations ». Thesis, 2012. http://hdl.handle.net/2005/2501.

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The thesis entitled “Design and Development of Synthetic Methods using Metal-mediated and Metal-free Redox Reactions: Novel C-H Activations, Reductions and Oxidative Transformations” is presented in 4 chapters Chapter 1; Iodine catalyzed amination of benzoxazoles: efficient metal free route to 2-aminobenzoxazoles under mild conditions. The Chapter 1 of this thesis describes iodine catalyzed C-H activation of benzoxazole with primary and secondary amines to form oxidative aminated products. Selective C-H oxidation is a frontline area of modern chemical research as it offers the opportunities to new avenues and more direct synthetic strategies for the synthesis of complex organic molecules.1 In this context, transition metals such as palladium copper, nickel etc, are used extensively for the functional group directed C-H activation, and thus provides new, rapid, low-cost, and environmentally benign protocols for the construction of new chemical bonds.2 During the past two decades iodine and hypervalent iodine have been focus of great attention as they provide mild, chemoselective and environmentally benign strategies in contrast to toxic metal oxidants.3 In this chapter, a facile metal-free route of oxidative amination of benzoxazole with secondary or primary amines in the presence of catalytic amount of iodine (5 mol%) in aq tert-butyl hydroperoxide (1equiv) and AcOH (1.1 equiv) at ambient temperature, under the solvent-free reaction condition is presented. This user-friendly method to form C-N bonds produces tert-butanol and water as the by-products, which are environmentally benign. A wide range of benzoxazole derivatives containing electron-donating and electron-withdrawing groups were coupled with both primary and secondary amines (Scheme 1). Application of this methodology is demonstrated by synthesizing therapeutically active benzoxazoles by reacting 5-chloro-7-methylbenzoxazole with N-methylpiperazine and N-ethylhomopiperazine to obtain corresponding N-aminatedbenzaxozoles, which exhibit antidiarrhetic activity (Scheme 2).4 Scheme 2 Chapter 2: NIS catalyzed reactions. amidation of acetophenones and oxidative amination of propiophenones Chapter 2 is divided in to 2 parts. Part 1 describes the synthesis of α-ketoamides by using acetophenone and secondary amine in the presence of N-iodosuccinamide and TBHP in acetonitrile at room temperature, whereas Part 2 reveals the synthesis of 2-aminoketones by reacting aryl alkyl ketones and suitable secondary amine in the presence of NIS and TBHP. Part 1: Oxidative amidation, synthesis of α-ketoamide: Alpha α-ketoamides are important intermediates in organic synthesis that are present in a variety of natural products, and pharmaceutically active compounds. Herein, a mild and efficient conversion of acetophenones to α-ketoamide is documented by using aq.TBHP and N-iodosuccinamide (NIS) as a catalyst, at ambient temperature. This amidation reaction was found to be versatile as several aetophenone derivitives containing electron-withdrawing and electron-donating substituents underwent a facile amidation. It was also found that acetyl derivatives of heterocylic compounds could be easily converted to their corresponding ketoamides (few examples are shown in Scheme 3).5 Scheme3 Part 2 of Chapter 2 narrates a novel amination of propiophenone and its derivatives catalysed by NIS in the presence of TBHP to furnish their corresponding 2-aminoketone derivatives (Scheme 4). These derivatives are ubiquitous scaffolds that are present in a wide variety of therapeutic agents. Some of these compounds are used in the treatment of depression, smoking cessation, as monoamine uptake inhibitors, rugs for cancer. They are photoinitiators, precursors to β-aminoalcohols, such as pseudoephedrine analogues. 2-Aminoacetophenone analogues are also important intermediates for the formation of several heterocyclic compounds and are active moieties in several important drugs such as ifenprodil, Scheme 4. Chapter 3: Efficient oxidation of primary azides to nitriles This Chapter is divided in to 2 parts, which presents the oxidation of primary azides to their corresponding nitriles. Part 1: An Efficient oxidation of primary azides catalyzed by copper iodide: a convenient method for the synthesis of nitriles In Part 1, an efficient oxidation of primary azides catalyzed by copper iodide to their corresponding nitriles is reported. Herein, the oxidation of primary azide to nitrile is performed using catalytic amount of copper iodide, and aq TBHP in water at 100 ° C. This methodology is compatible with a wide range of primary benzylic azides that contain electron-donating and electron-withdrawing functional groups. The oxidation was found to be selective and a number of oxidizable functional groups were well-tolerated during the reaction conditions (few examples are shown in Scheme 5).6 Scheme 6 Furthermore, oxidation of secondary azides furnished the corresponding ketones in excellent yields (Scheme 6).6 In the Part 2 of Chapter 3, a non-metal catalysed oxidation of primary azides to nitriles at ambient temperature is reported. This part reveals the oxidation of primary azides to nitriles by employing catalytic amounts of KI (25 mol%), DABCO (25 mol%) and aq. TBHP (3 equiv., 70% solution in water). This reaction provides a good selectivity, as double and triple bonds were not oxidized under the reaction conditions. Additionally, chemoselective oxidation of benzylicazides against aliphatic azides increases the potential application of the present method (Scheme 7).7 Chapter 4: Chemoeselective reduction of olefins Part 1: Iron chloride catalysed aerobic reduction of olefins using aqueous hydrazine at ambient temperature Chapter 4 describes the reduction olefins and acetylenes, which is presented in two Parts. Part 1 documents utility of hydrazine (1.5 equiv) for the chemoselective reduction of nonpolarised carbon-carbon bond using iron catalysts. In this part, a chemoselective reduction of alkenes and alkynes in the presence of a variety of reducible functional groups is demonstrated (Scheme 8). The highlight of the present method is that the reduction proceeds well at room temperature and requires only 1.5 equiv of hydrazine hydrate. The olefin reduction by hydrazine depends upon the controlled release of diimide during the reduction. Generally, metal catalyzed reduction of olefins employ a large excess of hydrazine (10-20 equiv), which might be attributed to uncontrolled release of diimide during the reduction.8 Scheme 8 Part 2: Guanidine catalyzed aerobic reduction: a selective aerobic hydrogenation of olefins using aqueous hydrazine In Chapter 4, part 2, organocatalytic generation of diimide and its utility to reduce the double bonds is presented. Generation of diimide in situ by using organo catalysts and its use for the reduction of carbon-carbon double bond is one of the interesting topics in organic chemistry. It has been shown in this part of the thesis that the reduction of olefin at room temperature can be efficiently performed by using 10 mol% of guanidine nitrate, 2 equiv of aqueous hydrazine in oxygen atmosphere. This method tolerates a variety of reducible functional groups such as nitro, azido, and bromo and protective groups such as methyl ethers, benzyl ethers, and Cbz groups. It is also shown that terminal olefin can be selectively reduced in the presence of internal olefin (Scheme 9). Unlike other methods that employ diimide strategy, the present method is shown to be efficient in reducing substrates those contain internal double bonds such as cinnamyl alcohol and its derivatives
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Kao, Wei-Huan, et 高偉桓. « Density functional theory calculations on boron-doped carbon nanotubes as a potential metal-free catalyst for CO oxidation ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/vqv3zc.

