Segui questo link per vedere altri tipi di pubblicazioni sul tema: Catalysis.
Tesi sul tema "Catalysis"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Catalysis".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Liu, Hongying. "Syntheses, structures, and catalysis of polynuclear metal complexes". Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/30561.
Testo completo
2
Cunje, Alwin. "Noble gases and catalysis". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0012/NQ59125.pdf.
Testo completo
3
Clarke, Richard John. "Mesopore immobilised bis(oxazoline) catalysts for enantioselective catalysis". Thesis, University of Birmingham, 2003. http://etheses.bham.ac.uk//id/eprint/3578/.
Testo completoAbstract (sommario):
Mesoporous silica materials have the potential to replace many conventional silicas for uses such as supports for heterogeneous catalysis and absorbents. The large pore size and high surface area make them ideal for supporting bulky organometallic catalysts for enantioselective reactions. We have immobilised chiral bis(oxazoline) metal complexes onto the surfaces of some of these versatile supports (MCM-41 and MCM-48) via different tethering strategies. The resulting heterogeneous catalysts were shown to be highly active in the enantioselective cyclopropanation of styrene with ethyl diazoacetate.
4
Rosenthal, Daniel Jay. "Estimating the acid site density of silica-alumina by infrared spectroscopy using a selective reactant poison". Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/10222.
Testo completo
5
Richardson, John Michael. "Distinguishing between surface and solution catalysis for palladium catalyzed C-C coupling reactions: use of selective poisons". Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22704.
Testo completoAbstract (sommario):
This work focuses on understanding the heterogeneous/homogeneous nature of the catalytic species for a variety of immobilized metal precatalysts used for C-C coupling reactions. These precatalysts include: (i) tethered organometallic palladium pincer complexes, (ii) an encapsulated small molecule palladium complex in a polymer matrix, (iii) mercapto-modified mesoporous silica metalated with palladium acetate, and (iv) amino-functionalized mesoporous silicas metalated with Ni(II). As part of this investigation, the use of metal scavengers as selective poisons of homogeneous catalysis is introduced and investigated as a test for distinguishing heterogeneous from homogeneous catalysis. The premise of this test is that insoluble materials functionalized with metal binding sites can be used to selectively remove soluble metal, but will not interfere with catalysis from immobilized metal. In this way the test can definitely distinguish between surface and solution catalysis of immobilized metal precatalysts.
This work investigates three different C-C coupling reactions catalyzed by the immobilized metal precatalysts mentioned above. These reactions include the Heck, Suzuki, and Kumada reactions. In all cases it is found that catalysis is solely from leached metal. Three different metal scavenging materials are presented as selective poisons that can be used to determine solution vs. surface catalysis. These selective poisons include poly(vinylpyridine), QuadrapureTM TU, and thiol-functionalized mesoporous silica. The results are contrasted against the current understanding of this field of research and subtleties of tests for distinguishing homogeneous from heterogeneous catalysis are presented and discussed.
6
Reddy, P. K. "Exploration of catalysts and catalysis under near working conditions". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2018. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4577.
Testo completo
7
Beckler, Robert Kendall. "Polynuclear metal complexes as model mixed oxide catalysts". Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/11897.
Testo completo
8
Damian, Karen Serena. "Pd catalysed synthesis of phosphines for homogeneous catalysis". Thesis, St Andrews, 2009. http://hdl.handle.net/10023/907.
Testo completo
9
Jenkins, Patrick L. "Electrochemical and catalytic investigation of catalysis by gold". Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/56012/.
Testo completoAbstract (sommario):
The performance of gold/graphite as an oxidation catalyst has been investigated in an electrochemical cell (electrooxidation at ambient temperature and pressure) and in a high pressure reactor (conventional catalytic oxidation typically at 3 bar and 333 K). A range of gold/graphite catalysts having various metal loadings were prepared and characterised by cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The technique of lead underpotential deposition (Pdupd) was used to reveal the presence of {111}, {100}, and {110} facets in the surfaces of the gold microcrystals. Oxidation of 1-propanol to propionic acid, of 2-propanol to acetone, and of glycerol to wide range of products was investigated both in electrooxidation and in conventional catalytic oxidation. Variation of the surface morphology of the gold active phase was achieved by (i) thermal annealing and sintering of the catalysts under air and under hydrogen, (ii) deposition of bismuth onto the gold surface, and (iii) preparation of further catalysts in which Au was deposited onto Pt/graphite. Conventional catalytic oxidation of the 1-propanol, 2-propanol, and glycerol over the full range of gold-containing catalysts is reported. Variations in catalyst structure were accompanied by changes in activity and selectivity, indicating that these reactions were indeed structure sensitive. However, few correlations of these experimental outcomes with the surface states identified by the voltammetric techniques were evident.
10
Xu, Jiahui. "Catalytic properties of nano ceria in heterogeneous catalysis". Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:02e68ff9-ce28-475a-bd08-6b60bcda64e7.
Testo completoAbstract (sommario):
There have been many applications of cerium oxide in oxidation catalysis but the understanding of its role in catalysis is rather limited. This research is concerned with the use of nano-size cerium oxide in methane steam reforming reaction. It is found that addition of cerium oxide to the commercial supported Ni catalysts can dramatically reduce the undesirable carbon deposition (through surface oxidation), which is thermodynamically favorable under low steam conditions. In order to understanding the fundamental role of oxidation activity of the cerium oxide, different sizes of nano-crystallined cerium oxides have been carefully prepared by micro-emulsion technique. Their reactivity is clearly shown to be size dependent. We found that ceria particle sizes of lower than 5.1 nm are able to activate molecular oxygen, which accounts for the unprecedentedly reported critical size effect on oxidation. Characterizations by EPR, XPS, TPR suggest that a substantially large quantity of adsorbed oxygen species (O2 -) is preferentially formed in the small size ceria from air. Also, it is found that the oxygen vacancies are formed in the interface of metal and oxide, and the strength of the metal oxide interaction may influence the formation of the efficient oxygen vacancies, which are responsible for the adsorbed surface oxygen.
11
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.
Testo completoAbstract (sommario):
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.
12
Guo, Chris. "Alkane Oxidation Catalysis by Homogeneous and Heterogeneous Catalyst". Thesis, The University of Sydney, 2005. http://hdl.handle.net/2123/622.
