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BAI, XISHAN. "(CYCLOPENTADIENONE)IRON COMPLEXES IN REACTIONS INVOLVING HYDROGEN TRANSFER." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/695447.
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The PhD project focused on the synthesis and catalytic applications of (cyclopentadienone)iron complexes in reactions involving hydrogen transfer. The manuscript is divided into five chapters, and after a rather comprehensive review on the state of the art in chapter 1, the thesis describes, in the remaining four chapters, the original achievements of the PhD candidate. In particular, chapter 2 describes the applications of highly active [bis(hexamethylene)cyclopentadienone]iron tricarbonyl pre-catalyst for the reduction of imine bonds under transfer hydrogenation conditions and for the reductive amination of carbonyl compounds. In chapter 3, the application of the above mentioned pre-catalyst to alcohol amination reactions via a hydrogen borrowing mechanism is discussed. Chapter 4 deals with enantioselective ketone hydrogenations using chiral (cyclopentadienone)iron complexes containing a stereogenic plane (prepared in racemic form and resolved by chiral HPLC), and with the synthesis of chiral macrocyclic (cyclopentadienone)iron complexes, putatively more suited for the transfer of the chiral information from the catalyst to the substrate. Finally, Chapter 5 describes the immobilization of (cyclopentadienone)iron complexes into a solid support, namely Metal Organic Frameworks (MOFs), to realize an active heterogeneous (cyclopentadienone)iron catalyst for catalyst recycling in batch hydrogenation reactions and potential applications in flow processes.
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Cettolin, M. "IRON AND RUTHENIUM CATALYSTS FOR THE REDUCTION OF C=O AND C=N BONDS." Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/543550.
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In this PhD thesis recent developments in Iron and Ruthenium Catalysts for the Reduction of C=O and C=N bonds are reported. In Part A the synthesis and reactivity of new iron complexes promoting the reduction of C=O and C=N bonds is reported. The state of the art in homogenous iron catalyzed hydrogenations is introduced in Chapter 1 followed by the results obtained with each class of iron complexes. Chapter 2 shows the synthesis, characterization and reactivity of BINOL-derived tetra isonitrile iron complexes. Two different families were designed differing in the length of the arm bearing the isonitrile group. Those complexes proved to promote asymmetric transfer hydrogenation (ATH) and asymmetric hydrogenation (AH) of acetophenone under basic conditions. Although the initial results were encouraging, the further attempts to improve the performances were mostly ineffective. Lack of activity, enantioselectivity and reproducibility issues convinced us to not proceed further.
Chapter 3 reports a new class of isonitrile-phosphine ligands called PCCP: a chelating system bearing phosphine and isonitrile groups in the same BINOL-derived scaffold. Design, synthesis and characterization of the PCCP ligand are here reported. Once the corresponding iron complex was obtained, ATH of acetophenone was performed but only racemic 1-phenylethanol was yielded. Synthesis of the second generation of PCCP is still undergoing.
Chapter 4 is mainly dedicated to the synthesis and the catalytic properties of the (cyclopentadienone)iron pre-catalyst [bis(hexamethylene) cyclopentadienone] iron complex 81. In the first part of the chapter the synthesis of 81 by the reaction of cyclooctyne with Fe(CO)5 and the investigation of its catalytic properties in C=O bond reduction is reported. As a result of the peculiar reactivity of cyclooctyne, 81 was formed in good yield (56%) by intermolecular cyclative carbonylation/complexation with Fe(CO)5. 81 was fully characterized and its crystal structure was determined by using XRD. Catalytic tests revealed that, upon in situ activation with Me3NO, 81 promotes the hydrogenation of ketones, aldehydes, and activated esters as well as the transfer hydrogenation of ketones and shows a higher activity than the classical “Knölker complex” 30. Studies on the hydrogenation kinetics in the presence of 81 and 30 suggest that this difference in activity is probably caused by the better stability of the 81-derived complex than that of the in situ generated Knölker–Casey catalyst. In the second part of Chapter 4 the first catalytic transfer hydrogenation of non-activated imines promoted by a Fe-catalyst 81 in the absence of Lewis acid co-catalysts is reported. Use of the (cyclopentadienone)iron complex 81 allowed to reduce a number of N-aryl and N-alkyl imines in very good yields using iPrOH as hydrogen source. The reaction proceeds with relatively low catalyst loading (0.5-2 mol%) and, remarkably, its scope includes also ketimines, whose reduction with a Fe-complex as the only catalyst has little precedents. Based on this new methodology, we developed a one-pot catalytic transfer hydrogenation protocol for the reductive amination of aldehydes/ketones, which provides access to secondary amines in high yield without the need to isolate imine intermediates.
Chapter 5 is focused on the catalytic performances of BINOL-derived (cyclopentadienone)iron complexes recently synthesized in our group. Those iron complexes showed good activity in asymmetric hydrogenation of ketones and although the ee values are clearly inferior to the best literature examples of ketone asymmetric hydrogenation, they still represent the best results obtained so far with chiral (cyclopentadienone)iron complexes. Their reactivity in imine reduction (AH and ATH) was investigated and the results are reported. Both pre- and in situ formed imines were screened and promising results were obtained for acetophenone-derived imines.
Part B of this thesis is focused on the use of ruthenium and Trost Ligand as catalyst for asymmetric hydrogenation of ketones. This research was carried out during my Erasmus+ Placement in LIKAT (Leibniz Institute for Catalysis, Rostock, Germany) under the supervision of Prof. Dr. J.G. de Vries and Dr. Sandra Hinze.
In Chapter 6, we described the use of Trost ligand as ligand in the AH of ketones. Trost ligand was screened in the presence of several metal salts and found to form active catalysts when combined with ruthenium sources in the presence of hydrogen and a base. Reaction optimization was carried out by screening different Ru sources, solvents and bases. Under the optimized conditions, the complex formed by combination of Trost ligand with RuCl3(H2O)x in the presence of Na2CO3, is able to promote the AH of several ketones at r.t. with good yields and up to 96% ee. The reaction kinetics measured under the optimized conditions revealed the presence of a long induction period, during which the initially formed Ru species is transformed into the catalytically active complex by reaction with hydrogen.
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SARKAR, ABHIJNAN. "HETEROGENEOUS IRON CATALYZED CYCLOPROPANATION REACTION." Doctoral thesis, Università degli Studi di Milano, 2020. http://hdl.handle.net/2434/698432.
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Until now, NGR (nitrogen-enriched graphene) catalysts have mostly been employed for hydrogenation/oxidation reactions. In this piece of work, we expand the field of applicability of an iron NGR catalyst to cyclopropanation reactions. In this work, a heterogeneous Fe-based nitrogen-doped carbon supported catalyst has been successfully employed for the cyclopropanation reaction of alkenes. According to best of our knowledge, this is the first example of a heterogeneous Fe-catalyzed cyclopropanation reaction in today's date. These kinds of materials, generally employed for reduction or oxidation reaction, are now indeed effective catalyst also for carbene transfer reactions. The activity of Fe/Phen@C-800in the reaction was initially explored by using ethyl diazoacetate and α-methylstyrene as substrates as the model transformation. Various parameters such as solvent, temperature, time and catalyst support etc. were changed. The nature of the solvent has a minimal influence both on the reaction yield and diasteroselectivity making this reaction versatile from the media profile. The variation of the reaction temperature furnished the product in slightly lower yield. When a 5-fold amount of the olefin with respect to the diazo compound was used, homocoupling products (diethyl fumarate and diethyl maleate) deriving from EDA were detected in very low amount (<5 %). Even when the amount of olefin was decreased (1.5 eq) homocoupling side products increased, although a very good yield of the cyclopropane was maintained, demonstrating the applicability of the procedure even to more expensive olefins. Interestingly, the catalyst is water tolerant and only a slight decreased yield was obtained using a “wet” solvent. A change in the catalyst support from carbon to inorganic oxides (MgO or SiO2) does not significantly affect the yield and the diastero selectivity. Furthermore control experiments effected by employing catalysts prepared by the same procedure employed for Fe/Phen@C-800, but omitting either Fe(OAc)2 or Phen, resulted in no detectable formation of cyclopropane. Fe/Phen@C-800-catalysts showed good results in dimethoxyethane at 60 °C for 4 h, affording high yields of the desired cyclopropanes (mixture of cis and trans isomers) and only <5 % ethyl maleate and fumarate. The model reaction has been successfully scaled-up to 15-fold without significant variations of yield and diasteroisomeric ratio. The developed protocol allows obtaining several cyclopropanes from aromatic and aliphatic olefins and different diazocompounds. High to excellent yields were obtained for terminal olefins, including geminally substituted ones. Aliphatic olefins require longer reaction times. A moderate trans diastereoselectivity was observed in all cases. The catalysts do not show any activity towards internal olefins and can be used to selectively cyclopropanate a terminal olefin in a substrate containing both internal and terminal olefinic groups. The selectivity for the terminal double bond can be explained by the lack of activity of the catalyst in the case of internal olefins, most likely due to a hindered approach of the substrate to the carbene formed on the surface of the catalyst. Mono substituted diazo compounds (ester or ketone) afforded the corresponding cyclopropanes in excellent yields. More sterically demanding diazocompounds such as t-BDA has a dramatic effect on the diasteroselection, furnishing the cis- isomer only in traces. Disubstituted diazomethanes proved to be more challenging. Mono substituted diazo compounds such as diphenyldiazomethane failed to afford corresponding cyclopropanes under standard conditions, although it yielded the product in moderate yield at a higher temperature and longer reaction time (100 °C for 8h in toluene), while the more stable diazomalonate did not react even under these conditions. The catalysts was recycled several times, but a gradual deactivation is immediately observed since the first recycle. In principle, the loss of activity can be attributed either to metal leaching or to deactivation of the catalyst. After the first recycle, ICP analysis of the solution showed that only 0.1% of the initial iron had been lost in solution. This result indicates that the loss of recycling ability is not due to metal leaching. In order to make the whole process both efficient and effective, two routes of reactivation were explored. Attempted reactivation of the catalyst at 300 °C seems to have a slightly positive effect but that at 400 °C is not effective. The initial catalyst activity was effectively restored using an oxidative reactivation protocol under mild conditions (H2O2, 3 v/v% aqueous solution), which may be of more general use even for other reactions if olefins or other polymerizable compounds are employed as substrates. Oxidative regeneration is typical for catalyst that suffer of physicochemical deactivation (e.g. fouling or poisoning). Indeed, we verified that complete deactivation of the catalyst occurs even by treating the material only with styrene under the reaction conditions and the activity is restored by oxidative treatment. This result indicates the polymerization of the olefin on the catalytic surface as a possible cause for the deactivation rather than a mechanical or thermal modification of the catalyst.
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BRENNA, DAVIDE. "SUSTAINABLE PREPARATION OF APIS IN BATCH&FLOW MODE, AND IRON CATALYZED TRANSFORMATIONS." Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/585122.