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碩士
中原大學
化學研究所
106
By means of density functional theory (DFT) calculation, we used the carbon nanotubes with different content of doped boron as potential metal-free catalysts for the CO oxidation. In order to find the possible active sites for CO oxidation, we investigated the O2 -adsorption behavior on different position of 1 and 2 B-doped carbon nanotubes and find the most stable structures of adsorbed O2 are flat on C-B site of both nanotubes with the adsorption energies of -0.85 and -1.29 eV, respectively. Then we investigated the catalytic reaction paths of CO oxidation, divided into two parts: (1) CO + O2* → CO2 + O*, where the activation energy required for B-doped and BB-doped catalysts are 0.34 eV and 0.42 eV, respectively; (2) O* + CO → CO2: the activation energy required for BB-doped is 0.14 eV. The reaction is through the Eley-Rideal mechanism (ER) to produce carbon dioxide. After two CO oxidation processes, the carbon nanotubes can be recovered to their original structures and recycled. After calculation, we found that B-doped carbon nanotubes not only improved adsorption capacity of O2, but also reduced the activation energy of CO oxidation. According to our research, the higher stability of O2 , the more boron-doped content.
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Chapitres de livres sur le sujet "Metal-free oxidation"

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Cheng, Xin, et Hongguang Guo. « Chapter 6. Metal-free Carbocatalysis for Persulfate Activation Toward Organic Oxidation ». Dans Persulfate-based Oxidation Processes in Environmental Remediation, 145–86. Cambridge : Royal Society of Chemistry, 2022. http://dx.doi.org/10.1039/9781839166334-00145.