Testo completoAbstract (sommario):
Abstract Cobalt-based complexes are widely used in industry and organic synthesis as catalysts for the oxidation of hydrocarbons. The Co/Mn/Br (known as "CAB system") catalyst system is effective for the oxidation of toluene. The Co/Mn/Br/Zr catalyst system is powerful for the oxidation of p-xylene, but not for the oxidation of toluene. [Co3O(OAc)5(OH)(py)3][PF6] (Co 3+ trimer 5) is more effective than [Co3O(OAc)6(py)3][PF6] (Co 3+ trimer 6) as a catalyst in the CAB catalyst system. Higher temperatures favour the oxidation of toluene. Zr 4+ does not enhance the oxidation of toluene. Zr 4+ could inhibit the oxidation of toluene in the combination of Co/Br/Zr, Co/Mn/Zr or Co/Zr. NHPI enhances the formation of benzyl alcohol, but the formation of other by-products is a problem for industrial processes. Complex(es) between cobalt, manganese and zirconium might be formed during the catalytic reaction. However, attempts at the preparation of complexes consisting of Co/Zr or Mn/Zr or Co3ZrP or Co8Zr4 clusters failed. The oxidation of cyclohexane to cyclohexanone and cyclohexanol is of great industrial significance. For the homogeneous catalysis at 50 o C and 3 bar N2 pressure, the activity order is: Mn(OAc)3 �2H2O > Mn12O12 cluster > Co 3+ trimer 6 > [Co3O(OAc)3(OH)2(py)5][PF6]2 (Co 3+ trimer 3) > Co 3+ trimer 5 > Co(OAc)2 �4H2O > [Co2(OAc)3(OH)2(py)4][PF6]-asym (Co dimerasym) > [Co2(OAc)3(OH)2(py)4][PF6]-sym (Co dimersym); whereas [Mn2CoO(OAc)6(py)3]�HOAc (Mn2Co complex) and zirconium(IV) acetate hydroxide showed almost no activity under these conditions. But at 120 o C and 3 bar N2 pressure, the activity order is changed to: Co dimerasym > Co(OAc)2 �4H2O > Co trimer 3 and Mn(OAc)3 �2H2O > Co 3+ trimer 6 > Mn2Co complex > Co 3+ trimer 5 > Co dimersym > Mn12O12 cluster. The molar ratio of the products was close to cyclohexanol/cyclohexanone=2/1. Mn(II) acetate and zirconium(IV) acetate hydroxide showed almost no activity under these conditions. Among those cobalt dimers and trimers, only the cobalt dimerasym survived after the stability tests, this means that [Co2(OAc)3(OH)2(py)4][PF6]-asym might be the active form for cobalt(II) acetate in the CAB system. Metal-substituted (silico)aluminophosphate-5 molecular sieves (MeAPO-5 and MeSAPO-5) are important heterogeneous catalysts for the oxidation of cyclohexane. The preparation of MeAPO-5 and MeSAPO-5 and their catalytic activities were studied. Pure MeAPO-5 and MeSAPO-5 are obtained and characterised. Four new pairs of bimetal-substituted MeAPO-5 and MeSAPO-5(CoZr, MnZr, CrZr and MnCo) were prepared successfully. Two novel trimetal-subtituted MeAPO-5 and MeSAPO-5 (MnCoZr) are reported here. Improved methods for the preparation of four monometal-substituted MeAPO-5 (Cr, Co, Mn and Zr) and for CoCe(S)APO-5 and CrCe(S)APO-5 are reported. Novel combinational mixing conditions for the formation of gel mixtures for Me(S)APO-5 syntheses have been developed. For the oxidation of cyclohexane by TBHP catalysed by MeAPO-5 and MeSAPO-5 materials, CrZrSAPO-5 is the only active MeSAPO-5 catalyst among those materials tested under conditions of refluxing in cyclohexane. Of the MeAPO-5 materials tested, whereas CrCeSAPO-5 has very little activity, CrZrAPO-5 and CrCeAPO-5 are very active catalysts under conditions of refluxing in cyclohexane. MnCoAPO-5, MnZrAPO-5 and CrAPO-5 are also active. When Cr is in the catalyst system, the product distribution is always cyclohexanone/cyclohexanol equals 2-3)/1, compared with 1/2 for other catalysts. For MeAPO-5, the activity at 150 o C and 10 bar N2 pressure is: CrZrAPO-5 > CrCeAPO-5 > CoZrAPO-5. For MeAPO-5 and MeSAPO-5, at 150 o C and 13 bar N2 pressure, the selectivity towards cyclohexanone is: CrZrAPO-5 > CrZrSAPO-5 > CrCeAPO-5 > CrAPO-5 > MnCoAPO-5 > MnZrAPO-5; and the selectivity towards cyclohexanol is: MnZrAPO-5 > CrZrAPO-5 > MnCoAPO-5 > CrZrSAPO-5 > CrCeAPO-5 > CrAPO-5. Overall the selectivity towards the oxidation of cyclohexane is: CrZrAPO-5 > CrZrSAPO-5 > CrCeAPO-5 > CrAPO-5 > MnCoAPO-5 > MnZrAPO-5. The amount of water in the system can affect the performance of CrCeAPO-5, but has almost no effect on CrZrAPO-5. Metal leaching is another concern in potential industrial applications of MeAPO-5 and MeSAPO-5 catalysts. The heterogeneous catalysts prepared in the present work showed very little metal leaching. This feature, coupled with the good selectivities and effectivities, makes them potentially very useful.
13
Guo, Chris. "Alkane Oxidation Catalysis by Homogeneous and Heterogeneous Catalyst". University of Sydney. Chemistry, 2005. http://hdl.handle.net/2123/622.
Testo completoAbstract (sommario):
Abstract Cobalt-based complexes are widely used in industry and organic synthesis as catalysts for the oxidation of hydrocarbons. The Co/Mn/Br (known as "CAB system") catalyst system is effective for the oxidation of toluene. The Co/Mn/Br/Zr catalyst system is powerful for the oxidation of p-xylene, but not for the oxidation of toluene. [Co3O(OAc)5(OH)(py)3][PF6] (Co 3+ trimer 5) is more effective than [Co3O(OAc)6(py)3][PF6] (Co 3+ trimer 6) as a catalyst in the CAB catalyst system. Higher temperatures favour the oxidation of toluene. Zr 4+ does not enhance the oxidation of toluene. Zr 4+ could inhibit the oxidation of toluene in the combination of Co/Br/Zr, Co/Mn/Zr or Co/Zr. NHPI enhances the formation of benzyl alcohol, but the formation of other by-products is a problem for industrial processes. Complex(es) between cobalt, manganese and zirconium might be formed during the catalytic reaction. However, attempts at the preparation of complexes consisting of Co/Zr or Mn/Zr or Co3ZrP or Co8Zr4 clusters failed. The oxidation of cyclohexane to cyclohexanone and cyclohexanol is of great industrial significance. For the homogeneous catalysis at 50 o C and 3 bar N2 pressure, the activity order is: Mn(OAc)3 �2H2O > Mn12O12 cluster > Co 3+ trimer 6 > [Co3O(OAc)3(OH)2(py)5][PF6]2 (Co 3+ trimer 3) > Co 3+ trimer 5 > Co(OAc)2 �4H2O > [Co2(OAc)3(OH)2(py)4][PF6]-asym (Co dimerasym) > [Co2(OAc)3(OH)2(py)4][PF6]-sym (Co dimersym); whereas [Mn2CoO(OAc)6(py)3]�HOAc (Mn2Co complex) and zirconium(IV) acetate hydroxide showed almost no activity under these conditions. But at 120 o C and 3 bar N2 pressure, the activity order is changed to: Co dimerasym > Co(OAc)2 �4H2O > Co trimer 3 and Mn(OAc)3 �2H2O > Co 3+ trimer 6 > Mn2Co complex > Co 3+ trimer 5 > Co dimersym > Mn12O12 cluster. The molar ratio of the products was close to cyclohexanol/cyclohexanone=2/1. Mn(II) acetate and zirconium(IV) acetate hydroxide showed almost no activity under these conditions. Among those cobalt dimers and trimers, only the cobalt dimerasym survived after the stability tests, this means that [Co2(OAc)3(OH)2(py)4][PF6]-asym might be the active form for cobalt(II) acetate in the CAB system. Metal-substituted (silico)aluminophosphate-5 molecular sieves (MeAPO-5 and MeSAPO-5) are important heterogeneous catalysts for the oxidation of cyclohexane. The preparation of MeAPO-5 and MeSAPO-5 and their catalytic activities were studied. Pure MeAPO-5 and MeSAPO-5 are obtained and characterised. Four new pairs of bimetal-substituted MeAPO-5 and MeSAPO-5(CoZr, MnZr, CrZr and MnCo) were prepared successfully. Two novel trimetal-subtituted MeAPO-5 and MeSAPO-5 (MnCoZr) are reported here. Improved methods for the preparation of four monometal-substituted MeAPO-5 (Cr, Co, Mn and Zr) and for CoCe(S)APO-5 and CrCe(S)APO-5 are reported. Novel combinational mixing conditions for the formation of gel mixtures for Me(S)APO-5 syntheses have been developed. For the oxidation of cyclohexane by TBHP catalysed by MeAPO-5 and MeSAPO-5 materials, CrZrSAPO-5 is the only active MeSAPO-5 catalyst among those materials tested under conditions of refluxing in cyclohexane. Of the MeAPO-5 materials tested, whereas CrCeSAPO-5 has very little activity, CrZrAPO-5 and CrCeAPO-5 are very active catalysts under conditions of refluxing in cyclohexane. MnCoAPO-5, MnZrAPO-5 and CrAPO-5 are also active. When Cr is in the catalyst system, the product distribution is always cyclohexanone/cyclohexanol equals 2-3)/1, compared with 1/2 for other catalysts. For MeAPO-5, the activity at 150 o C and 10 bar N2 pressure is: CrZrAPO-5 > CrCeAPO-5 > CoZrAPO-5. For MeAPO-5 and MeSAPO-5, at 150 o C and 13 bar N2 pressure, the selectivity towards cyclohexanone is: CrZrAPO-5 > CrZrSAPO-5 > CrCeAPO-5 > CrAPO-5 > MnCoAPO-5 > MnZrAPO-5; and the selectivity towards cyclohexanol is: MnZrAPO-5 > CrZrAPO-5 > MnCoAPO-5 > CrZrSAPO-5 > CrCeAPO-5 > CrAPO-5. Overall the selectivity towards the oxidation of cyclohexane is: CrZrAPO-5 > CrZrSAPO-5 > CrCeAPO-5 > CrAPO-5 > MnCoAPO-5 > MnZrAPO-5. The amount of water in the system can affect the performance of CrCeAPO-5, but has almost no effect on CrZrAPO-5. Metal leaching is another concern in potential industrial applications of MeAPO-5 and MeSAPO-5 catalysts. The heterogeneous catalysts prepared in the present work showed very little metal leaching. This feature, coupled with the good selectivities and effectivities, makes them potentially very useful.