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During my PhD, we focused our attention on the application of the green chemistry principles for the preparation of active pharmaceutical ingredients (API) and, more in general, of highly functionalized chiral molecules, as fine chemicals or building blocks of high value for further synthetic manipulations. Mainly the topics of our interest will be divided in three main chapters:
1- The use of a cheap and green reducing agent, HSiCl3, for imines reduction either in batch and flow mode.
2- The use of 3D-printed reactors for the preparation of APIs, engineering new reactors in order to perform continuous multi-step synthesis.
3- a) The use of iron complexes, the Knolker type, for the hydrogenations of chiral imines.
b) The use of cheap and readily available Iron complex, Fe(hmds)2, for the trimerization of acetylenes, using for the first time a reducing agent free protocol.
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Paliga, James Francis. "Developing Earth-abundant metal-catalysts for hydrofunctionalisation." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31115.
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The iron-catalysed hydromagnesiation of styrene derivatives has been developed further from previous publications, expanding the electrophile scope to enable the regioselective formation of new carbon-carbon and carbon-heteroatom bonds (Scheme A1). A commercially available pre-catalyst and ligand were used to give an operationally simple procedure that did not require prior synthesis of a catalyst. This work also investigated the hydromagnesiation of dienes, using a screen of ligands commonly used in transition metal catalysis. An investigation into the magnesium-catalysed hydroboration of olefins was also carried out. Although mostly unsuccessful, it was demonstrated that in the presence of a magnesium catalyst, a small amount of vinyl boronic ester could be formed from an alkyne (Scheme A2). Simple magnesium salts were also investigated for the reduction of carbonyls. Lastly, this work explored the titanium-catalysed hydrosilylation of olefins, using a novel activation method developed within the group (Scheme A3). The results were compared to those published previously using traditional organometallic activation methods and attempts at identifying conditions to improve chemoselectivity were carried out.
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Chalivendra, Saikumar. "Catalytic Destruction of Lindane Using a Nano Iron Oxide Catalyst." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1324497492.
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Min, Zhenhua. "Catalytic steam reforming of biomass tar using iron catalysts." Thesis, Curtin University, 2010. http://hdl.handle.net/20.500.11937/184.
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Biomass has become an increasingly important renewable source of energy forenhanced energy security and reduced CO[subscript]2 emissions. Gasification is at the core of many biomass utilisation technologies for such purposes as the generation of electricity and the production of hydrogen, liquid fuels and chemicals. However, gasification faces a number of technical challenges to become a commercially feasible renewable energy technology. The most important one is the presence of tar in the gasification product gas. The ultimate purpose of this thesis was to investigate the catalytic reforming of tar using cheap catalysts as an effective means of tar destruction.In this thesis, natural ilmenite ore and novel char-supported catalysts were studied as catalysts for the steam reforming of biomass tar derived from the pyrolysis of mallee biomass in situ in two-stage fluidised-bed/fixed-bed quartz reactors. In addition to the quantification of tar conversion, the residual tar samples were also characterised with UV-fluorescence spectroscopy. Both fresh and spent catalysts were characterised with X-ray diffraction spectroscopy, FT-Raman spectroscopy and thermogravimetric analysis.The results indicate that ilmenite has activity for the reforming of tar due to its highly dispersed iron-containing species. Both the externally added steam and low concentration oxygen affect the tar reforming on ilmenite significantly. The properties of biomass affect the chemical composition of its volatiles and therefore their reforming with the ilmenite catalyst. Compared with sintering, coke deposited on ilmenite is the predominant factor for its deactivation.During the steam reforming process, the char-supported iron/nickel catalysts exhibit very high activity for the reforming of tar. In addition, NO[subscript]x precursors could be decomposed effectively on the char-supported iron catalyst during the steam reforming process. The hydrolysis of HCN and the decomposition of NH[subscript]3 on the catalyst are the key reactions for the catalytic destruction of NO[subscript]x precursors.The kinetic compensation effects demonstrate that the reaction pathways on the char-supported catalysts are similar but different from those on ilmenite. The proprieties of catalyst support could play important roles for the activities of the catalysts and the reaction pathways on the catalysts. The char support as part of the char-supported catalysts can undergo significant structural changes during the catalytic reforming of biomass volatiles.
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Neate, Peter Gregory Nigel. "Pathways to sustainable catalysis : from novel catalysts to mechanistic understanding." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/25441.
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Catalysis allows for the controlled formation of new bonds, whilst reducing both time and energy expenditure in the process. Catalysis has traditionally been the realm of precious metals, which have been used to carry out a bewildering array of reactions. However, there is an ever-increasing drive for the development of catalytic methodology employing sustainable and environmentally benign catalysts. Two such candidates are organocatalysis, omitting the need for metals where possible, or the use of iron catalysis. Two key areas to the advancement of the of field catalysis are the identification and development of new catalysts as well as an understanding of the mechanisms of established catalytic processes. Novel catalysts can provide many benefits such as enhanced or even novel reactivity, access to new classes of substrates or simply be more readily accessible compared with previously developed catalysts. To this end, the first example of Lewis-base-catalysis using the recently developed cyclopropenimine motif is reported. This was exploited in the trifluoromethylation of aldehydes and ketones using the Rupert-Prakash reagent (Scheme A-1). Scheme A-1 Cyclopropenimine-catalysed trifluoromethylation of aldehydes and ketones Developing an understanding of catalytic methodologies in the terms of their mechanism and active species is also a key area in catalysis. Insight into these can direct the expansion of these systems in terms of both more effective catalysts and tailoring reaction conditions as examples. The iron-catalysed hydromagnesiation of styrene derivatives was studied in detail. This culminated in a proposed mechanism, involving a novel hydride transfer process (Scheme A-2). Studies were carried out using a combination of kinetic analysis and in situ Mössbauer spectroscopy, as well as successfully isolating and studying the reactivity of a catalytically-relevant, formal iron(0)-species.
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Madadkhani, Shiva. "Red mud as an iron-based catalyst for catalytic cracking of naphthalene." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/60118.
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Reducing the tar content in the producer gas of biomass gasification processes remains one of the main challenges in the commercialization of this technology and, hence, the development of clean and economical tar-removing technologies is becoming increasingly important. Catalytic tar removal has the advantage of avoiding expensive gas cleaning systems while maintaining the sensible heat in the producer gas. Commercial catalysts based on noble metals and metal oxides have shown good activity towards tar destruction, but are prone to rapid deactivation. This in addition to the high replacement cost provide the rationale for the development of low-cost alternatives. Red mud, a by-product from bauxite processing, has received considerable attention in this regard due to its high iron content in the form of ferric oxide (Fe₂O₃), high surface area, and its resistance to sintering and poisoning. However, very few studies have been conducted to investigate red mud as a potential catalyst for catalytic tar removal. The aim of this study was to develop a catalyst from red mud for the removal of naphthalene, as a model compound for gasification tar. Red mud catalyst pellets were produced from raw red mud slurry, and their properties were investigated by measuring the chemical composition, surface area, and pore size distribution. Subsequently, the ability for tar decomposition was studied by passing naphthalene-nitrogen and naphthalene-hydrogen mixtures through a bed of the catalyst at five space velocities in the range of 4500-19,000 h-¹, and at reactor temperatures of 500, 600, 700 and 800°C. Catalytic cracking tests confirmed that red mud possesses a very high intrinsic catalytic activity for naphthalene conversion even at temperatures as low as 500°C and space velocities as high as 19,000 h-¹. Kinetic analysis was also performed to determine the apparent reaction order, the kinetic rate constants as well as the activation energy of the reaction. Long term tests of the catalyst showed that the activity of the catalyst diminished over time when no hydrogen was present in the system; however, in the presence of H₂ the activity was found to remain > 90% for 14 h.Applied Science, Faculty of
Graduate
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Wei, Duo. "Iron, manganese and rhenium-catalyzed (de)hydrogenation and hydroelementation reactions." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S105.
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L’objectif de ce travail doctoral a été de développer de nouvelles méthodes éco-compatibles pour réaliser efficacement des réactions de (dé)hydrogénation et d’hydroélémentation catalysées par des catalyseurs bien définis de fer, de manganèse et également de rhénium. La première partie de ce travail porte sur le développement des premiers exemples de réaction de borylation de dérivés styrènes et acétyléniques terminaux avec le pinacolborane via une réaction d’activation de liaison C-H catalysée par des systèmes à base de Fe(PMe3)4 ou de Fe(OTf)2/ DABCO. Dans une seconde partie, des complexes de fer à base de ligands carbènes N-hétérocycliques (NHC) tels que Fe(CO)4(IMes) et [CpFe(CO)2(IMes)][I] ont été efficacement utilisés pour la synthèse d’une grande variété d’amines cycliques (pyrrolidines, pipéridines et azépanes) via une réaction d’amination réductrice catalytique en présence d’hydrosilanes. De façon très intéressante, les catalyseurs commerciaux Mn2(CO)10 et Re2(CO)10 en présence de triéthylsilane, ont permis de réduire sélectivement les esters, acides carboxyliques et amides en acétals, alcools et amines correspondants. En complément de l’hydrosilylation, l’hydrogénation d’aldéhydes, cétones et aldimines a pu être efficacement menée grâce à l’utilisation de nouveaux précatalyseurs bien définis de manganèse à base de ligands bidentes facilement accessibles tels que la pyridinyl-phosphine et la 2-picolylamine. Dans la continuité de notre intérêt pour le développement de nouveaux catalyseurs à base de métaux du groupe 7, une série de complexes de rhénium coordinés à des ligands amino-bisphosphino a montré une excellente aptitude à promouvoir l’hydrogénation de composés carbonylés (aldéhydes, cétones), la mono-méthylation sélective d’amines avec le méthanol comme agent de méthylant durable et la synthèse quinolines substituées. La dernière partie de se travail décrit le développement d’oxydations aérobies d’amines pour préparer des aldimines, des composés N-hétéroaromatiques et des dérivés de type benzoimidazole via une catalyse au manganèse en l’absence de ligands ou d’additifsThis research work is aimed at developing advanced eco-friendly methodologies in the area of iron, manganese and rhenium-catalyzed (de)hydrogenation and hydroelementation reactions. Initially, we reported the first examples of highly selective catalytic direct C-H borylation of styrene derivatives and terminal alkynes with pinacolborane using Fe(PMe3)4 and Fe(OTf)2/DABCO as catalyst systems, respectively. Afterwards, N-heterocyclic carbene (NHC) based iron complexes Fe(CO)4(IMes) and [CpFe(CO)2(IMes)][I] were efficiently employed in the catalytic reductive amination reactions with hydrosilanes to access a large variety of cyclic amines (pyrrolidines, piperidines and azepanes). Interestingly, with the commercially available Mn2(CO)10 or Re2(CO)10 as catalyst and Et3SiH as an inexpensive hydrosilane source, carboxylic esters, acids and amides can be chemospecifically reduced to the corresponding acetals, alcohols and amines. Besides hydrosilylation, we also explored the application of a series of well-defined manganese pre-catalysts featuring readily available bidendate pyridinyl-phosphine and 2-picolylamine ligands in hydrogenation reactions of aldehydes, ketones and aldimines. In line with our interest in developing group 7 metals based catalysts, we have also demonstrated that a series of amino-bisphosphino ligands coordinated rhenium catalysts can efficiently promote the hydrogenation of carbonyl derivatives, the mono N-methylation of anilines with methanol and the dehydrogenative synthesis of substituted quinolines. Lastly we also developed the Mn-catalysed ligand- and additive-free aerobic oxidation of amines to prepare aldimines, N-heteroaromatics and benzoimidazole derivatives
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Jones, Alison Sarah. "From palladium to iron : towards more sustainable catalysis." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10461.