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Navalón, Sergio, Raúl Herance, Mercedes Álvaro et Hermenegildo García. « CHAPTER 4. Aerobic Oxidations Using Metal-free Heterogeneous Systems ». Dans Catalysis Series, 78–103. Cambridge : Royal Society of Chemistry, 2020. http://dx.doi.org/10.1039/9781839160332-00078.

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Unglaube, F., et E. Mejía. « CHAPTER 5. Aerobic Oxidations Reactions Using Metal-free Homogeneous Systems ». Dans Catalysis Series, 104–30. Cambridge : Royal Society of Chemistry, 2020. http://dx.doi.org/10.1039/9781839160332-00104.

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Madkour, Loutfy H. « Ecotoxicology of Environmental Heavy Metal Ions and Free Radicals on Macromolecule Cell Organisms ». Dans Nanoparticles Induce Oxidative and Endoplasmic Reticulum Stresses, 1–46. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-37297-2_1.

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Dohi, Toshifumi, et Yasuyuki Kita. « Hypervalent Iodine-Induced Oxidative Couplings (New Metal-Free Coupling Advances and Their Applications in Natural Product Syntheses) ». Dans Hypervalent Iodine Chemistry, 1–23. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/128_2016_667.

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Figadère, B., et X. Franck. « Synthesis by Metal-Free Oxidation ». Dans Three Carbon-Heteroatom Bonds : Acid Halides ; Carboxylic Acids and Acid Salts, 1. Georg Thieme Verlag KG, 2007. http://dx.doi.org/10.1055/sos-sd-020-00158.

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Santana, V. C. S., L. S. Munaretto et E. C. de Lucca, Jr. « 26.1.2.5 Synthesis of Ketones by Oxidation of Alkanes (Update 2022) ». Dans Knowledge Updates 2022/1. Stuttgart : Georg Thieme Verlag KG, 2022. http://dx.doi.org/10.1055/sos-sd-126-00120.

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AbstractThis chapter is an update to Science of Synthesis Section 26.1.2, which included the synthesis of ketones by oxidation of alkanes. This contribution is focused on reports published during the period 2007–2020 that describe the synthesis of ketones by transition-metal catalysis, photochemically and electrochemically mediated methods, as well as the use of supported catalysts and metal-free oxidation of alkanes.
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Yang, Yang, et Qingsheng Gao. « A Mini-Review on High-Efficiency Nanocatalysts for Electrocatalytic Oxidation of Methanol and Ethanol ». Dans Noble-Metal-Free Electrocatalysts for Hydrogen Energy, 529–76. WORLD SCIENTIFIC (EUROPE), 2022. http://dx.doi.org/10.1142/9781800611573_0013.

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Apea-Bah, Franklin Brian, et Trust Beta. « Advances in understanding the nutritional value of antioxidants in wheat ». Dans Improving the nutritional and nutraceutical properties of wheat and other cereals, 29–72. Burleigh Dodds Science Publishing, 2021. http://dx.doi.org/10.19103/as.2021.0087.04.

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Whole grain wheat has a diverse supply of hydrophilic and lipophilic antioxidants which include phenolic compounds (phenolic acids, flavonoids, anthocyanins which are present only in pigmented wheat, alkylresorcinols, and to a lesser extent proanthocyanidins), carotenoids (mainly lutein and zeaxanthin) and tocochromanols (α, β, γ and δ - tocopherols and tocotrienols). This diversity of antioxidants function to protect consumers from radical-induced oxidative damage caused by various free radicals produced endogenously from metabolic processes and exogenously from sunlight and other chemicals and environmental pollutants. They also chelate metal ions which could catalyze oxidation reactions in the physiological system, thereby providing antioxidant protection. However, phenolic compounds might exert pro-oxidant effect when bound to heavy metal ions. This effect could be prevented by the diverse antioxidant system in wheat.
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Oriakhi, Christopher O. « Oxidation and Reduction Reactions ». Dans Chemistry in Quantitative Language. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780195367997.003.0026.