14
Sonqishe, Thantaswa Millecent. "Treatment of brines using commercial zeolites and zeolites synthesized from fly ash derivative". Thesis, University of the Western Cape, 2008. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6127_1297842299.
Testo completoAbstract (sommario):
The objectives of this project was to ameroliate two waste materials, namely Acid Mine Drainage and Fly Ash and recover the solid residues for conversion into an adsorbent to treat brine. The solid residues were then converted into zeolite P through low temperature hydrothermal treatment. The adsorption capacity of the solid residues, zeolite P derived from the solid residues was compared to the commercial zeolite Y and fresh Arnot fly ash. The quality of the resulting water was assessed using different analytical methods before the reaction with adsorbents and after the reaction and a comparison was done based on the removal efficiency of elements Zeolite P from solid residues was successfully synthesized as confirmed by XRD, BET and FTIR. Brine treatment with fly ash, solid residues, zeolite P and commercial zeolite Y adsorbents was done concentration on the following major elements Na, K, Mg, Ca and Si. Zeolite P had higher or similar removal efficiency that the commercial zeolite Y for the following elements K, Ca and Mg. Fly ash is the only adsorbent that managed to reduce the concentration of Na in brine and also had a good removal efficiency of Mg. Si leached out of all the adsorbents which could be ascribed to Si being the major component of these adsorbents which could indicate some dissolution of these adsorbents under the conditions tested. Overall, zeolite P did not completely remove the major elements, especially for Na, but did result in a cleaner waste stream which would improve brine processing.
15
Venable, Margaret Hamm. "Syntheses, structures and support interactions of potential metal oxide catalyst precursors". Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/26940.
Testo completo
16
Linganiso, Linda Zikhona. "Adsorption studies on supported gold catalysts using temperature programmed desorption (TPD)". Thesis, Wits University, 2007. http://hdl.handle.net/10539/20167.
Testo completo
17
Boich, Kenneth Paul. "Catalysis". The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1328726768.
Testo completo
18
Nees, Mary Barton. "Catalysis". Digital Commons @ East Tennessee State University, 2007. https://dc.etsu.edu/etd/2047.
Testo completoAbstract (sommario):
The artist discusses the process of discovery that led to her Master of Fine Arts exhibition at Slocumb Galleries, East Tennessee State University, from March 19 to 23, 2007. Investigations in printmaking, mixed media, and symbol are highlighted. The work for the thesis show consists of nineteen, 30" hand pulled works on paper. All works are oriented vertically and floated in the frame. Of this collection, thirteen are monotypes, four are collographs, and one is a collage. Insertions include intaglio, brayer marking, encaustic wax, paper, oil paint, pen, and sumi ink. Topics included are the artist's thinking into the nature of creativity and the potential for art to speak into culture. The artist discusses some of her own process in this discovery exploring landscape, symbol, and abstraction. Included are a few contextual earlier landscapes of the artist's, some examples of discovery, and a catalogue of the final thesis show.
19
Beach, Nicholas James. "Metathesis Catalysts in Tandem Catalysis: Methods and Mechanisms for Transformation". Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22731.
Testo completoAbstract (sommario):
The ever-worsening environmental crisis has stimulated development of less wasteful “green” technologies. To this end, tandem catalysis enables multiple catalytic cycles to be performed within a single reaction vessel, thereby eliminating intermediate processing steps and reducing solvent waste. Assisted tandem catalysis employs suitable chemical triggers to transform the initial catalyst into new species, thereby providing a mechanism for “switching on” secondary catalytic activity.
This thesis demonstrates the importance of highly productive secondary catalysts through a comparative hydrogenation study involving prominent hydrogenation catalysts of tandem ring-opening metathesis polymerization (ROMP)-hydrogenation, of which hydridocarbonyl species were proved superior. This thesis illuminates optimal routes to hydridocarbonyls under conditions relevant to our ROMP-hydrogenation protocol, using Grubbs benzylidenes as isolable proxies for ROMP-propagating alkylidene species. Analogous studies of ruthenium methylidenes and ethoxylidenes illuminate optimal routes to hydridocarbonyls following ring-closing metathesis (RCM) and metathesis quenching, respectively. The formation of unexpected side products using aggressive chemical triggers is also discussed, and emphasizes the need for cautious design of the post-metathesis trigger phase.
20
Smallwood, Keith. "Catalysis and photocatalysis by platinized titanium dioxide and other catalysts". Thesis, University of Nottingham, 1993. http://eprints.nottingham.ac.uk/12591/.
Testo completoAbstract (sommario):
The gas-phase, thermal hydrogenations of propene and cyclopropane over various titania-supported metal catalysts have been investigated. Catalysts were prepared either by a photodeposition or a thermal reduction method. Absolute initial hydrogenation rates were calculated from total gas pressure vs time measurements. The activities of all catalysts were found to be very dependent upon catalyst state, as modified by reductive or oxidative pretreatments. These results are discussed in terms of reversible strong metal-support interactions, initiated via hydrogen spillover. For 0.5 %mass Pt on Ti02, the order of reaction with respect. to hydrocarbon was 0.5. An adsorption mechanism involving the alkylidene species is proposed as one possible explanation of this result. A negative order of reaction with respect to hydrogen was recorded. A Langmuir-Hinshelwood mechanism, involving competitive adsorption of hydrocarbon and hydrogen at supported metal sites, is proposed. Differences in behaviour between catalysts prepared by photodeposition and the thermally-prepared catalyst were observed during the hydrogenation studies. These include different apparent activation energies, maximum reaction rates at differing propene: hydrogen ratios and irreversible degradation of all photodeposited catalysts during cyclopropane hydrogenation. These differences are taken as being strongly indicative of differences in supported metal morphologies, arising as a consequence of the preparative routes employed. Temperature programmed desorption and scanning electron microscopy studies were undertaken in an attempt to establish and characterise these potential morphological differences. Although the results of these studies were, at best, inconclusive, the possible nature of such supported metal morphological differences is discussed on the basis of available evidence generated within this and other, similar, studies. The liquid-phase photocatalytic dehydrogenation of propan-2-ol, using the same catalysts, was also briefly investigated. Variations in measured activation energies suggest that photodeposited catalysts in the 'as prepared' state are contaminated with variable levels of impurity residues, particularly chloride ions.