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The construction of bonds in a controlled and selective manner and the development of operationally simple, general and reliable methods to achieve these aims remains a key goal of chemical synthesis and the countless industries it impacts upon. With this in mind, the chemo-, regio- and stereoselective introduction of a number of functionalities into small molecules was investigated. Traditionally the majority of functionalisations have used precious metals; the scope of transformations that can be achieved using these catalysts is remarkable. Palladium in particular has found widespread application in new bond-forming processes and, in addition to cross-coupling reactions, palladium catalysis has been used to effect a wide variety of asymmetric reactions. This work describes investigations into the palladium-catalysed enantioselective electrophilic fluorination of azaarylacetates and amides A2 and the oxidative annulation of ferrocene derivatives A4 (Scheme A1). Both products have structural significance; heterocycles and stereogenic fluorinated centres, present in A3, are important motifs in the pharmaceutical industry, and ferrocenes are important rigid scaffolds in chiral ligands such as those in the Josiphos family e.g. A7. Scheme A1. Palladium catalysis for a) enantioselective fluorination and b) oxidative annulation Whilst a general catalyst remained elusive for the asymmetric fluorination of azaarylacetates and amides, benzoxazole-containing substrates were consistently fluorinated with excellent enantioselectivity (up to 96% ee) using palladium catalyst A1 (Scheme 1a). The oxidative annulation of ferrocene derivatives proved challenging and although the reaction was successful, the product could only be isolated in up to 24% yield (Scheme 1b). In order to determine the yield-limiting step of the reaction, mechanistic studies were conducted and palladacycle A6 was synthesised as a possible reaction intermediate. Recently there has been a shift towards the development of more sustainable, environmentally benign and economic catalyst systems and iron is quickly becoming recognised as a viable alternative owing to its high natural abundance and low toxicity. A general iron-catalysed hydrofunctionalisation procedure is described that was used to form a wide variety of carbon-carbon and carbon-heteroatom bonds (Scheme A2). Scheme A2. Iron catalysis for carbon-carbon and carbon-heteroatom bond formation With just 0.5 mol% iron catalyst, the broad scope formal hydrofunctionalisation of styrene derivatives was achieved using commercially available and bench-stable catalysts and reagents. An iron-catalysed highly regioselective hydromagnesiation gave a common benzylic Grignard reagent, which was reacted with an array of electrophiles in a highly chemo- and regioselective manner. Significantly, the products of formal hydroboration, hydrosilylation and cross-coupling reactions were obtained.
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Ayub, Ibrar. "Oxidation and reduction properties of iron-containing oxides." Thesis, n.p, 2001. http://ethos.bl.uk/.
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Ali, H. Saad Moh'd. "Selective catalytic oxidation of ammonia using copper and iron supported on ZSM-5 catalysts." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525661.
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Asiri, Nawras A. "Selective Catalytic Oxidation of Organic Sulfides by Iron (III) Porphryin Catalysts and Generation of Iron (IV)-OXO Prophyrin Radical Cations." TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1290.
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Macrocyclic ligand-complexed transition metal-oxo intermediates are the active oxidizing species in a variety of important biological and catalytic oxidation reactions. Many transition metal catalysts have been designed to mimic the predominant oxidation catalysts in nature, namely the cytochrome P450 enzymes. Iron porphyrin complexes have been the center of research as catalysts. In this study 5,10,15,20- tetramesitylporphyrin (H2TMP) and its corresponding iron complexes FeIII(X)TMP (X= Cl, ClO4, ClO3, NO3, NO2, and BrO3) have been successfully synthesized and fully characterized by UV-vis and NMR spectroscopies. For the catalytic selective oxidation of organic sulfides, the potential of iron(III) porphyrin complexes with iodobenzene diacetate [PhI(OAc)2] have been investigated. Iodobenzene diacetate was found to be an efficient oxygen source in the iron(III) porphyrin-catalyzed oxidation of sulfides to sulfoxides. Iron(III) porphyrin catalysts show an excellent conversion and selectivity for the sulfoxidation reactions. Reaction conditions and environments that effect the catalytic sulfoxidation including solvent, catalytic amount, axial ligand, water, and thioanisole substrates, have been investigated to identify the optimal conditions and the substrate scope. Under optimized conditions, excellent substrate conversions (up to 100%) as well as product selectivies (sulfoxide:sulfone > 95:5) have been achieved. To probe the nature of the oxidizing species in above catalytic sulfoxidations, iron(IV)-oxo porphyrin radical cations model of Compound I were chemically produced from the corresponding iron(III) tetramesitylporphyrin precursors with excess amounts of PhI(OAc)2 (20-50 equivalents) in CH3CN solvent. All O=FeIV(X)TMP·+ (X= Cl, ClO4, ClO3, and NO3) show weaker Soret band and broader Q band that are characteristic of Compound I analogues. A new photochemical method that led to generation of the iron(IV)-oxo porphyrin radical cations was also successfully developed. Iron(IV)-oxo porphyrin radical cations were generated by irradiation of iron(III) porphyrin chlorate or bromate complexes that result in heterolytic cleavage of the O-X bond in the axial ligand.
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Toummini, Dounia. "Arylation de nucléophiles, par catalyse au cuivre ou au fer, ou en milieu superbasique en absence de métal de transition." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2014. http://www.theses.fr/2014ENCM0001.
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Cette thèse s'inscrit dans le cadre très général de la recherche de nouvelles méthodes de synthèse éco-compatibles. Dans la première partie, intitulée « Arylation catalysée au cuivre d'hétérocycles azotés par des sels d'aryldiazonium», nous avons présenté nos travaux décrivant le premier exemple d'une réaction de type Sandmeyer permettant la formation d'une liaison carbone-azote (C-N). Nos systèmes permettent, en effet, l'arylation de nucléophiles azotés, essentiellement de type pyrazole, à partir d'électrophiles d'aryldiazoniums. Les motifs obtenus, les arylpyrazoles, sont des molécules extrêmement répandues, aux nombreuses applications dans le domaine des sciences de la vie mais aussi des matériaux.Les conditions que nous utilisons sont extrêmement douces puisqu'elles ne font appel qu'à des quantités catalytiques de cuivre et d'acide acétique. Par ailleurs, ce système fonctionne à température ambiante sans nécessiter la présence de ligands, additifs ou bases.Enfin l'azote (N2) libéré dans le milieu est inerte et sans impact dans le milieu réactionnel.Dans une seconde partie, intitulée « Synthèse des biaryles symétriques à partir des aryllithiens, en présence d'un catalyseur au fer », nous avons décrit un nouveau système catalytique au fer, permettant la synthèse directe de dérivés biaryliques symétriques à partir d'arylithiens générés in situ et d'halogénures d'aryles, dans des conditions de températures très douces en utilisant un système catalytique au fer, en absence de ligands. La procédure, qui se déroule via l'échange quantitatif in situ d'halogénure d'aryle avec les alkyllithiums, permet un excellent contrôle de la réactivité et de la sélectivité.Enfin, dans une dernière partie intitulée « Synthèse directe des biarylméthanes sans un métal de transition », nous avons mis en évidence une nouvelle méthode de synthèse de biarylméthanes dissymétriques par couplage en milieu super basique de cétones benzyliques énolisables avec des dérivés aromatiques iodés. Dans ces conditions, la présence d'un catalyseur métallique n'est plus nécessaire pour obtenir ces molécules qui présentent un fort intérêt dans le domaine pharmaceutique et dans celui des matériauxThis thesis is part of a very general search for new synthetic eco-friendly methods.In the first part, entitled "Arylation catalyzed by copper nitrate salts aryldiazonium heterocycles", we present our work describing the first example of a Sandmeyer reaction type allowing the formation of a carbon-nitrogen bond (C-N). Our systems can, indeed, arylate nitrogen nucleophiles, essentially pyrazole, from aryldiazoniums electrophiles. The patterns obtained, the arylpyrazoles, are extremely common in the field of life and also in materials. The experimental procedures we use are extremely mild, as they involve only catalytic amounts of copper and acetic acid. Furthermore, this system operates at room temperature without the presence of ligand, base or additive. As a side product of the reaction, nitrogen (N2) is released into the medium but without impacting on the inert atmosphere of the reaction. In the second part, entitled "Synthesis of symmetrical biaryls from aryllithiens in the presence of an iron catalyst", we describe a new iron catalytic system that allows the direct synthesis of symmetrical biaryl derivatives from arylithiens, generated in situ from aryl halides under very mild temperature conditions, using an iron catalyst system in the absence of ligands. The procedure which takes place via an in situ quantitatively generated aryl halide with alkyllithiums exchange, provides an excellent control of reactivity and selectivity.Finally, in the last section entitled "Direct Synthesis of biarylmethanes without a transition metal", we demonstrate a new method for the synthesis of unsymmetrical biarylmethanes in a super basic medium of benzyl ketones, with enolizable iodinated aromatic compounds. Under these conditions, the presence of a metal catalyst is not necessary. The molecules obtained have a strong interest in the pharmaceutical field and in materials
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Trehoux, Alexandre. "Synthèse de complexes binucléaires de fer pour activation réductrice du dioxygène : vers de nouveaux catalyseurs d'oxydation bio-inspirés." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS052/document.
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Ces travaux décrivent la synthèse et l'étude de la réactivité de complexes binucléaires à fer, développés dans le but de mimer l'activité catalytique d'enzymes binucléaires à fer telles que la méthane monooxygénase soluble. Nous avons synthétisé et caractérisé plusieurs complexes binucléaires à fer(III), possédant différents types de groupements (électro-donneurs, électro-attracteurs, donneurs de liaison hydrogène) dans leur seconde sphère de coordination, de façon symétrique ou dissymétrique. Nous avons étudié l'influence de la seconde sphère de coordination de ces différents complexes sur les différents intermédiaires formés (notamment l'intermédiaire µ-peroxo-FeIIIFeIII) lorsque que ces complexes sont exposés au peroxyde d'hydrogène. Nous avons également étudié la capacité de ces différents complexes à catalyser les réactions d'oxydation de différents substrats (sulfures, alcènes et alcanes) par le peroxyde d'hydrogène, en absence et en présence d'eau dans le milieu réactionnel. Une modification intéressante de la chimiosélectivité de la réaction d'oxydation du cyclooctène par le peroxyde d'hydrogène, en présence d'un complexe binucléaire à fer dissymétrique et d'eau dans le milieu réactionnel a été observée. Différentes études d'aspect mécanistique ont été réalisées afin de déterminer l'origine des différents phénomènes observés en catalyse d'oxydationThis work describes the synthesis and the study of the reactivity of diiron complexes, developed in order to mimic the catalytic activity of diiron enzymes such as the soluble methane monooxygenase. We synthesized and characterized several diiron(III) complexes, bearing different types of groups (electron-donating, electron-withdrawing, hydrogen bond donating) in their second coordination sphere, in a symmetrical or non-symmetrical way. We studied the influence of the second coordination sphere of these different complexes over the different intermediates (particularly the µ-peroxo-FeIIIFeIII intermediate) formed by exposing them to hydrogen peroxide. We also studied the ability of these complexes to catalyze the oxidation of various substrates (sulfurs, alkenes, alkanes) by hydrogen peroxide, in absence or in presence of water in the reaction mixture. An interesting modification of chemoselectivity was observed in the case of oxidation of cyclooctene by hydrogen peroxyde, catalyzed by a non-symmetrical diiron complex, in presence of water in the reaction mixture. Several mechanistic studies were performed in order to investigate on the origin of the phenomenons we observed during oxidation catalysis studies
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Baker, Ruletha Deon Goodwin Douglas C. "Roles of an 'inactive' domain in catalase-peroxidase catalysis modulation of active site architecture and function by gene duplication /." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Fall/Dissertations/HARTFIELD-BAKER_RULETNA_19.pdf.