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Oxidation-reduction reactions, or redox reactions, occur in many chemical and biochemical systems. The process involves the complete or partial transfer of electrons from one atom to another. Oxidation and reduction processes are complementary. For every oxidation, there is always a corresponding reduction process. This is because for a substance to gain electrons in a chemical reaction, another substance must be losing these electrons. Oxidation is defined as a process by which an atom or ion loses electrons. This can occur in several ways: • Addition of oxygen or other electronegative elements to a substance:. . . 2 Mg(s)+O2(g) → 2 MgO(s) . . .2 Mg(s)+O2(g) → MgCl2 (s). . . • Removal of hydrogen or other electropositive elements from a substance: . . . H2S(g)+Cl2(g) → 2 HCl(g)+S(s) . . .Here, H2S is oxidized. • The direct removal of electrons from a substance: . . . 2 FeCl2 (s)+Cl2(g) → 2 FeCl3 (s) . . . Fe2+ → Fe3+ +e− . . . Reduction is defined as the process by which an atom or ion gains electrons. This can occur in the following ways: • Removal of oxygen or other electronegative elements from a substance: . . . MgO(s)+H2(g) → Mg(s)+H2O(g). . . • Addition of hydrogen or other electropositive elements to a substance: . . . H2(g)+Br2(g) → 2 HBr(g). . . 2 Na(s)+Cl2(g) → 2 NaCl(s). . . Here, chlorine (Cl2) is reduced. • The addition of electrons to a substance: . . . Fe3+ +e− → Fe2+ . . . Oxidation number or oxidation state is a number assigned to the atoms in a substance to describe their relative state of oxidation or reduction. These numbers are used to keep track of electron transfer in chemical reactions. Some general rules are used to determine the oxidation number of an atom in free or combined state. 1. Any atom in an uncombined (or free) element (e.g., N2, Cl2, S8, O2, O3, and P4) has an oxidation number of zero. 2. Hydrogen has an oxidation number of +1 except in metal hydrides (e.g., NaH, MgH2) where it is −1. 3. Oxygen has an oxidation number of −2 in all compounds except in peroxides (e.g., H2O2, Na2O2) where it is –1.
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Actes de conférences sur le sujet "Metal-free oxidation"

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Sun, Hongqi. « Metal-free modification of graphitic carbon nitride for photocatalytic oxidation ». Dans The 7th International Multidisciplinary Conference on Optofluidics 2017. Basel, Switzerland : MDPI, 2017. http://dx.doi.org/10.3390/optofluidics2017-04268.

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Gole, James L. « Preparation, characterization, and oxidation of small metal clusters ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.fn1.

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Using primarily high flux oven-based metal source configurations small alkali (Lix, Nax,Kx), coinage (Cux, Agx), and group IVA (Six,Gex) metal clusters are being generated in supersonic expansions and agglomerating flows. Both the clusters and their oxidation to form the metal cluster oxides, MnO (n > 2), are being characterized using a combination of single and multiphoton laser fluorescent techniques, chemiluminescence, and mass spectrometry. Photodissociation studies on sodium tri- mer using laser-induced one- and two-photon atom fluorescence spectroscopy (LIAF, TPLIAF) are now being extended to lithium trimer generating a bound-free mirror image spectroscopy which strongly complements the information obtained from bound-bound two-photon spectroscopy. Recent results obtained with an intense copper trimer source demonstrate an ability to (1) study fluorescence from strongly dissociative levels and (2) observe substantial temperature-dependent dynamic changes in spectral features associated with the fluxional nature of copper trimer.
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Ootsuka, F., Y. Tamura, Y. Akasaka, S. Inumiya, H. Nakata, M. Ohtsuka, T. Watanabe, M. kitajima, Y. Nara et K. Nakamura. « Full-Metal-Gate Integration of Dual-Metal-Gate HfSiON CMOS Transistors by Using Oxidation-Free Dummy-Mask Process ». Dans 2006 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 2006. http://dx.doi.org/10.7567/ssdm.2006.j-8-5.

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Gole, James L. « Preparation, characterization, and oxidation of small metal clusters ». Dans International Laser Science Conference. Washington, D.C. : Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.fn1.