21
Carter, Christabel Anne. "Asymmetric phase transfer catalysis : towards catalysts with a chiral anion". Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399654.
Testo completo
22
Monti, Chiara. "Development of new catalysts for asymmetric catalysis via combinatorial chemistry". Thesis, University of Sheffield, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398589.
Testo completo
23
Konrad, Tina Maria. "Chiral phanephos derived catalysts and their application in asymmetric catalysis". Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/4499.
Testo completoAbstract (sommario):
The research presented in this thesis is a project funded by the EU-network of the Marie Curie project NANO-HOST in collaboration with partner institutes. The aims of this network are to develop innovative methods for the preparation, recovery and reuse of single-site, nanostructured catalytic materials, and further on apply them in combination with specifically engineered reactors for a sustainable production process for making high value fine chemicals. One part of this project was to prepare chiral diphosphine ligands and their complexes for currently challenging reactions, such as asymmetric carbonylations (homogeneous catalysis). Catalytic studies of these chiral diphosphine ligands were carried out in asymmetric hydroxy-and alkoxy-carbonylations and hydrogenation reactions. The second part of this project was the heterogenisation of these chiral homogeneous complexes through collaborations with the network partners and furthermore their catalytic behavior was studied.
24
Paterson, A. James. "Exploitation of synergy in oxidation catalysis with bimetallic aluminophosphate catalysts". Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/192867/.
Testo completoAbstract (sommario):
A series of novel bimetallic aluminophosphate catalysts were prepared with the simultaneous isomorphous substitution of cobalt (III) and manganese (III) for aluminium (III) and titanium (IV) replacing phosphorus (V). By substituting simultaneously for both Al (III) and P (V) in the ordered microporous aluminophosphate AlPO-5, the potential for catalytic application as either a solidacid or redox catalyst is produced. The bimetallic hydrothermal synthesis produced a phase pure and highly crystalline microporous catalyst which displayed properties not seen in monometallic AlPO-5 materials. These catalysts were fully characterized by physical, diffraction, spectroscopic and electrochemical techniques including powder X-ray diffraction, diffuse reflectance UV/Visible spectroscopy, cyclic voltammetry, extended X-ray absorption fine structure, X-ray absorption near edge spectra, scanning electron microscopy and surface/elemental (BET and ICP) methods. A significant change was observed when two metals were combined in the same structural framework, leading to an enhancement in the catalyst performance over the monometallic analogues. EXAFS indicated a change in the relative bond lengths, thought to be as a result of compensation in the structural distortion, similarly UV/Visible spectroscopy highlighted a change in the tetrahedral environment around the titanium centre when in combination with a redox metal. These catalysts were tested for the ammoximation of cyclohexanone using benign reagents to produce cyclohexanone oxime, a vital precursor in the production of nylon-6. Currently produced through hazardous processes, the ammoximation of cyclohexanone with metal substituted catalysts provides a more environmentally favourable solution. The use of a redox metal such as cobalt (III) in combination with titanium (IV) was shown to facilitate higher catalytic conversions compared with the monometallic AlPO-5 analogues while maintaining the high oxime selectivity. Similarly the epoxidation of cyclohexene with the solid oxidant acetylperoxyborate (APB) indicated a significantly higher conversion with the CoIIITiIVAlPO-5 catalyst. The substitution of two metals to replace both aluminium and phosphorus sites clearly influences and modifies the nature of the active site and provides an enhanced catalytic performance for ammoximation and epoxidation reactions. This synergy exerted through bimetallic substitution provides an important alternative approach to academic and industrial application of metal substitution within heterogeneous catalysis
25
Barakat, Khaldoon A. Cundari Thomas R. "Computational studies of selected ruthenium catalysis reactions". [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-5203.
Testo completo
26
Iniesta, Beteta Ester. "Supramolecular Catalytic Systems: Synthesis, Characterization and Application in Catalysis". Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/671551.
Testo completoAbstract (sommario):
Aquesta tesi doctoral abasta el disseny i el desenvolupament de catalitzadors supramoleculars derivats de metalls de transició per a la seva aplicació com a catalitzadors en transformacions d'interès.
La primera part d'aquesta tesi doctoral està centrada en el desenvolupament de catalitzadors de coure(I) regulats supramolecularment i la seva aplicació en reaccions d'inserció d'espècies carbèniques metàl·liques a enllaços O–H, generant derivats α-alquil/aril-α-alcoxi/ariloxi. S’abordà el disseny, preparació, caracterització i aplicació dels catalitzadors de coure(I) derivats de lligands bisoxazolina. Aquests estudis van demostrar que l'activitat catalítica es podia modular amb l'ús de molècules externes (agents de regulació), que interaccionaven amb la cadena polioxietilènica del lligand (centre de regulació) a través d'interaccions supramoleculars de tipus ió-dipol. L'eficiència d'aquesta aproximació es demostrà en reaccions d’inserció de carbens metàl·lics sobre alcohols estructuralment diversos (derivats cicloalquílics, alquílics i arílics). Aquesta metodologia es va utilitzar també per a preparar intermedis sintètics avançats de compostos amb rellevància biològica.
La segona part d'aquesta tesi doctoral està centrada en l'ús d'interaccions de tipus halogen per formar l'esquelet de complexos metàl·lics. Es descriu la síntesis de nous complexos supramoleculars de platí(II) i pal·ladi(II) mitjançant l'assemblatge de dos blocs constituents que contenen fosfines com a grups coordinants, així com grups capaços de formar enllaços de tipus halogen. Es va caracteritzar en dissolució i a l’estat sòlid un conjunt de complexos estructuralment diversos de platí(II) i pal·ladi(II) derivats de difosfines (supramoleculars). Es va realitzar un ampli estudi dels intermedis de reacció que van conduir als complexos de platí(II) finals. Es proposa una racionalització mecanística de la formació dels complexos de platí(II) finals. El complex XBPhos-Pt va resultar ser inactiu en reaccions de ciclació d’enins i d’hidrofenilació de l’etilè. Es presenten estratègies d’activació del complex XBPhos-Pt i anàlegs per a noves transformacions químiques.Esta tesis doctoral abarca el diseño y desarrollo de catalizadores supramoleculares derivados de complejos de metales de transición para su aplicación como catalizadores en transformaciones de interés. La primera parte de esta tesis doctoral se centra en el desarrollo de catalizadores de cobre(I) regulados supramolecularmente para su aplicación en reacciones de inserción de especies carbénicas metálicas a enlaces O–H, generando derivados α-alquilo/arilo-α-alcoxi/ariloxi. Se abordó el diseño, preparación, caracterización y aplicación de los catalizadores de cobre(I) derivados de ligandos bisoxazolina. Estos estudios demostraron que la actividad catalítica podía modularse con el uso de moléculas externas (agentes de regulación), que interaccionaban con la cadena polioxietilénica del ligando (centro de regulación) a través de interacciones supramoleculares de tipo ion-dipolo. La eficiencia de esta aproximación se demostró en reacciones de inserción de carbenos metálicos sobre alcoholes estructuralmente diversos (derivados cicloalquílicos, alquílicos y arílicos). Esta metodología se utilizó también para preparar intermedios sintéticos avanzados de compuestos con relevancia biológica. La segunda parte de esta tesis doctoral se centra en el uso de interacciones de tipo halógeno para formar el esqueleto de complejos metálicos. Se describe la síntesis de nuevos complejos supramoleculares de platino(II) y paladio(II) mediante el ensamblaje de dos bloques constituyentes que contienen fosfinas como grupos coordinantes, así como grupos capaces de formar enlaces de tipo halógeno. Se caracterizó en disolución y en estado sólido un conjunto de complejos estructuralmente diversos de platino(II) y paladio(II) derivados de difosfinas (supramoleculares). Se realizó un estudio de los intermedios de reacción que condujeron a los complejos de platino(II) finales. Se propone una racionalización mecanística para la formación de los complejos de platino(II) resultantes. El complejo XBPhos-Pt fue inactivo en reacciones de ciclación de eninos e hidrofenilación del etileno. Se presentan estrategias de activación del complejo XBPhos-Pt y análogos para nuevas transformaciones químicas.