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Halvarsson, Alfred. "Katalytisk omvandling av pyrolysgas i WoodRoll-processen för ökad processtillförlitlighet." Thesis, KTH, Skolan för kemivetenskap (CHE), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-172412.
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This project was a cooperation between the division of Chemical Technology at KTH, Cortus Energy and Haldor Topsoe A/S. The goal was to build up a totally new setup for converting and deoxygenate pyrolysis bio-oil, in order to increase the performance of Cortus Energy’s WoodRoll process. Therefore an iron based catalyst from Haldor Topsoe was used. The building up of the new setup with all reactors and the control panel was a complicated and time-consuming work. This led to an only short time slot for performing experiments, which means that more work needs to be done to get more valuable results. The most important success of this project was to get all the knowledge about the system and to make everything (the whole experimental setup) running properly. However, the sampling system needs to be improved before making further experiments. The experiments which have been done show promising results and that the iron based catalyst was working well for converting the bio-oil. During the two hour long experiment there were not shown any indications of deactivation, when looking at the gas compositions, but the results from temperature programmed oxidation (TPO) show carbon deposition on the catalyst and the BET surface also shows a slight decrease in surface area.
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Luo, Mingliang. "Heterogeneous catalytic oxidation of aqueous phenol using an iron-based catalyst and a magnetic titanium dioxide photocatalyst." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445198.
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MacNair, Alistair James. "Iron-catalysed hydrogenation and hydroboration reactions." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28863.
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Hydrogenation and hydrofunctionalisation reactions provide efficient, sustainable methodologies for the manipulation of synthetic handles and the formation of carbon-heteroatom bonds from readily available starting materials. Traditional hydrogenation methods typically require precious or semi-precious transition metal complexes or finely divided powders. Iron-based catalysts offer several advantages over more traditional ‘noble’ metal systems due to the high abundance, long-term availability, low cost and low toxicity of iron. To date, the most powerful iron-catalysed hydrogenation and hydrofunctionalisation reactions have required either highly air-sensitive iron(0) complexes or iron(II) complexes activated with an extremely reactive, pyrophoric organometallic reagent. An operationally simple and environmentally benign formal hydrogenation protocol has been developed using a simple iron(III) salt and NaBH4; an inexpensive, bench stable, stoichiometric reductant. This reaction has been applied to the reduction of terminal alkenes (22 examples, up to 95% yield) and nitro groups (26 examples, up to 95% yield) in ethanol, under ambient conditions (Scheme A1). Two novel series of structurally related alkoxy-tethered N-heterocyclic carbene (NHC) iron(II) complexes have been developed as catalysts for the regioselective hydroboration of alkenes. Significantly, Markovnikov selective alkene hydroboration with pinacolborane (HBpin) has been controllably achieved for the first time using an iron catalyst (11 examples, 35-90% isolated yield) with up to 37:1 branched:linear selectivity (Scheme A2). anti-Markovnikov selective alkene hydroboration was also achieved using catecholborane (HBcat) and modification of the ligand backbone (6 examples, 44-71% yield). In both cases, ligand design has enabled activator-free iron catalysis.
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O'Connell, Keith. "Biomimetic oxidations using an iron porphyrin catalyst." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/844067/.
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The oxidation of certain 2-alkyl-3-hydroxynaphtho-1,4-quinones, pyrimidines and nucleosides by hydrogen peroxide, catalysed by 5,10,15,20-tetrakis(pentafluorophenyl)porphine iron(ni) chloride is investigated. This catalyst is particularly efficient in the oxidation of the hydroxynaphthoquinones; a proposed epoxide product which was not isolated reacts further to give low yields of a dehydro dimer and an oxoindane carboxylate, which are fully characterised. The mechanisms of formation of these secondary products from the primary epoxide product are discussed. Oxidation of certain pyrimidines and nucleosides using the same catalyst-oxidant combination proceeds in low yield to give unisolatable products, or none at all. Thus, the catalyst-oxidant system is suitable in certain cases as a biomimetic method for the preparation of larger amounts of material to complement in vivo studies of drug metabolism. Kinetic analysis by the initial rates method of the oxidation of hydroxynaphthoquinones using this system is consistent with rapid reaction of the organic substrate with an oxoperferryl intermediate formed in the first and rate-limiting step. In the absence of organic substrate, hydrogen peroxide oxidises the catalyst to a oxoferryl species, probably via the oxoperferryl species. This oxoferryl compound is itself bleached by hydrogen peroxide, probably via oxidation of the porphyrin ring.
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Lepori, Clément. "Complexes de fer(II) et de cobalt(II) de basse coordinance : synthèses, caractérisations et applications en réaction d’hydroamination des alcènes." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS509.
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Les motifs azotés sont présents dans de nombreuses molécules d’intérêts pharmaceutiques. Les méthodes de synthèses traditionnelles de ces motifs vont, par exemple, de la substitution nucléophile d’amines sur des halogénures d’alkyles à de l’amination réductrice des composés carbonylés. Ces méthodes, bien qu’efficaces, nécessitent néanmoins des quantités stœchiométriques de réactifs pour être appliquées et génèrent souvent des quantités importantes de déchets. Un des challenges de la chimie organique moderne consiste à développer de nouvelles méthodes de synthèses de ces motifs plus économiques et plus respectueuses de l’environnement en produisant un taux de déchets le plus faible possible. L’addition directe d’une amine sur une double liaison carbone-carbone non-activée que l’on appelle la réaction d’hydroamination des alcènes est une approche très prometteuse pour le développement d’une méthodologie de synthèse alternative de ces composés. En effet, dans cette réaction, tous les atomes du substrat de départ sont transférés au produit réduisant ainsi considérablement les déchets produits. De plus, les amines et les oléfines employées sont des réactifs relativement bon marché, abondants et variés. Néanmoins, cette transformation a priori simple nécessite généralement l’emploi d’un catalyseur. Dans la littérature, la réaction d’hydroamination des alcènes a été étudiée en utilisant comme catalyseur des complexes de métaux alcalins, alcalino-terreux, de terre-rares et de métaux de transition. Au commencement de ce projet, il n’existait pas d’exemples de réaction d’hydroamination des alcènes mettant en jeu des amines primaires non protégées catalysée par des complexes de fer ou de de cobalt. Dans ce contexte, notre équipe s’est intéressée à la réactivité de complexes de fer(II) et de cobalt(II) de basse valence stabilisés par des ligands de type β-dicétiminate. Ces complexes se sont révélés être d’excellents catalyseurs pour promouvoir la réaction d’hydroamination des amines primaires non protégées liées à des alcènes non activés.Dans un premier temps, les synthèses des complexes de fer(II) et de cobalt(II) alkyles stabilisés par des ligands β-dicétiminates ainsi que leurs applications en réaction de cyclohydroamination des amines primaires non protégées seront présentées. De plus, des études mécanistiques poussées permettront d’éclaircir le mécanisme de la réaction, qui est proposé de passer par une étape élémentaire clé d’insertion 1,2 migratoire aboutissant à la formation d’une liaison carbone-azote.Dans un second temps, les influences des propriétés électroniques et stériques des ligands sur la réactivité en réaction d’hydroamination des alcènes des complexes de fer(II) alkyles seront étudiées. Nous nous attarderons particulièrement sur des complexes stabilisés par des ligands β-dicétiminates dissymétriques ou iminoanilidures. Les données cristallographiques des complexes à l’état solide permettront alors de rationaliser les variations de réactivités de ces différents complexes.Enfin, les complexes de fer(II) et de cobalt(II) synthétisés précédemment seront exploités pour développer de nouvelles réactivités en réactions d’oxydation, d’amination oxydante ou de création de liaison azote-silicium par un couplage déshydrogénantThe nitrogenous units are present in many molecules of pharmaceutical interest. The traditional synthesis methods of these units range, for example, from the nucleophilic substitution of amines on alkyl halides to reductive amination of the carbonyl compounds. These methods, although effective, nevertheless require stoichiometric amounts of reagents to be applied and often generate large amounts of waste. One of the challenges of modern organic chemistry is to develop new methods of synthesizing these more economical and environmentally friendly patterns by producing the lowest waste rate possible. The direct addition of an amine to an unactivated carbon-carbon double bond known as the alkene hydroamination reaction is a very promising approach for the development of an alternative synthesis methodology for these compounds. Indeed, in this reaction, all the atoms of the starting substrate are transferred to the product thus considerably reducing the waste produced. In addition, the amines and olefins employed are relatively inexpensive, abundant and varied reagents. Nevertheless, this simple transformation generally requires the use of a catalyst. In the literature, the hydroamination reaction of alkenes has been studied using alkali metal, alkaline earth, rare earth and transition metal complexes as catalysts. At the beginning of this project there were no examples of the hydroamination reaction of alkenes involving unprotected primary amines catalysed by iron or cobalt complexes. In this context, our team was interested in the reactivity of iron (II) and cobalt (II) complexes of low valence stabilized by β-diketiminate ligands. These complexes have proved to be excellent catalysts for promoting the hydroamination reaction of unprotected primary amines bound to non-activated alkenes.In a first step, the syntheses of the iron (II) and cobalt (II) complexes stabilized by β-diketiminate ligands as well as their applications in cyclohydroamination reaction of the unprotected primary amines will be presented. In addition, advanced mechanistic studies will clarify the mechanism of the reaction, which is proposed to go through a key elementary 1..2 migratory insertion leading to the formation of a carbon-nitrogen bond.In a second step, the influence of the electron and steric properties of the ligands on the reactivity in the hydroamination reaction of the alkenes of the iron (II) alkyl complexes will be studied. We will focus particularly on complexes stabilized by asymmetric β-diketiminate ligands or iminoanilides. The crystallographic data of the solid state complexes will then make it possible to rationalize the variations of reactivities of these various complexes.Finally, the iron (II) and cobalt (II) complexes synthesized above will be exploited to develop new reactivities in oxidation reactions, oxidative amination or the creation of a nitrogen-silicon bond by a dehydrogenating coupling
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Liang, Shunxing. "Catalytic mechanism, multifunctionality and structural design of iron-based metallic glasses." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2019. https://ro.ecu.edu.au/theses/2274.