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Using primarily high flux oven-based metal source configurations small alkali (Li x , Na x , K x ), coinage (Cu x ,Ag x ), and group IVA (Si x ,Ge x ) metal clusters are being generated in supersonic expansions and agglomerating flows. Both the clusters and their oxidation to form the metal cluster oxides, M n O(n > 2), are being characterized using a combination of single and multiphoton laser fluorescent techniques, chemiluminescence, and mass spectrometry. Photodissociation studies on sodium trimer using laser-induced one- and two-photon atom fluorescence spectroscopy are now being extended to lithium trimer generating a bound-free mirror image spectroscopy which strongly complements the information obtained from bound-bound two-photon spectroscopy. Recent results obtained with an intense copper trimer source demonstrate an ability to (1) study fluorescence from strongly dissociative levels and (2) observe substantial temperature-dependent dynamic changes in spectral features associated with the fluxional nature of copper trimer. Using agglomerated cluster flows and taking advantage of previous experience in the study of chemiluminescent processes across a wide pressure range, we are probing the chemiluminescent emission resulting from the oxidation of small copper (Cu x + O3), silver (Ag x + O3), silicon (Si x + NO2, N2O,O3), and germanium (Ge x + O3, N2O) clusters. From these studies we have obtained the first quantal information on the energy levels and optical signatures of several metal cluster oxides and observed the manifestation of a unique dynamics associated with metal cluster oxidation processes.
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Ghafuri, Hossein, Yegane Rostami, Nastaran Ghanbari, Behnaz Abbasi, Zeinab Tajik et Nasim Amiri Ramsheh. « Gum-Supported Melamine : A Recyclable Reagent for Selective and Metal-Free Oxidation of Benzyl Alcohols ». Dans ECSOC-25. Basel Switzerland : MDPI, 2021. http://dx.doi.org/10.3390/ecsoc-25-11718.

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Durand, Erwann, Nastassia Kaugarenia, Nathalie Barouh, Pierre Villeneuve et Romain Kapel. « Antioxidant chelating peptides production from Rapeseed meal proteins proteolysis. » Dans 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/whcd7145.

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The oxidative chemical degradation produced by reactive species (free radicals, oxygen, etc.) is responsible for the deterioration of most of the formulated products. One of the main properties of an antioxidant lies in its capacity to limit the chemical propagation of oxidation by reducing free radicals. Another strategy to prevent oxidation is binding transition metals, since they are ubiquitous and deeply involved in the initiation and propagation of lipids oxidation. Naturally occurring phospholipids, polyphenols, proteins, or peptides that can bind metal ions could be more valued than synthetic molecules, for human wellbeing, but also to align with consumer preferences. Yet, EDTA salts and sodium citrate remain the most common metal chelators in foods. In this study, we went to investigate a strategy to develop naturally produced antioxidants peptides from edible plant biomass, such as rapeseed. Several enzymatic hydrolyses of total rapeseed protein isolate with various proteases have been performed, and the produced peptides were screened for their antioxidant capacity. Peptides generated with Prolyve® allowed for particularly high Fe2+ chelation capacity (EC50 = 247 ± 27 µg). Accordingly, the enzymatic processing step with Prolyve® was modeled and optimized to minimize reaction costs and maximize peptide recovery. Then, lipid oxidation was studied in the presence or in the absence of chelating peptides, in micellar, bulk, and oil-in-water emulsion systems, and compared with EDTA salts and sodium citrate. Results clearly emphasized a very interesting potential from the peptides sample to prevent lipid oxidation by chelation of transition metals in emulsified models.This result is particularly important to develop the potential of applications of rapeseed meal in various food formulations. In addition, this study emphasized an approach aiming at developing food chelator peptides from plant proteins, having multifunctional properties, and through sustainable processing.
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Ajdelsztajn, Leonardo, Feng Tang, Julie M. Schoenung, Josep Picas, Geoge E. Kim et Virgil Provenzano. « Synthesis and Oxidation Behavior of Nanocrystalline MCrAlY Bond Coats ». Dans ITSC2003, sous la direction de Basil R. Marple et Christian Moreau. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.itsc2003p1517.