This doctoral thesis encompasses the design and development of supramolecular catalysts derived from transition metal complexes and their application as catalysts in transformations of interest. The first part of the thesis focusses on the development of supramolecularly regulated copper(I) catalysts for the insertion of metal carbenes into O–H bonds leading to synthetically useful α-alkyl/aryl-α-alkoxy/aryloxy derivatives. The design, preparation, characterization and application of supramolecularly regulated copper(I) catalysts derived from bisoxazoline ligands is described. Our studies demonstrate that the catalytic performance of these systems can be modulated by the use of an external molecule (i.e. the regulation agent), which interacts with the polyethyleneoxy chain on the ligand (i.e. the regulation site) via supramolecular ion-dipole interactions. This approach has been applied to an array of structurally diverse alcohols (cycloalkyl, alkyl and aryl derivatives). Moreover, this methodology has been used to synthesize advanced synthetic intermediates of biologically relevant compounds. The second part of this thesis focusses on the use of halogen bonding interactions to construct the skeleton of metal complexes. The synthesis of new supramolecular platinum(II) and palladium(II) complexes by assembling two building blocks that incorporate phosphines as ligating groups, as well as complementary binding motifs for the assembly through halogen bonding, are reported. A set of structurally diverse platinum(II) and palladium(II) complexes derived from (halogen-bonded) diphosphines have been characterized in solution and in the solid state. A broad study of the reaction intermediates that led to the platinum(II) complexes has been performed. A tentative mechanistic rationalization for the formation of the platinum(II) complexes is proposed. The complex XBPhos-Pt has proved to be unreactive as a catalyst in cyclizations of enynes and in the hydrophenylation of ethylene. Strategies towards the activation of XBPhos-Pt and analogues for new chemical transformations are presented.
27
Fan, Yinan. "Rational synthesis of plasmonic/catalytic bimetallic nanocrystals for catalysis". Thesis, Sorbonne université, 2022. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2022SORUS189.pdf.
Testo completoAbstract (sommario):
Parmi les différents nanocatalyseurs, ceux constitués de nanoparticules de métaux nobles méritent une attention particulière en raison de leurs propriétés électroniques, chimiques et même optiques (dans le cas de transformations renforcées par les plasmons). Le platine ou le palladium sont bien connus pour leurs remarquables propriétés catalytiques, mais ils sont chers et leurs ressources sont limitées. En outre, les nanocatalyseurs monométallique ne peuvent conduire qu'à une gamme limitée de réactions chimiques. Ainsi, notre stratégie a été de développer des nanocatalyseurs bimétalliques composés de deux éléments métalliques qui peuvent présenter des effets synergiques entre leurs propriétés physicochimiques et une activité catalytique accrue. Nous avons ainsi conçu des nanocatalyseurs bimétalliques de type cœur-coquille composés d'un cœur en argent et d'une coquille en platine. L'intérêt est de combiner les activités catalytiques élevées et efficaces de la coquille de platine avec le cœur d'argent hautement énergétique, capable de renforcer les activités de la coquille grâce à ses propriétés plasmoniques. En outre, ces nanoparticules bimétalliques présentent souvent une activité catalytique supérieure en raison de la modification de la distance inter-atomique Pt-Pt (c'est-à-dire l'effet de contrainte). Dans ce travail de thèse, les nanoparticules Ag@Pt ont été synthétisées via un processus en deux étapes utilisant d'une part des nanoparticules d'Ag synthétisées chimiquement comme germes et d'autre part des complexes platine-oleylamine qui sont ensuite réduits à la surface des germes à une température contrôlée. Différentes tailles de germes d'Ag de 8 à 14 nm avec une très faible distribution de taille (<10%) ont été obtenues en ajustant le temps de réaction, la rampe de température, la concentration en précurseur d'Ag et la température finale pendant la synthèse. Différentes épaisseurs de coquille (de 1 à 6 couches atomiques) ont été obtenues en ajustant le rapport entre les concentrations de précurseur de platine et de germe d'argent. L'activité catalytique des nanoparticules Ag@Pt a été testée en considérant une réaction modèle de réduction du 4-nitrophénol en 4-aminophénol par NaBH4 en phase aqueuse. Nous avons observé que l'épaisseur de la coquille de Pt et la taille du noyau d'Ag influençaient les propriétés catalytiques et conduisaient à une activité catalytique accrue par rapport à l'argent ou au platine pur. Ceci a été attribué à des effets synergiques. De plus, nous avons observé une augmentation de l'activité catalytique des nanoparticules Ag et Ag@Pt sous irradiation lumineuse. Ce phénomène a été corrélé à la génération d'électrons chauds dans les noyaux d'Ag. Afin de développer une plateforme de nanocatalyse supportée, nous avons fabriqué des auto-assemblages 3D appelés aussi supercristaux composés de nanoparticules d'Ag@Pt obtenus spontanément après dépôt sur un substrat solide en raison de leur distribution de taille étroite et de leur forme homogène. L'activité catalytique de ces supercristaux pour la réaction d'évolution de l’hydrogène (HER) a été étudiée en suivant in situ par microscopie optique la production de nanobulles de gaz H2. Trois comportements distincts dans l'activité photo-catalytique (activité, activité intermittente et non-activité) ont été observés sur les supercristaux dans la même région d'intérêt. En outre, 50 % des assemblages ont été déterminés comme étant actifs pour l'HER qui a été démontrée comme étant accompagnée par une corrosion oxydative de l’argentAmong several nanocatalysts, those based on noble metal NPs deserve particular attention because of their electronic, chemical and even optical properties (in the case of plasmonic-enhanced transformations). Platinum or palladium are well known for their remarkable catalytic properties, but they are expensive and their resources are limited. In addition, single component nanocatalysts can only lead to a limited range of chemical reactions. Thus, our strategy was to develop bimetallic nanocatalysts composed of two metal elements that can exhibit synergistic effects between their physicochemical properties and enhanced catalytic activity. We have thus designed bimetallic nanocatalysts of the core-shell type composed of a silver core and a platinum shell. The interest is to combine the high and efficient catalytic activities of the platinum shell surface with the highly energetic silver core capable of enhancing the activities of the shell through its plasmonic properties. In addition, these bimetallic NPs often exhibit superior catalytic activity due to the modification of the Pt-Pt atomic bonding distance (i.e. the strain effect). In this thesis work, Ag@Pt NPs have been synthesized via a two-step process using chemically synthesized spherical Ag NPs as seeds on the one hand and platinum complexes with oleylamine on the other hand which are then reduced on the surface of the seeds at a controlled temperature. Different Ag seed sizes from 8 to 14 nm with a very low size distribution (<10%) have been obtained by adjusting the reaction time, temperature ramp, Ag precursor concentration and final temperature during the synthesis. The control of the shell thicknesses (from 1 to 6 atomic layers) has been possible by adjusting the ratio of platinum precursor to silver seed concentrations. The catalytic activity of the core-shell Ag@Pt NPs was tested by a model reaction of reduction of 4-nitrophenol to 4-aminophenol by NaBH4 in aqueous phase. We have observed that the thickness of the Pt shell and the size of the Ag core influence the catalytic properties and led increased catalytic activity compared to pure silver or platinum. This was attributed to synergistic effects. Furthermore, we have observed an enhancement of the catalytic activity of Ag and Ag@Pt NPs under light irradiation. This is correlated to the generation of hot electrons in the Ag core. Finally, in order to develop a supported nanocatalysis platform, 3D self-assemblies also called supercrystals composed of Ag@Pt nanoparticles have been spontaneously obtained after deposition on a solid substrate due to their narrow size distribution and homogeneous shape. The catalytic activity of these supercrystals for the hydrogen evolution reaction (HER) has been studied by following in situ by optical microscopy the production of H2 gas nanobubbles. Three distinct behaviors in photo-catalytic activity (activity, intermittent activity and non-activity) have been observed on the supercrystals in the same region of interest. In addition, 50% of the assemblies were determined to be active for HER which was shown to be accompanied by oxidative corrosion of silver
28
Meyer, Simon [Verfasser]. "Carbide Materials as Catalysts and Catalyst Supports for Applications in Water Electrolysis and in Heterogeneous Catalysis / Simon Meyer". München : Verlag Dr. Hut, 2014. http://d-nb.info/1058284967/34.