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Alloys with a well-defined long-range ordered crystalline structure and glasses with a highly disordered amorphous structure as two uncorrelated categories of materials have a long history with a widespread use for different purposes. With the common sense of highly ordered structure in metals/alloys, it is until the 1960s that the first metallic glass (MG, also known as amorphous alloy) has been produced by fast quenching technique to “freeze” their metallic liquid at very high critical cooling rate, realizing glass-like (amorphous/disordered atomic) structure in alloys with extraordinary properties (extreme strength at low temperature, high flexibility at high temperature, etc.) as structural and functional materials. While part of current studies focus on their fundamental and important issues including glass nature and its supercooled liquid state, many application-oriented research endeavors have achieved great successes. Motivated by the pressure of global environmental issues and potential crisis level of fresh water, recently an increasing interest of MGs in attractive catalytic applications has suggested the superior performance of MGs than their crystalline counterparts. Although the application of MGs as catalysts was firstly attempted in almost 40 years ago, their potential value in environmental and energy science has not been recognized until in recent 10 years. As such, studies of catalytic properties of MGs are still very limited and the catalytic mechanism to understand their superior performance is far from easy to achieve. A great effort is still needed for the achievement of the practical catalytic industrialization using massive produced MGs.
Chapter 1 introduces the current challenges of MGs in future development and practical applications, which present as the contradictions between massive production technique and narrow practical application range, between low development as structural materials and high promise as functional materials, and between high catalytic performance and low understanding of mechanism. Accordingly, the significance and innovation of using MGs as functional catalysts will be also described as following: 1) strategies for enhancing catalytic performance of Fe-based MGs without structural change for degradation of organic pollutants; 2) the catalytic application of Fe-based MGs for purifying diversified inorganic contaminants; 3) the potential optimized structure of Fe-based MGs for highly promoting catalytic performance.
Chapter 2 overviews the MGs with structural origin (e.g. short-to-medium-range atomic arrangement with analysis and characterization techniques), glass-forming ability as one of important characteristics for material design, manufacturing methods (i.e. for ribbons, powder and bulk MGs), mechanical and chemical properties, current catalytic properties and applications of MGs (including wastewater treatment, water splitting and fuel cell). The structural heterogeneity in catalysis and strategies to engineer catalytic structure of MGs are also shown in order to develop their future catalytic applications.
Chapter 3 shows the research methods according to different chapters, which contain materials and chemicals, characterization methods, catalytic analysis process, kinetic study methods and other measurements.
Chapter 4 shows the strategies of enhanced catalytic performance of MGs. Fe73.5Si13.5B9Cu1Nb3 MG ribbons are employed for photo-enhanced activation of persulfate (PS), indicating that 100% color removal of malachite green dye can be achieved within 30 min under optimized parameters, and the inclusion of Nb in Fe73.5Si13.5B9Cu1Nb3 MG ribbons promotes enrichment of Si to further improve the surface stability. Yet, the catalytic mechanism of MG ribbons in advanced oxidation processes (AOPs) is not sufficiently understood. As such, Fe78Si9B13 MG ribbons have been applied for the activation of three peroxides: H2O2, PS and peroxymonosulfate (PMS) to investigate catalytic mechanism. The dominant reactive radicals (•OH and/or SO4•−) in AOPs are investigated by competition kinetics using probe reaction. The order of predominant radical generation rate by Fe78Si9B13 under UV-vis irradiation is PS>H2O2>PMS, all with a radical generation rate at least ~2 times higher than other iron-containing materials. The radical evolution mechanism for H2O2, PS and PMS activation has also been investigated. On the other hand, the role of surface to enhance catalytic performance of MGs is suggested. Fe50Ni30P13C7 MG ribbons are found to have the superior corrosion resistance and an effective elimination of surface layer by chemical dealloying can highly promote the catalytic degradation rate of brilliant black BN dye from 20 min to only 10 min, which is attributed to reactivation of surface by chemical dealloying without generating nano-porous structured surface. The reactivation of ribbon surface effectively optimizes active reaction sites and the re-exposure of Fe, Ni and P with zero-valent state forms galvanic cells by atomic clusters leading to the acceleration of catalysis.
Chapter 5 indicates the novel catalytic application of MGs against diversified contaminants. As an advanced alternative of heterogeneous crystalline iron material, low-cost Fe78Si9B13 MG ribbons with mature production by melt spinning is employed in real industrial contaminated water to investigate effective separation of arsenic (As) and reduction of nitrate (NO3−). Fe-based MG ribbons demonstrate attractive high removal rate of As in 30 min with low soluble Fe (1.5 mg/L), which is ascribed to synergistic effect of reduction/adsorption by MG ribbons, precipitation of arsenic sulfide and adsorption of generated iron sulfide. On the other hand, a remarkable sustainability up to 20 reused times of Fe-based MG ribbons for NO3− reduction suggests a promising economic value of MG ribbons in industrial applications. Surface area normalized rate coefficient indicates the superior catalytic capacity of Fe-based MG ribbons compared with other iron materials.
Chapter 6 presents the strategies to engineer catalytic structure correlated to MGs. It is reported that the excellent catalytic behavior in Fe-based MGs goes through a detrimental effect with the partial crystallization but receives a compelling rejuvenation in the full crystallization. Further investigation reveals that multiple crystalline phases with electric potential differences induced by high-temperature annealing facilitate the formation of galvanic cells. The extensively reduced grain boundaries due to grain growth greatly weaken electron trapping and promote inner electron transportation. The relatively homogenous grain-boundary corrosion in the multiphase contributes to well-separated phases after reactions, leading to refreshment of surface active sites, quickly activating H2O2 and rapidly degrading organic pollutants. On the other hand, 3D printing that revolutionizes the way of material manufacturing with functional applications is employed in the manufacturing of an Fe-based MG matrix composite with three-dimensional rhombic dodecahedron microstructure. The 3D-printed porous Fe-based MG matrix composite has been employed into catalytic activation in Fenton-like process and sulfate radical-based reaction. Results demonstrate that extremely high reusability (45 times) is achieved in sulfate radical-based reaction without any apparent efficiency decay. The remarkable catalytic reusability originates from extremely low surface decay. Structural analysis indicates the α-Fe nanocrystals serve as trigger of easy electron transfer but a large amount of α-Fe lead to an inhibitive effect in the MG matrix composite. The overall catalytic ability also demonstrates the excellent catalytic performance of SLM-produced porous Fe-based MG composite in the wastewater remediation.
Chapter 7 concludes the present findings in this thesis and suggests the future challenges and development using MGs as catalysts.
With the investigation of enhanced catalytic performance, catalytic degradation of diversified pollutants and optimization of catalytic structure of Fe-based MGs, this thesis aims to further understand the catalytic mechanism of Fe-based MGs at the atomic size in wastewater treatment, to assess applicability of MGs in practical applications, to provide a novel clue of extending their multifunctional catalytic properties and to suggest the new developing catalyst design with ordered and/or disordered atomic arrangement in the future development.
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Hellgardt, Klaus. "Coprecipitated iron based catalysts for hydrotreating." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243566.
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Müller, Thomas. "C-H Activation by Nickel and Iron Catalysis." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://hdl.handle.net/21.11130/00-1735-0000-0003-C189-8.
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Greenhalgh, Mark David. "Iron-catalysed hydrofunctionalisation of alkenes and alkynes." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/17624.
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The iron-catalysed hydrofunctionalisation of alkenes and alkynes has been developed to give a range of functionalised products with control of regio-, chemo- and stereochemistry. Using a bench-stable iron(II) pre-catalyst, the hydrosilylation, hydroboration, hydrogermylation and hydromagnesiation of alkenes and alkynes has been achieved. Iron-catalysed hydrosilylation, hydroboration and hydrogermylation of terminal, 1,1- and 1,2-disubstituted alkyl and aryl alkenes and alkynes was developed, in which the active iron catalyst was generated in situ (Scheme A1). Alkyl and vinyl silanes and pinacol boronic esters were synthesised in good to excellent yield in the presence of a range of functional groups. Catalyst loadings as low as 0.07 mol% were demonstrated, along with catalyst turn-over frequencies of up to 60 000 mol h−1. The iron-catalysed formal hydrocarboxylation of a range of styrene derivatives has been developed for the synthesis of α-aryl carboxylic acids using carbon dioxide and ethylmagnesium bromide as the stoichiometric hydride source (Scheme A2). Detailed mechanistic studies have shown this reaction proceeds by iron-catalysed hydromagnesiation to give an intermediate benzylic organomagnesium reagent. The nature of the active catalyst and reaction mechanism have been proposed.
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Paul, Uchenna Prince. "Microkinetic Model of Fischer-Tropsch Synthesis on Iron Catalysts." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2535.pdf.
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Belani, Ramesh. "The catalytic decarbonylation of aldehydes using iron porphyrin complexes." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24476.
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The aim of this project was to investigate the use of iron porphyrin complexes as potential homogeneous catalysts for the decarbonylation of aldehydes. Complexes of the type Fe(TPP)L₂ (where L = n-Bu₃P, PPh₃ or piperidine) were prepared and reacted with CO gas, or with aldehydes as sources of CO. Since the loss of coordinated CO from the Fe(TPP)(CO)(n-Bu₃P) complex was more facile, the bis(n-Bu₃P) phosphine system was studied in more detail.
The X-ray structure of FeTPP(n-Bu₃P)₂ Is described, and this includes the first determination of an FeII-P bond distance for a metalloporphyrin.
The study using Fe(TPP)L₂ complexes as decarbonylation catalysts was somewhat hindered by the extreme air-sensitivity of the porphyrin complexes in solution. UV/visible spectroscopy and gas chromatography were used to monitor the decarbonylation reactions. The reaction mixtures were analysed by GC/MS. The decarbonylation reactions were characterised by inconsistent turnover numbers and lack of reproducibility; during the decarbonylation of phenylacetaldehyde, bibenzyl was detected. Such factors are indicative of a free radical mechanism, similar to that proposed earlier for related Ru(II) porphyrin systems.
The carbonylation of FeTPP(n-Bu₃P)₂ by CO gas was of interest with respect to the catalytic reaction, which must involve formation of a carbonyl complex. The reaction,
FeTPP(n-Bu₃P)₂ + CO K [mathematical formula omitted] FeTPP(n-Bu₃P)(CO) + n-Bu₃P was found to have a K value of 0.72 at 29°C, while the temperature dependence of K was studied to obtain the thermodynamic parameters ΔS and ΔH for the equilibrium.Science, Faculty of
Chemistry, Department of
Graduate
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Roudier, Mylène. "Catalyse duale pour une synthèse énantiosélective éco-compatible." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4347.