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Abstract Thermal barrier coating (TBC) systems protect turbine blades against high-temperature corrosion and oxidation. They consist of a metal bond coat (MCrAlY, M = Ni, Co) and a ceramic top layer (ZrO2/Y2O3). In this work the oxidation behavior of conventional and nanostructured HVOF NiCrAlY coatings has been compared. Commercially available NiCrAlY powder was mechanically cryomilled and HVOF sprayed on a nickel alloy foil to form a nanocrystalline coating. Free-standing bodies of conventional and nanostructured HVOF NiCrAlY coatings were oxidized at a 1000°C for different time periods in order to form the thermally grown oxide (TGO) layer. The experiments show an improvement in oxidation resistance in the nanostructured coating when compared to that of the conventional one. This behavior is a result of the formation of a continuous Al2O3 layer on the top surface of the nanostructured HVOF NiCrAlY coating. This layer protects the coating from further oxidation and avoids the formation of mixed oxide protrusions present in the conventional coating.
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Fukumoto, M., T. Nishiyama et E. Nishioka. « Effect of Surface Morphology of Substrate on Flattening Behavior of Freely Fallen Metal Droplet ». Dans ITSC2002, sous la direction de C. C. Berndt et E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2002. http://dx.doi.org/10.31399/asm.cp.itsc2002p0037.

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Abstract Most metallic and ceramic splats exhibit temperature-dependent behavior when they strike a metal substrate and assume a shape that suggests temperature-dependent wetting properties. In this study, the authors investigate the relationship between high-temperature oxidation, substrate morphology, and the flattening behavior of free-falling droplets. Substrate surfaces are examined by means of atomic force microscopy, which shows that changes in morphology of just a few nanometers can have an effect on flattening behavior. Paper includes a German-language abstract.
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Ordonez, Richard C., Noah Acosta, Jordan Melcher, Nackieb Kamin et David Garmire. « Investigation of Liquid Metal Ohmic Contacts for Graphene Photonic Devices ». Dans ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48567.

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We demonstrate the first contact resistance measurements of graphene–galinstan (g-g) ohmic contacts in an effort to improve the performance of graphene photonic devices. The nobility of carbon materials provide an interesting graphene sensor application to explore an oxidation free liquid metal - semimetal interface that can be used to lower contact resistance at source/drain terminals of a standard graphene phototransistor. Our methods utilize photopolymerization of the reactive monomer Trimethlylolpropane Triacrylate (TMPTA) in order to fabricate micro structures necessary to overlay liquid metal contacts on graphene. With the use of an industry standard transfer length method (TLM), a contact resistance of −124±28Ω was measured at both standard temperature and pressure. The results from our study suggest that liquid metals such as galinstan are comparable alternatives to rigid semiconductor interfaces and demonstrates interesting boundary characteristics that may lead to heavy chemical doping and associated low resistance contacts that are required to increase sensitivity in graphene photonic devices.
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Liu, Yacheng, Weidong Fan, Xiang Zhang et Naixing Wu. « Analysis on High Temperature Corrosion Behaviors of Boiler Steels Under High-Chlorine Coal Ash ». Dans ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3215.

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Chlorine is a harmful constituent in coal, contributing to severe high temperature corrosion on the super-heater and re-heater tubes in utility boiler firing high-chlorine coal (more than 0.3 wt.%). Characteristics of the corrosion contain not only the formed products on the metal surface, but also intergranular attack inner the alloy, resulting in great potential safety hazard and economic loss. The prevailing Cl-related mechanisms of high temperature corrosion involve active oxidation and fluxing, which mean both corrosive elements in the flue gas and deposits on the boiler metal surface can accelerate the corrosion. Cl2 as a catalyst in active oxidation can be released by sulfuration of alkali metal chlorides or reactivity by alkali metal chlorides with chromium/chromium oxide and iron/iron oxide or oxidation of HCl. However, the formation of low-melting eutectics (such as NaCl-Na2CrO4) in mechanism of fluxing can be an induction of severe corrosion because the rate of molten corrosion is much higher than chemical corrosion. Lab-scale experiments simulating the flue gas species, temperature gradient from hot flue gas (950 °C) to cold metal (610 °C), and deposit (four various Cl-containing coal ash) on the specimens were conducted in a tube furnace to investigate the corrosion of three common boiler steels (12Cr1MoVG, T91, TP347H). Furthermore, with the aid of the scanning electronic microscope associated with energy dispersive spectrometer (SEM-EDX) and X-ray diffraction instrument (XRD), the appearance and microstructure, the element contents, and composition of corrosion products on the specimens after corrosion have been analyzed. For high-chlorine coal, there existed white crystal on the surface of specimens (T91, TP347H) after corrosion test, and the XRD result showed NaCl, which can be explained by evaporation-condensation mechanism. However, no white crystal was detected for 12Cr1MoVG and it can be inferred that thick corrosion product layer with high thermal resistance was formed and 12Cr1MoVG suffered severe degradation. Through comparisons of alloy elements corroded in various oxidizers (Cl2, O2, and S), it can be seen that as the metal temperature increases, the negative value of Gibbs free energy for alloy elements corroded in Cl2 becomes higher, but the value is less corroded in O2 or S. Thus, alloy elements tend to be easier combined with Cl2, and Cl-induced corrosion is aggravated with the temperature increases. Similar results can be obtained by increased equilibrium vapor pressures of metal chlorides, evaporating easily and diffusing towards further to be oxidation. In comparison with high-chlorine coal, the corrosivity of low-chlorine coals on specimens were weak, especially for TP347H characterized with higher contents of Cr and Ni. Furthermore, the higher the ratio of Cl/2S or Cl/Na in the coal ash is, the more severe corrosion the specimens suffer.
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Rapports d'organisations sur le sujet "Metal-free oxidation"