Testo completo
29
Ashraf, Muhammed Arfan. "Biomimetic ligands for transition metals". Thesis, King's College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391261.
Testo completo
30
Posada, Pérez Sergio. "Heterogeneous catalysis of green chemistry reactions on molybdenum carbide based catalysts". Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/552405.
Testo completoAbstract (sommario):
Our society has a problem with the use of fossil fuels, due to the vast and exceeding emissions derived from human activities. Two ways could be consider to mitigate these harmful effects. On the one hand, the capture, activation, and conversion of these hazardous gases towards valuable compounds, and on the other hand, the substitution of fossil fuels for renewable energies. This thesis encompasses the study of two different green chemistry reactions to convert the most abundant greenhouse gas in Earth's atmosphere and the production of a new environmental friendly fuel, the hydrogen.
In the current search for new catalysts, Transition Metal Carbides (TMCs) have arisen as an appealing alternative, because their exhibit broad and amazing physical and chemical properties and their low cost. In particular, titanium carbide (001) was proposed from experimental and theoretical points of view as active catalyst and support of small metal particles for CO2 hydrogenation to methanol and water gas shift reaction. However, given that titanium carbide is a cumbersome support to be used in applications due to the difficulty of obtaining nanoparticles on working conditions, we have carried out these reactions on cubic δ-MoC (001) and orthorhombic β-Mo2C (001) surfaces.
The adsorption and activation of a CO2 molecule on cubic δ-MoC (001) and orthorhombic β-Mo2C (001) surfaces have been investigated by means of periodic density functional theory based calculations using the Perdew-Burke-Ernzerhof exchange-correlation functional showing that both surface are promising catalyst for CO2 conversion because they are able to activate and bend the CO2 molecule. The β- Mo2C (001) surface is able to dissociate the CO2 molecule easily, with a low energy barrier, whereas δ-MoC (001) surface activates CO2 but it does not promote its direct dissociation. Experiments accomplished by the group of Dr. Jose Rodriguez revealed that CO and methane are the main products of the CO2 hydrogenation using β-Mo2C
(001) as catalyst, and the amount of methanol is lower. On the other hand, only CO and methanol are produced using δ-MoC (001).
Experiments revealed that the deposition of small copper particles on the carbide surfaces increase drastically the catalysts' activity and selectivity, which was demonstrated by theoretical calculations. On β-Mo2C, the amount of CO and methanol
increase whilst the amount of methane decrease, since copper blocks reactive sites on surface. This is a positive fact since copper avoid the excessive oxygen deposition, which deactivated the catalysts. On the other hand, the deposition of copper on δ-MoC
(001) increases a lot the amount of CO and methanol. In summary, our combining DFT- experimental study proposed the Cu/δ-MoC as promising catalyst for CO2 hydrogenation due to its activity (the amount of products is superior than other TMCS, metals, and the model of commercial catalysts), selectivity (only CO and methanol are produced), and stability ( this catalysts is not deactivated by the oxygen deposition).
The results obtained in the first part of the thesis were used to study the water gas shift reaction. Given that the excellent features, experiments proposed Au supported on δ-MoC (001) as catalysts. Our theoretical calculations demonstrated that clean δ-MoC (001) is not a good catalysts for WGS, due to the fact that the reverse reactions are favorable respect the direct ones, which implies that the amount of products is lower. Nevertheless, the deposition of Au clusters change the reaction mechanism, favoring the direct barriers instead of reverse ones, and increasing the amount of produced H2.
In summary, this thesis has displayed the prominent role of molybdenum carbides as support of small metal particles to catalyze green chemistry reactions.En aquesta tesi es mostra un treball computacional sobre l'ús de catalitzadors econòmics per a la conversió de CO2, un perillós gas d'efecte hivernacle i també per a la producció d'hidrogen, el combustible del futur. En la recerca actual de nous catalitzadors, els carburs de metalls de transició (TMC) han sorgit com una alternativa atractiva pel el seu baix cost i per exhibir excel·lents propietats físiques i químiques. En aquest treball utilitzarem com a catalitzadors les superfícies cúbica δ-MoC (001) i ortoròmbica β-Mo2C (001). L'adsorció de la molècula de CO2 mostra que ambdues superfícies són capaces d'activar i doblegar la molècula. La superfície β-Mo2C (001) és capaç de dissociar fàcilment la molècula de CO2, mentre que la superfície δ-MoC (001) activa CO2 però no la dissocia. Els experiments realitzats pel grup del Dr. Jose Rodriguez van revelar que el CO i el metà són els principals productes de la hidrogenació de CO2 utilitzant β-Mo2C (001) com a catalitzador, i la quantitat de metanol és menor. D'altra banda, només es produeixen CO i metanol utilitzant δ-MoC (001). La deposició de partícules de coure a les superfícies del carbur augmenta dràsticament l'activitat dels catalitzadors, cosa que es va demostrar mitjançant càlculs teòrics. A la superfície β-Mo2C, la quantitat de CO i metanol augmenten mentre que la quantitat de metà disminueix. D'altra banda, la deposició de coure a δ-MoC (001) augmenta molt la quantitat de CO i metanol. En resum, el nostre estudi proposa el Cu/δ-MoC com a prometedor catalitzador de la hidrogenació de CO2 a causa de la seva activitat (la quantitat de productes és superior a la resta de TMCS, metalls i el model de catalitzadors comercials), selectivitat (només el CO i el metanol es produeixen) i l'estabilitat (aquests catalitzadors no es desactiven per la deposició d'oxigen). Tenint en compte els resultats previs, es va proposar la deposició d'or en la superfície δ-MoC per a la producció d'hidrogen. Els càlculs teòrics demostren que la superfície δ-MoC (001) no és un bon catalitzador per WGS, però la deposició dels clústers d'or canvia el mecanisme de reacció i augmenta la quantitat d'H2 produïda.