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Ce mémoire de thèse se concentre sur le développement de réactions multicatalysées impliquant une activation iminium et un transfert d’hydrogène réversible rédox-neutre pour la synthèse de briques moléculaires complexes énantioenrichies à partir de composés 1,3-dicarbonylés et d’alcools allyliques.Une cascade réactionnelle combinant un complexe de fer et une pyrrolidine chirale a été développée pour la préparation d’alcools g-fonctionnalisés énantioenrichis par une approche impliquant économie d’étapes et d’atomes. L’efficacité de cette méthode impliquant une catalyse duale ainsi qu’une étape de rétro-Claisen a été démontré dans la synthèse de fragments clés de produits naturels. Cette méthodologie a ensuite été complétée par une étude mécanistique expérimentale aboutissant à une meilleure compréhension du mécanisme de cette transformation et conduisant également au développement d’une catalyse triple impliquant deux complexes métalliques et un organocatalyseur. Par la suite, une nouvelle approche pour la synthèse de lactones énantioenrichies de taille de cycles moyens a été mise au point. Cette stratégie de synthèse est basée sur une addition-1,4- organocatalysée énantiosélective de Michael, suivie d’une réduction chimiosélective qui engendre une fragmentation de Claisen.Enfin, grâce aux méthodologies développées au cours de cette thèse, la synthèse totale d’un produit naturel, la floribundane B, a été étudiéeThis manuscript is focus on the development of multicatalyzed reactions involving iminium activation and reversible neutral hydrogen transfer reaction for the synthesis of complexe enantioenriched building blocks from allyl alcohols and 1,3-dicarbonyls.An unprecedented cascade catalysis combining an iron catalyst and a pyrrolidine-base catalyst is developed for the preparation of g-fonctionalized enantioenriched alcohols in a formal redox-, atom- and step-economical approach. The efficiency of this method involving a dual catalysis and a retro-Claisen xas further demonstrated in the short synthesis of several key fragments of biologically active natural products or odorant molecule. This methodolgy was then incremented by a experimental mechanistic study allowing a better understanding of the mechanism of this transformation and leading to a new catalytic systeminvolving three different catalysts (iron complex, copper and organocatalyst). Then, we focused on the development of a new synthetic approach to enantioenriched medium-sized lactones. This methodology is based on a 1,4-Michael addition of cycloalkane-1,3-diones to a,b-insaturated aldehydes. Then, a key chemoselective reductively triggered Claisen fragmentation occurred to generate desired lactones in a rapid manner.Finally, thanks to our methodology developed during this thesis, the total synthesis of floribundane B was studied
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Hall, Mark Andrew. "Iron-catalysed cross-coupling and reduction reactions." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.551314.
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Iron nanoparticles of size 6-16 nm have been successfully prepared by the reduction of FeCb with 3-pentylmagnesium bromide in the presence of polyethylene glycol. These nanoparticles show excellent activity in the catalytic dehalogenation of a range of alkyl and aryl halides when used at 5 mol% loadings, if an excess of the Grignard is present to ensure the regeneration of the catalyst. Alkyl halides react to give mixtures of alkane, alkene and homocoupled products, with good selectivity of the alkane product being observed. Aryl halides undergo hydrodehalogenation cleanly and do not undergo homocoupling. A general methodology, previously developed within the group for the cross-coupling of benzyl halides with diarylzinc reagents has been applied to other substrates. This includes 2-halopyridines and N-(bromomethyl)phthalimide, with the former exhibiting slower reaction rates so higher temperatures were required. Surprisingly, in the case of N-(bromomethyl)phthalimide, the coupling reaction was found to proceed without the need for a catalyst. This has been demonstrated for a number of diarylzinc reagents, which resulted in the cross-coupled product being formed in good to excellent yields. Furthermore,. this substrate undergoes cross- coupling with a range of boronic acids via transmetallation to diethylzinc.
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Bayerköhler, Frieder [Verfasser], and Philipp [Akademischer Betreuer] Kurz. "Iron-molybdenum sulphides as proton reduction catalysts." Freiburg : Universität, 2017. http://d-nb.info/1144148901/34.
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Darwish, Moftah. "Iron and ruthenium catalysts for asymmetric synthesis." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/56286/.
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A series of chiral di-, tri- and tetra amine ligands were synthesised from enantiomerically pure 1,2-cyclohexanediamine and 1,2-diphenylethanediamine and, in combination with Ru(II) or Fe(II), employed as asymmetric catalysts in the epoxidation of aromatic alkenes, hydrosilylation of acetophenone, nitro-aldol reaction and asymmetric transfer hydrogenation (ATH) of different ketones. A novel class of tridentate ruthenium catalysts of general structure 239 below were developed. Specifically, a novel class of tridentate ligand was synthesised and a derivative of (R,R)-N-tosyl-1,2-diphenyl-1,2-ethylenediamine ((R,R)-TsDPEN) and was found to provide the best activity and selectivity in reduction reactions with Ru3(CO)12. Reaction conditions were optimised using 239 for the ruthenium-catalysed ATH of a number of ketones. In particular, it was found that the presence of meta-methoxy substituent on the aromatic ring of the substrate yields optimal results under the ATH conditions employed for 48 h (98% conv., 94% ee). Also, aryl ketones substituted at the ortho position were reduced in almost quantitative yield, with enantiomeric excesses greater than 90% in some cases.
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Ikenberry, Myles. "Acid monolayer functionalized iron oxide nanoparticle catalysts." Diss., Kansas State University, 2014. http://hdl.handle.net/2097/17060.
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Doctor of PhilosophyDepartment of Chemical Engineering
Keith L. Hohn
Superparamagnetic iron oxide nanoparticle functionalization is an area of intensely active research, with applications across disciplines such as biomedical science and heterogeneous catalysis. This work demonstrates the functionalization of iron oxide nanoparticles with a quasi-monolayer of 11-sulfoundecanoic acid, 10-phosphono-1-decanesulfonic acid, and 11-aminoundecanoic acid. The carboxylic and phosphonic moieties form bonds to the iron oxide particle core, while the sulfonic acid groups face outward where they are available for catalysis. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectrometry (XPS), and dynamic light scattering (DLS). The sulfonic acid functionalized particles were used to catalyze the hydrolysis of sucrose at 80˚C and starch at 130˚C, showing a higher activity per acid site than the traditional solid acid catalyst Amberlyst-15, and comparing well against results reported in the literature for sulfonic acid functionalized mesoporous silicas. In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic-sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. Between the two sulfonic ligands, the phosphonates produced a more tightly packed monolayer, which corresponded to a higher sulfonic acid loading, lower agglomeration, lower recoverability through application of an external magnetic field, and higher activity per acid site for the hydrolysis of starch. Functionalizations with 11-aminoundecanoic acid resulted in some amine groups binding to the surfaces of iron oxide nanoparticles. This amine binding is commonly ignored in iron oxide nanoparticle syntheses and functionalizations for biomedical and catalytic applications, affecting understandings of surface charge and other material properties.
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Zhu, Kailong. "Iron-catalysed hydride and radical transfer reactions." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28732.
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Iron-catalysed carbonyl reduction, nitro reduction, formal hydroamination, and the radical alkenylation of alkyl halides have been developed. A Simple, easy-to-make, air- and moisture-stable iron(III) amine-bis(phenolate) complex catalysed the hydrosilylation of carbonyl compounds efficiently using triethoxysilane as the reducing agent. The reaction tolerated a wide range of substrates to give the corresponding alcohol products in good to excellent yields after hydrolysis of the hydrosilylated products (Scheme A1). Scheme A1. Iron-Catalysed Hydrosilylation of Carbonyl Compounds. The same catalyst was also an active catalyst for the chemoselective reduction of nitro arenes into corresponding amines using triethoxysilane as reducing agent. The method exhibited excellent chemoselectivity as other reducible functional groups such as halogen, ester, nitrile all kept unchanged during the reaction. This catalytic system was then successfully applied to the formal hydroamination of alkene to give substituted amine in synthetic useful yields under mild condition. The reaction is hypothesised to proceed through a radical intermediate (Scheme A2). Scheme A2. Iron-Catalysed Nitro Reduction and Alkene Formal Hydroamination. Finally, FeCl2-catalysed formal Heck cross-coupling has been developed between alkyl halides and styrenes. The reaction tolerated both electron-rich and electron-neutral substrates to give the products in moderate to excellent yields. Initial studies revealed that the reaction also proceeds through a radical intermediate (Scheme A3). Scheme A3. Iron-Catalysed Formal Heck Cross-Coupling of Functionalised Alkyl Halides.
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Codolà, Duch Zoel. "Iron and iridium molecular complex for water oxidation catalysis." Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/276172.
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Harness light from the sun is one of the 21st century’s major goals towards the substitution of fossil fuels for a renewable source of energy. Sustainable production of highly energetic molecules using sunlight as energy source can provide a recyclable fuel round the clock. In this regard, hydrogen from water is envisioned as an ideal cofactor as this energetic store. Viable production of solar fuels will require the use of earth-abundant based catalysts with high activity and efficiency. Long ago, Nature figured out how to take advantage of the sunlight by converting solar energy into chemical bonds, through water and carbon dioxide. This process has been perfected during millions of years and the development of an artificial system to replicate the natural photosynthesis is extremely challenging. Towards the design of these energy conversion schemes based on sunlight, CO2 and H2O, a key step is the water oxidation. The water oxidation provides the electrons needed for the production of fuel. An efficient catalyst is required to overcome the uphill energy multi-electron transformation. The main objective of this thesis is the design of artificial compounds that efficiently oxidizes water into O2, protons and electrons, as the first step towards the exploitation of the sunlight. The study of these complexes could contribute with valuable information about the oxidation mechanisms taking place during the photosynthesis. The results obtained in this thesis firstly show that readily available iron and iridium complexes can carry out the water oxidation in an efficient manner. Homogeneous high valent metal species (IrV/VI, FeV) are the responsible of this redox process. Furthermore, the characterization of a novel oxo-bridged iron-cerium complex constitutes the first direct observation of a heterodimetallic core in a synthetic water oxidation catalyst. These species can be construed as the closest structural and functional model for the essential heterodimetallic MnV–O–CaII center involved in the water oxidation in PSII.L’aprofitament de la llum solar com a font d’energia és un dels objectius més prometedors alhora de substituir els combustibles fòssils per una font d’energia renovable. La producció sostenible de molècules energètiques mitjançant la llum del sol pot proporcionar un combustible reciclable durant les 24 hores del dia. En aquest aspecte, l’hidrogen obtingut de l’aigua s’entreveu com un cofactor ideal per aquest emmagatzematge energètic. L’ús de catalitzadors basats en materials abundants i amb una activitat i eficiència elevades seran elements indispensables per a la producció viable de combustibles solars. La natura va ser capaç de trobar un mecanisme per aprofitar l’energia solar convertint-la en enllaços químics mitjançant aigua i diòxid de carboni. Aquest procés ha sigut perfeccionat al llarg de milions d’anys i conseqüentment, el desenvolupament de sistemes artificials capaços d’imitar la fotosíntesi natural és extremadament complex. De camí cap al disseny de sistemes per a la conversió d’energia basats en la llum solar, el CO2 i l’H2O, un pas clau és l’etapa d’oxidació de l’aigua. Aquesta etapa proporciona els electrons necessaris per la producció de combustible. La presència d’un catalitzador és necessària per superar aquesta transformació multielectrònica, ja que requereix una elevada energia. L’objectiu principal d’aquesta tesi és el disseny de compostos artificials que oxidin l’aigua i alliberin oxigen, protons i electrons de manera eficient, com a primer pas cap a l’explotació de la llum. L’estudi d’aquests complexos pot contribuir amb informació valuosa sobre el mecanisme d’oxidació que tenen lloc durant la fotosíntesi. Els resultats obtinguts en aquesta tesi mostren que complexos de ferro i iridi fàcilment a l’abat són capaços de catalitzar l’oxidació de l’aigua de manera eficient. Espècies homogènies en alts estat d’oxidació (IrV/VI, FeV) són les responsables de dur a terme aquest procés redox. La caracterització d’un nou dímer de ferro-ceri unit per un pont oxo constitueix la primera observació directa d’un centre heterodimetàl•lic en un catalitzador artificial d’oxidació de l’aigua. Aquesta espècie constitueix el model estructural i funcional més semblant al centre de MnV-O-CaII present en el PSII.