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Kanner, Joseph, Dennis Miller, Ido Bartov, John Kinsella et Stella Harel. The Effect of Dietary Iron Level on Lipid Peroxidation of Muscle Food. United States Department of Agriculture, janvier 1995. http://dx.doi.org/10.32747/1995.7604282.bard.

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Biological oxidations are almost exclusively metal ion-promoted reactions and in ths respect iron, being the most abundant, is the commonly involved. The effect of dietary iron levels on pork, turkey and chick muscle lipid peroxidation and various other related compounds were evaluated. Crossbred feeder pigs were fed to market weight on corn-soy rations containing either 62, 131 or 209 ppm iron. After slaughter, the muscles were dissected, cooked and stored at 4°C. Heavily fortifying swine rations with iron (>200 ppm) increase nn-heme iron (NHI), thiobarbituric acid reactive substances (TBARS), and decrease a-tocopherol in cooked stored pork but did not increase warmed-over aroma (WOA). NHI and TBARS were higher in cooked pork from pigs fed high-iron diets. Liver iron correlated with muscle iron. TBARS were strongly related with WOA. The role of dietary vitamin E and ascorbic acid on Fe-induced in vivo lipid peroxidation in swine was also evaluated. Moderate elevation in iron stores had a marked effect on oxidative stress, especially as indicated by liver TBARS. Supplemental vitamin E, and to a lesser extent vitamin C, protect against this oxidative stress. Unsupplementation of Fe in the regular diet of turkeys did not affect body weight, blood hemoglobin level, or iron pool in the liver or muscle. The reason being that it contained "natural" ~120 mg Fe/kg feed, and this amount is high enough to keep constant the pool of iron in the body, liver or muscle tissues. Only Fe-supplementation with high amounts of Fe (500 ppm) significantly increased turkey blood hemoglobin and total iron in the liver, in 1 out of 3 experiments, but only slightly affects iron pool in the muscles. It seems that the liver accumulates very high concentations of iron and significantly regulates iron concentration in skeletal muscles. For this reason, it was very difficult to decrease muscle stability in turkeys through a diet containing high levels of Fe-supplementation. It was shown that the significant increase in the amount of iron (total and "free") in the muscle by injections with Fe-dextran accelerated its lipid peroxidation rate and decreased its a-tocopherol concentration. The level and metabolism of iron in the muscles affects the intensity of in vivo lipid peroxidation. This process was found to ifluence the turnover and accumulation of a-tocopherol in turkey and chick muscles. Treatments which could significantly decrease the amount and metabolism of iron pool in muscle tissues (or other organs) may affect the rate of lipid peroxidation and the turnover of a-tocopherol. Several defense enzymes were determined and found in the turkey muscle, such as superoxide dismutase, catalase, and glutathione peroxidase. Glutathione peroxidase was more active in muscles with a high trend of lipid peroxidation, lmore so in drumsticks than in breast muscles, or muscles with a low a-tocopherol content. The activity of glutathione peroxidase increased several fold in muscle stored at 4°C. Our work demonstrated that it will be much more practical to increase the stability of muscle tissues in swine, turkeys and chickens during storage and processing by increasing the amount of vitamin E in the diet than by withdrawing iron supplementation.
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