31
Fjellander, Ester. "Self-adaptable catalysts : Importance of flexibility and applications in asymmetric catalysis". Doctoral thesis, KTH, Organisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12852.
Testo completoAbstract (sommario):
The topic of this thesis is the design and synthesis of biaryl-based self adaptableligands for asymmetric metal catalysis. The results discussed in papers I-III are covered, together with some unpublished results concerning substrate-adaptable catalysts. A general survey of self-adaptable catalysts is presented first. The second chapter of this thesis starts with a survey of inversion barriers in biphenyl-based ligands and catalysts. Thereafter, the determination of barriers to conformational adaptation in dibenzoazepines and dibenzophosphepines is described. Palladium complexes with a diphosphine ligand or a diamine ligand, as well as the free diamine ligand, were studied. Entropies and enthalpies of activation were determined with variable temperature NMR spectroscopy. The mechanism of conformational change in the metal complexes was elucidated. The third chapter describes the synthesis of semiflexible and rigid phosphinite ligands, as well as their application in rhodium-catalysed asymmetric hydrogenation. Modest enantioselectivities (up to 63% ee) were obtained. The semiflexible ligand was found to behave like the most active rigid diastereomer. The fourth chapter describes the behaviour of amine and phosphoramidite ligands in model complexes relevant to the palladium-catalysed asymmetricallylic alkylation of benchmark substrates. Diphosphoramidite and aminephosphoramiditeligands were designed and synthesised. Pd(olefin) complexesof diamine and diphosphoramidite ligands were studied, and their symmetry determined. It was found that both types of ligands are able to adapt their conformation to the substrate.QC20100630
32
Ou, Xiaoxia. "Developing hierarchically structured catalysts on cellular foams for continuous flow catalysis". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/developing-hierarchically-structured-catalysts-on-cellular-foams-for-continuous-flow-catalysis(e3fb780b-5212-4428-894d-288d4b819c6c).html.
Testo completoAbstract (sommario):
The development of modern chemical and environmental industry requires novel reactor concepts to enable the transfer of catalysts developed in laboratories into the industrial context. The applications of structured reactors/catalysts such as cellular foams are one of the most promising technologies that can facilitate this crucial step. Open-cell foams with stochastically interconnected cells and high porosities (>60%) can promote the low pressure drop during operation and improve the transport phenomena, overtaking the conventional fixed beds for continuous flow catalysis. In this PhD project, silicon carbide (SiC) cellular foams were investigated to evaluate the potential for developing heterogeneous catalysis using foam-based catalysts in continuous flow regime, due to the good compatibility with framework catalyst coatings and features of the cellular structure. The work was carried out by (i) studying morphological and structural features of SiC foams using X-ray computed tomography technique in relation to their implications for applications in chemical engineering; (ii) developing a microwave-assisted method based on the microwave absorbing feature of SiC for fast yet selective synthesis of zeolite (ZSM- 5) coatings on SiC foams; (iii) developing Fe-ZSM-5/SiC structured catalysts using a chemical vapour deposition method and subsequently studying their application as the foam bed reactor in the catalytic wet peroxide oxidation (CWPO) reaction (using phenol as the model compound); and (iv) developing intra-framework Fe-ZSM-5 catalyst on SiC foams (ferrisilicate/SiC) to address the Fe leaching issue from the Fe-ZSM-5/SiC catalyst. Satisfactory results were obtained through the systematic study of the SiC foam based catalysts, showing the potential of using SiC foams to develop structured catalysts for continuous flow environmental catalysis.
33
Durgun, Gülay Artok Levent. "Short-time suzuki reactions of arly halides catalyzed by palladium-loaded NaY zeolite under aerobic conditions/". [s.l.]: [s.n.], 2006. http://library.iyte.edu.tr/tezler/master/kimya/T000528.pdf.
Testo completoAbstract (sommario):
Thesis (Master)--İzmir Institute of Technology, İzmir, 2006.Keywords:Suzuki reactions, palladium, NaYzeolite, heterogeneous catalyst, C-C coupling. Includes bibliographical references (leaves. 71-81).
34
Lev, Daniel Abraham. "Group 8 and 9 half sandwich complexes of N-heterocyclic phosphines : synthesis, reactivity, and catalysis /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3158465.
Testo completo
35
Paliga, James Francis. "Developing Earth-abundant metal-catalysts for hydrofunctionalisation". Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31115.
Testo completoAbstract (sommario):
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.
36
Peneau, Virginie. "Activation of hydrocarbons and their catalytic oxidation by heterogeneous catalysis". Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/74614/.
Testo completoAbstract (sommario):
The targets of this thesis were the selective oxidation of hydrocarbons under mild conditions, using cheap and environmentally friendly oxidants and initiators. Three projects are treated; the oxidation of an alkane using O2 and a co-oxidant, the oxidation of toluene using TBHP (tert-butyl hydroperoxide) and finally the oxidation of propane using hydrogen peroxide. C-H bond activation, O2 activation and high conversion with high selectivity were essential points to investigate. In the first project, alkane oxidation was studied in presence of a co-oxidant. The co-oxidant has for purpose to initiate the activation of the alkane and O2, as well as prevent the over-oxidation of the alkane. The co-oxidation of octane using benzaldehyde has been investigated using 1 wt. % AuPd/ C catalyst; the hypothesis is that benzaldehyde oxidation would use a radical mechanism able to activate octane to octanol. Also, the coupling of octanol with activated benzaldehyde would prevent the over-oxidation of octanol by the formation of an ester; octylbenzoate. The aim of the second study was to investigate the selective oxidation of toluene using TBHP at 80 °C with supported noble metal nanoparticle catalysts prepared by sol-immobilisation techniques. Au, Pd and Pt have been use to form mono, bi and trimetallic catalysts of different morphology supported on C and TiO2. These catalysts have been tested for toluene oxidation. The catalyst showing the best activity has been used for further investigation such as reuse test, using H2O2 as oxidant or O2 activation. The third project target was to oxidise propane using H2O2 in mild conditions. 2.5 wt. % Fe/ ZSM-5 (30) has been used to investigate reaction conditions in order to optimise the system. This catalyst has been acid treated; standard and treated catalysts were characterised and analysed to identify the structure and active sites. Role of supports and metals (mono and bimetallic) has been explored in order to improve this system.
37
Barnett, A. E. "Automotive catalysis". Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419491.
Testo completo
38
Giacinto, Pietro <1980>. "Computational Investigation of Catalyzed Organic Reactions: Metal- and Organo-Catalysis, Bio-Catalysis and Carbo-Catalysis". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7558/1/Pietro_Giacinto_PhD_Thesis.pdf.
Testo completoAbstract (sommario):
In this thesis the results of a Computational Organic Chemistry Ph.D. work course ranging from organometallic to metal-free and enzymatic catalysis is discussed. Various energetic and mechanistic aspects of organic reactions in catalysis are the key-issues which are addressed. A multidisciplinary approach allowed the development of several research projects in collaboration with experimental groups and combined experimental-theoretical works were carried out. Notes and comments concerning the theoretical models used and the experimental work carried out by the research groups who cooperated with us, are reported.
The thesis comprises four main sections. The first section provides basic information on the computational methods used in the present work. In the subsequent sections (Part II, Part III and Part IV) we focus on different aspects of organic catalysis.