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Wong, Steve. "Catalysis of iron core formation in Escherichia coli bacterioferritin." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/13707.
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Iron is an essential element for almost all life, so iron homeostasis is an important concern for most living organisms. The chemical properties of iron as represented by the low aqueous solubility of ferric iron and the toxicity of hydroxyl radicals it can produce by means of the Fenton reaction make achievement of iron homeostasis both challenging and crucially important. Bacterioferritin (BFR) is a bacterial member of the ferritin family of proteins that stores iron as a microcrystalline ferric hydroxide core of ~2700 iron atoms. This core is surrounded by 24 identical protein subunits, each possessing a dinuclear iron centre that catalyzes the oxidation of Fe²⁺ to Fe³⁺. This structure affords storage, solubility and bioavailability of iron. To improve our incomplete knowledge of the mechanism of iron core formation, the properties of an assembly variant (Glu128Arg/Glu135Arg) and the wild-type of Escherichia coli BFR have been characterized by X-ray crystallography, site-directed mutagenesis, and iron oxidation kinetics. The crystal structure of the variant included two ethylene glycol (EG) molecules adjacent to the dinuclear (ferroxidase) site that catalyzes iron oxidation. One EG resides in the ferroxidase pore that provides a route from the solvent to the ferroxidase site. The other EG resides at the inner surface of the protein where the iron core presumably binds and is surrounded by three acidic residues: Glu47, Asp50, and Asp126. Kinetics studies revealed that Glu47Gln, Asp50Asn and Asp126Asn substitutions in the assembly variant and the wild-type 24-mer retarded iron core formation and that Glu47 is important in iron oxidation at the ferroxidase site whereas Asp50 and Asp126 are important for iron core nucleation. The 3-fold channel, 4-fold channel, B-site channel and the ferroxidase pore of BFR are possible routes of iron entry for core formation, but disruption of each of these sites individually in the 24-mer did not alter the kinetics of iron core formation. The intermediate states of the dinuclear site during iron oxidation are not well defined, but fast formation and decay of a μ-1,2-peroxodiferric intermediate (ƛmax = 650 nm) has been proposed. This intermediate was detected by multi-wavelength stopped flow kinetic analysis of wild-type BFR.
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Edwards, Martin Andrew. "Investigations of iron oxide catalyst systems by electron microscopy." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399150.
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Taylor, Douglas S. C. "Catalysis in the system 1,2-dichloroethane iron(III) chloride." Thesis, University of Glasgow, 2002. http://theses.gla.ac.uk/7015/.
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1,2-Dichloroethane (EDC) plays a major role as an intermediate in the PVC chain and as a feed material for C2 solvent manufacture. Knowledge and understanding at the fundamental level of the role of trace inorganic species present during EDC manufacturing are very limited. The primary aim of this work was therefore to determine the roles of these species. Due to the lack of, and in certain cases contradictory, literature it was important to re-examine the system at its most fundamental levels. The reaction medium in which EDC is produced contains several different organic and inorganic constituents. The most important are 1,2-dichloroethane (present not only as the reaction product but also the solvent), ethane, dichlorine, hydrogen chloride, ethyl chloride, water and iron amongst others (a full description of reaction constituents is provided in chapter 1). The current work has established the presence of [FeCl4]- as the dominant species in solution. Importantly, a precursor to this species has also been identified in dilute and purer/dryer EDC/FeCl3 solutions. This precursor is believed to take the form of a molecular species such as FeCl3.χH2O (χ = 1,2 etc.). The work has also established that the EDC/FeCl3 solution system is inevitably complicated by the presence of FeCl3. This is particularly important when the behaviour of "free" water within the system is examined. The work has established that addition of H2O and/or HCl leads, with time, to the formation of a significant, probably water-related, species in the observed in the infra-red spectrum. A simple model is proposed to account for events occurring at the solid/solution interface.
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Lyu, Jingqing. "Synthesis of Zwitterionic Iron(II) Catalyst For Carbonylative Polymerization." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1618073172322029.
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Swift, Helen R. "Metal ion catalysis of s-nitrosothiol decompositions." Thesis, Durham University, 1996. http://etheses.dur.ac.uk/5337/.
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Most S-nitrosothiols (RSNO) are unstable in aqueous solution and decompose to release nitric oxide. This is catalysed by copper ions. A mechanistic study of NO formation from S-nitrosoglutathione (GSNO), the nitroso derivative of the most abundant thiol in the body, was carried out. This relatively stable S-nitrosothiol decomposed in the presence of reduced glutathione and copper ions. The products were identified as nitric oxide and oxidised glutathione, observed as a complex of copper. The role of reduced glutathione was two fold. Firstly, it reduced Cu(^2+) to produce the active Cu(^+) catalytic species and regenerated the catalyst from the oxidised glutathione complex. Spectrophotometric kinetic measurements, under pseudo first order conditions ([GSNO]»[Cu(^2+)]) showed no conventional order with respect to nitrosothiol. This was attributed to the inconstant concentration of available copper during reaction due to the ability of reduced glutathione to complex Cu(^+) and oxidised glutathione to complex Cu(^2+). An investigation of thiol induced decomposition of GSNO and other more stable nitrosothiols showed the reaction to be first order with respect to thiol and nitrosothiol. The rate equation was determined and has been explained in terms of a radical mechanism involving rate limiting attack of the thiyl radical on the RS-NO bond. The decomposition of S-nitrosothiols via the mercuric ion was also investigated. Reactions were stoichiometric rather than catalytic, and the products determined to be H(_2)NO(_2)(^+) and RSHg(^+). The rate equation was established and the reaction found to be first order in S-nitrosothiol and Hg(^2+). Second order rate constants obtained for a variety of nitrosothiols showed no dependency of the rate of the reaction on the structure of R. A mechanism was proposed involving direct attact of the Hg(^2+) ion on S of the nitroso group, reflecting the high affinity of the metal ion for the sulfur atom. Similarly, an investigation into Ag(^+) mediated S-nitrosothiol decomposition showed the reaction to be stoichiometric. Nitric oxide was not a product of this reaction.
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Weber, Ronald J. "Synthesis of pyridine-bis(imine) iron compounds for future polymerization studies." Click here for download, 2006. http://wwwlib.umi.com/cr/villanova/fullcit?p1432834.
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Aoki, Yuma. "Development of Iron-Catalyzed C-N and C-C Bond Forming Reactions toward Functional Arylamine Synthesis." Kyoto University, 2019. http://hdl.handle.net/2433/242518.
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Greenleaf, William Bruce. "Proton transfer in catalysis by iron and manganese superoxide dismutase." [Gainesville, Fla.] : University of Florida, 2004. http://wwwlib.umi.com/cr/ufl/fullcit?p3136943.
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Thesis (Ph.D.)--University of Florida, 2004.Typescript. Title from title page of source document. Document formatted into pages; contains 94 pages. Includes Vita. Includes bibliographical references.
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Nordgreen, Thomas. "Iron-based materials as tar cracking catalyst in waste gasification." Doctoral thesis, KTH, Kemisk teknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33043.
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The treatment of municipal solid waste (MSW) in Sweden has changed during the past decades due to national legislation and European Union directives. The former landfills have more or less been abandoned in favour of material recycling and waste incineration. On a yearly basis approximately 2.2 million tonnes waste are incinerated in Sweden with heat recovery and to some extent also with electricity generation, though at a low efficiency. It is desirable to alter this utilisation and instead employ MSW as fuel in a fluid bed gasification process. Then electrical energy may be produced at a much higher efficiency. However, MSW contain about 1 % chlorine in the form of ordinary table salt (NaCl) from food scraps. This implies that the tar cracking catalyst, dolomite, which is normally employed in gasification, will suffer from poisoning if applied under such conditions. Then the tar cracking capacity will be reduced or vanish completely with time. Consequently, an alternative catalyst, more resistant to chlorine, is needed. Preliminary research at KTH has indicated that iron in its metallic state may possess tar cracking ability. With this information at hand and participating in the project “Energy from Waste” an experimental campaign was launched. Numerous experiments were conducted using iron as tar cracking catalyst. First iron sinter pellets from LKAB were employed. They were reduced in situ with a stream of hydrogen before they were applied. Later iron-based granules from Höganäs AB were tested. These materials were delivered in the metallic state. In all tests the KTH atmospheric fluidised bed gasifier with a secondary catalytic reactor housing the catalytic material was deployed. Mostly, the applied fuel was birch. The results show that metallic iron possesses an intrinsic ability, almost in the range of dolomite, to crack tars. Calculations indicate that iron may be more resistant to chlorine than dolomite. The exploration of metallic iron’s excellent tar cracking capacity led to the innovative manufacture of an iron catalytic tar cracking filter as well as a general knowledge of its tar cracking capacity. This filter with dual functionality would be a general improvement of the gasification process since it among other things would make the process denser.QC 20110428
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Joorst, Genevieve. "Rhodium as a promoter for an iron Fischer-Tropsch catalyst." Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/5309.
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Bibliography: leaves 111-114.Rhodium was added as a promoter to an iron based catalyst with the view to enhance the formation of oxygenates. The base catalyst 100 Fe / 8.7 Cu 506 K2O / 372 Al2O3 was prepared by impregnation. Three catalysts with varying mass ratios of rhodium to iron (1.3 Rh/100 Fe; 2.4 Rh/100 Fe; 3.9 Rh/100 Fe) were prepared by incipient wetness impregnation fo the base catalyst using rhodium chloride solution.
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Johnson, Tarn C. "Iron and ruthenium catalysts for hydrogen transfer reactions." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/50062/.
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The ruthenium catalysed oxidation of 1-phenylethanol derivatives with the release of hydrogen gas has been studied. A hydrogen acceptor was introduced in an effort to elucidate the rate-determining step of the reaction. The transfer of hydrogen from complex alcohols to simple aldehydes and ketones was pursued as a process for obtaining simple alcohols for fuel cell applications. The Shvo catalyst was identified as being the most efficient catalyst for the oxidation of difficult substrates. A family of iron analogues of the Shvo catalyst were synthesised and studied as precatalysts for the oxidation of alcohols. Catalyst activation was achieved by the removal of a CO ligand using trimethylamine-N-oxide and the oxidation of 1-phenylethanol derivatives with acetone was studied. Simple aldehydes were evaluated as hydrogen acceptors and a novel formylation reaction was discovered. Asymmetric iron analogues of the Shvo catalyst were synthesised and applied to the asymmetric transfer hydrogenation of acetophenone using 5:2 formic acid/triethylamine. The synthesis of further analogues with a tethering group was investigated to improve catalyst stability and enantioselectivity. Novel chiral diamine and amino-alcohol ligands containing 1,2,3-triazole functionalities were developed as ligands for the asymmetric transfer hydrogenation of ketones. Tridentate diaminotriazoles provided the best activity and selectivity in the reduction reactions with Ru3(CO)12.
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House, Matthew Peter. "Selective oxidation of methanol over iron molybdate catalysts." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/56182/.
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The selective oxidation of methanol to formaldehyde over iron molybdate catalysts has been investigated. It has been shown that when Fe2C 3 is present at the surface CO2 and H2 are observed from surface formates, while neighbouring pairs of molybdena sites leads to the production of formaldehyde and water from surface methoxys. When molybdenum sites are isolated then the surface methoxy is stabilised and a direct pathway to CO and H2 is created. On molybdena rich surfaces the production of CO is observed, but as a secondary oxidation product following the linear pathway: CH3OH → CH2O → CO → CO 2, established by varying bed lengths. Catalysts with addition of small amounts of molybdena added to the surface of Fe2O 3, are similar to those with a low bulk ratio of Mo:Fe showing increased activity over Fe2O3. Selectivity is dictated by the presence of isolated or pairs of molybdena sites, which guide the reaction to the primary products of CO and formaldehyde respectively. Structural analysis showed the phases of a-Fe2O3, (X-MoO3 and a-Fe2(MoO4)3, depending on the ratio of the cations present. Molybdenum has been shown to concentrate at the surface of iron molybdates by reactor results from low ratio catalysts, Raman spectroscopy, XP spectroscopy and STEM/EEL spectroscopy. The normal reaction of iron molybdates is via the Mars-van Krevelen mechanism, so tests were made without the presence of gaseous oxygen. The reduction of the surface layer can occur at temperatures as low as 200°C. At temperatures above 250°C diffusion of lattice oxygen to replace the lost surface oxygen can occur, leading to the production of further oxidised products. If the oxidation state of surface molybdenum drops below +6 then formaldehyde selectivity drops markedly, with direct production of CO and secondary production of CO2 observed.
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Wang, Xianqin. "Novel, High Activity Hydroprocessing Catalysts: Iron Group Phosphides." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/26516.
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A series of iron, cobalt and nickel transition metal phosphides was synthesized by means of temperature-programmed reduction (TPR) of the corresponding phosphates. The same materials, Fe₂P, CoP and Ni₂P, were also prepared on a silica (SiO₂) support. The phase purity of these catalysts was established by x-ray diffraction (XRD), and the surface properties were determined by N₂ BET specific surface area (Sg) measurements and CO chemisorption. The activities of the silica-supported catalysts were tested in a three-phase trickle bed reactor for the simultaneous hydrodenitrogenation (HDN) of quinoline and hydrodesulfurization (HDS) of dibenzothiophene using a model liquid feed at realistic conditions (30 atm, 370 °C). The reactivity studies showed that the nickel phosphide (Ni₂P/SiO₂) was the most active of the catalysts. Compared with a commercial Ni-Mo-S/g-Al₂O₃ catalyst at the same conditions, Ni₂P/silica had a substantially higher HDS activity (100 % vs. 76 %) and HDN activity (82 % vs. 38 %).
Because of their good hydrotreating activity, an extensive study of the preparation of silica supported nickel phosphides, Ni₂P/SiO₂, was carried out. The parameters investigated were the phosphorus content and the weight loading of the active phase. The most active composition was found to have a starting synthesis Ni/P ratio close to 1/2, and the best loading of this sample on silica was observed to be 18 wt.%.
Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge spectroscopy (XANES) measurements were employed to determine the structures of the supported samples. The main phase before and after reaction was found to be Ni₂P, but some sulfur was found to be retained after reaction.
A comprehensive scrutiny of the HDN reaction mechanism was also made over the Ni₂P/SiO₂ sample (Ni/P = 1/2) by comparing the HDN activity of a series of piperidine derivatives of different structure. It was found that piperidine adsorption involved an a-H activation and nitrogen removal proceeded mainly by means of a b-H activation though an elimination (E2) mechanism. The relative elimination rates depended on the type and number of b-hydrogen atoms. Elimination of b-H atoms attached to tertiary carbon atoms occurred faster than those attached to secondary carbon atoms. Also, the greater the number of the b-H atoms, the higher the elimination rates. The nature of the adsorbed intermediates was probed by Fourier transform infrared spectroscopy (FTIR) and temperature-programmed desorption (TPD) of the probe molecule, ethylamine. This measurement allowed the determination of the likely steps in the hydrodenitrogenation reaction.Ph. D.
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Misal, Castro Luis Carlos. "Molecular defined iron complexes for catalytic hydrosilylation reactions." Rennes 1, 2012. http://www.theses.fr/2012REN1S106.
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Ce travail de recherche est consacré à la réduction des composés carbonylés tels que les aldéhydes, cétones, imines, esters et acides carboxyliques catalysée par des complexes bien définis du fer. La première partie de ce travail porte sur l'utilisation du système Fe(dppe)₂(H)₂ (1mol %) / NaB(OEt)4 (1mol %) comme catalyseur efficace pour l'hydrosilylation des aldéhydes et cétones avec le PHMS sous activation lumineuse. Dans une seconde partie, une famille de complexes du type [CpFe(CO)₂PR₃]X et CpFe(CO)(X)PR₃ (PR₃ = PPh₃ et PCy₃) a été développée et ces complexes se sont révélés être des catalyseurs actifs pour la réduction des aldéhydes, cétones et esters en alcools dans des conditions sans solvant et sous irradiation lumineuse en présence d'hydrosilanes. D'autre part, les complexes de type {[CpFe(CO)₁₂[Ph₂PCH₂Py-(κP ou κ²P,N)]}X sont efficaces pour l'amination réductrice d'arylaldehydes par hydrosilylation. Nous avons également montré dans la troisième partie du travail que les complexes demi-sandwich [CpFe(CO)₂(IMes)]I étaient d'excellents catalyseurs pour l'hydrosilylation des aldimines et kétimines en amines. Dans une dernière partie de ce travail, l'utilisation de complexes de fer(0) a permis de réduire sélectivement les acides carboxyliques en alcools avec Fe(COD)(CO)₃ comme catalyseur en présence de PhSiH3 comme source d'hydrure sous irradiation UV ou en aldéhydes avec le catalyseur Fe(tPBO)(CO)3 en présence de TMDS comme agent réducteur à 50 °CThis research work deals with the reduction of carbonyl compounds such as aldehydes, ketones, imines, esters and carboxylic acids via hydrosilylation using well-defined iron complexes. First of all, the couple Fe(dppe)₂(H)₂ (1mol %) / NaB(OEt)4 (1mol %) showed to be an efficient catalytic system for the reduction of aldehydes and ketones with PMHS under visible light irradiation. On the other hand, [CpFe(CO)₂PR₃]X and CpFe(CO)(X)PR₃ type complexes (PR₃ = PPh₃ et PCy₃) were good catalysts for the reduction of aldehydes, ketones and esters leading to alcohols in solvent-free conditions under visible light irradiation. {[CpFe(CO)₁₂[Ph₂PCH₂Py-(κP ou κ²P,N)]}X type complexes were effective catalysts for the reductive amination of benzaldehyde derivatives via hydrosilylation. In a third part, we have shown that the piano-stool complex [CpFe(CO)₂(IMes)]I was an excellent catalyst for the direct hydrosilylation of aldimines and ketimines to amines. Finally, in a fourth part, iron(0)-carbonyl complexes could reduce in a specific way free carboxylic acids to alcohols using PhSiH3 as the hydride source and Fe(COD)(CO)3 as the catalyst under UV-irradiation at r. T. Or to aldehydes using TMDS as the reducing agent and Fe(tPBO)(CO)3 as the catalyst at 50 °C
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Pye, Dominic Richard. "Improved and new iron-catalysed cross-coupling reactions." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687060.
Full textAbstract:
Iron-catalysed cross-coupling chemistry is undergoing a renaissance due advantages in cost, toxicity and abundance compared to traditional cross-coupling catalysts. In Chapter 2 it is shown that expensive, synthetically challenging bis-phosphines used in the iron-catalysed cross-coupling of alkyl halides and arylboronic acid pinacol esters can be replaced in many cases with simple iron salts in phosphine-free procedures. More challenging substrates require the use of cheap, widely available bis-phosphines such as dppe (l,2-bis(diphenylphosphino)ethane) or dppp (1,3- bis(diphenylphosphino)propane). An EPR spectrum of the reaction mixture shows the presence of previously reported iron(l) complex [FeBr(dppehL which is the likely resting state in the catalytic cycle. Kinetic studies indicate oxidative addition of the alkyl halide via single-electron transfer to a three-coordinate iron species to be the rate-determining step. Having demonstrated that the key feature for facilitating iron-catalysed Suzuki coupling is the activation of a boronic acid pinacol ester with an organometallic nucleophile, in Chapter 3 it was shown that this form of activation could be applied to bis(pinacolato)diboron, allowing the iron catalysed borylation of alkyl, allyl, benzyl and, to a lesser extent, aryl halides. A unique, low-valent, phosphine-supported iron-boryl complex, [Fe(Bpin)(dpbzhL (pin = pinacolato) was isolated from the reaction of [FeCI₂(dpbz)₂] (l,2-bis(diphenylphosphino)benzene) and Li[B₂pin₂(¹Bu)], however this complex failed to react in stoichiometric reactions with 1- bromobutane, reflecting the finding that excess phosphine greatly retards the rate of ironcatalysed borylation. The uniqueness of these low-valent iron-boryl intermediates provided an opportunity to investigate new forms of catalysis based on these complexes. Chapter 4 describes attempts to catalyse the boryl/electrophile difunctionalisation of styrene using Li[B₂pin₂(¹Bu)) and iron precatalysts. It was found that stoichiometric iron is capable of mediating the boryl protonation of styrene; however attempts to trap the organometallic intermediate proved fruitless, and deuterium labelling studies were unable to determine the origin of the a-hydrogen in the resultant product. In order to expand the utility of iron-catalysed cross-coupling, in Chapter 5 attempts to couple electrophiles ·derived from enantiomerically pure l,2-amino alcohols are described. A range of electrophiles including l,2-amino halides, cyclic sulfamidates, oxazolidinones, and oxazolinethiones were screened for activity in iron- and nickel-catalysed cross-coupling; however none of these furnished the desired products.