In Part II the results of computational studies on the mechanism of various metal-catalyzed reactions are presented. In particular we describe organic reactions catalyzed by Gold(I) complexes. We consider some synthetically important processes in organic chemistry. The purpose of these studies was to discover some general rules to rationalize the role of gold complexes in different classes of organic reactions. Furthermore, at the end of this section we describe a mechanistic investigation of an example of organo-catalysis, thus not involving metal complexes.
In Part III we focus on an emerging and promising area of "metal-free" catalysis, based on carbon nanostructures such as graphite, graphene, graphene oxide, fullerenes and carbon nanotubes (CNTs). This “metal-free” catalysis is usually denoted as Carbocatalysis. The energy contributions that may influence the course of a reaction inside a CNT, have been elucidated by means of computational methods.
In Part IV the computational approach is used to elucidate the mechanism of an enzymatic reaction. We describe the results obtained in the study of tyrosine O-sulfonation catalyzed by human Tyrosylprotein Sulfotransferases-2.
39
Giacinto, Pietro <1980>. "Computational Investigation of Catalyzed Organic Reactions: Metal- and Organo-Catalysis, Bio-Catalysis and Carbo-Catalysis". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7558/.
Testo completoAbstract (sommario):
In this thesis the results of a Computational Organic Chemistry Ph.D. work course ranging from organometallic to metal-free and enzymatic catalysis is discussed. Various energetic and mechanistic aspects of organic reactions in catalysis are the key-issues which are addressed. A multidisciplinary approach allowed the development of several research projects in collaboration with experimental groups and combined experimental-theoretical works were carried out. Notes and comments concerning the theoretical models used and the experimental work carried out by the research groups who cooperated with us, are reported.
The thesis comprises four main sections. The first section provides basic information on the computational methods used in the present work. In the subsequent sections (Part II, Part III and Part IV) we focus on different aspects of organic catalysis.
In Part II the results of computational studies on the mechanism of various metal-catalyzed reactions are presented. In particular we describe organic reactions catalyzed by Gold(I) complexes. We consider some synthetically important processes in organic chemistry. The purpose of these studies was to discover some general rules to rationalize the role of gold complexes in different classes of organic reactions. Furthermore, at the end of this section we describe a mechanistic investigation of an example of organo-catalysis, thus not involving metal complexes.
In Part III we focus on an emerging and promising area of "metal-free" catalysis, based on carbon nanostructures such as graphite, graphene, graphene oxide, fullerenes and carbon nanotubes (CNTs). This “metal-free” catalysis is usually denoted as Carbocatalysis. The energy contributions that may influence the course of a reaction inside a CNT, have been elucidated by means of computational methods.
In Part IV the computational approach is used to elucidate the mechanism of an enzymatic reaction. We describe the results obtained in the study of tyrosine O-sulfonation catalyzed by human Tyrosylprotein Sulfotransferases-2.
40
Yang, Fangfang. "Targeted supported laccase based hybrid catalyst for continuous flow catalysis". Electronic Thesis or Diss., Ecole centrale de Marseille, 2021. http://www.theses.fr/2021ECDM0009.
Testo completoAbstract (sommario):
Les catalyseurs hétérogènes sont aujourd’hui'hui largement développés afin d'obtenir une meilleure stabilité, une meilleure réutilisation ainsi qu'une meilleure localisation. Dans cette optique, nous avons d'abord préparé des catalyseurs hétérogènes à base d'enzymes par l'immobilisation d’une laccase d'origine fongique contenant seulement deux lysines de surface spatialement proches (K40, K71) ainsi que deux de ses variants contenant une lysine unique -une située à proximité du site d'oxydation du substrat (K157) et une à l'opposé de ce site d'oxydation (K71)- dans des mousses de silice de type Si(HIPE) à porosités contrôlées. L'immobilisation a été réalisée par liaison covalente entre l'enzyme et la mousse activée à faible teneur en glutaraldéhyde. En testant la décoloration de colorants dans un réacteur à flux continu, nous montrons que l'activité du catalyseur hétérogène est comparable à son homologue homogène. Son activité opérationnelle reste aussi élevée que 60 % après douze cycles de décoloration consécutifs et un an de stockage. Plus important encore, en comparant les activités sur différents substrats pour des catalyseurs orientés différemment, nous montrons une discrimination double pour l'ABTS par rapport à l'ascorbate. Par ailleurs, les métalloenzymes artificielles peuvent utiliser les avantages des catalyseurs métalliques et enzymatiques pour réaliser une oxydation aérobie de manière durable. Nous avons donc immobilisé un complexe Pd(II) à base de biquinoline et une laccase dans des monolithes de silice pour l'oxydation de l'alcool veratrylique. Afin de contrôler la réactivité, trois méthodes d'immobilisation ont été utilisées pour la construction de ces catalyseurs hybrides hétérogènes. Les catalyseurs hybrides immobilisés présentent une activité améliorée par rapport au complexe de Pd immobilisé seul pour chaque méthode testée, attestant de la synergie entre le Pd et la laccase. En modulant l'orientation de l'enzyme vers le complexe de Pd(II) et la mousse de silice, nous montrons que l'activité de l'hybride de Pd(II)/UNIK157 est en moyenne deux fois plus importante que celle de Pd(II)/UNIK71. Une bonne stabilité et réutilisation est observée quel que soit l'orientation de l'enzyme. Cette étude donne un aperçu de l'utilisation de supports solides qui au-delà de permettre la stabilité et la réutilisation deviennent des partenaires synergiques dans le processus catalytiqueHeterogeneous catalysts are now widely developed to obtain improved stability, reusability, and localization. In this view, we first prepared the enzyme-based heterogeneous catalysts by the immobilization of a fungal laccase containing only two spatially close surface lysines (K40, K71) and its variants containing a unique lysine -one located in the vicinity of the substrate oxidation site (K157) and one at the opposite side of this oxidation site (K71)- into Si(HIPE) type silica foams bearing controlled porosities. Immobilization was achieved by a covalent bond forming reaction between the enzyme and the low glutaraldehyde activated foam. Testing dye decolorization in a continuous flow reactor, we show that the activity of the heterogeneous catalyst is comparable to its homogeneous counterpart. Its operational activity remains as high as 60 % after twelve consecutive decolorization cycles and one-year storage. More importantly, comparing activities on different substrates for differentially oriented catalysts, we show a two-fold discrimination for ABTS relative to ascorbate. In addition, artificial metalloenzymes can use the advantages of both metallic and enzymatic catalysts to perform aerobic oxidation in a sustainable fashion. We thus co-immobilized a biquinoline-based-Pd(II) complex and laccase into silica monoliths for veratryl alcohol oxidation. To address the control of reactivity, three methods of immobilization were used for the construction of the heterogeneous hybrid catalysts. The immobilized hybrid catalysts show an improved activity compared to the immobilized Pd complex alone for each tested method, attesting for the synergy between Pd and laccase. By tuning enzyme orientation towards Pd(II) complex and silica foam, we show that the activity of the Pd(II)/UNIK157 hybrid exhibits an averaged two-fold increase compared to Pd(II)/UNIK71. A good stability and reusability is observed for both enzyme orientations. This study provides insights into the use of solid supports that beyond allowing stability and reusability becomes synergistic partners in the catalytic process
41
Barakat, Khaldoon A. "Computational Studies of Selected Ruthenium Catalysis Reactions". Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc5203/.
Testo completoAbstract (sommario):
Computational techniques were employed to investigate pathways that would improve the properties and characteristics of transition metal (i.e., ruthenium) catalysts, and to explore their mechanisms. The studied catalytic pathways are particularly relevant to catalytic hydroarylation of olefins. These processes involved the +2 to +3 oxidation of ruthenium and its effect on ruthenium-carbon bond strengths, carbon-hydrogen bond activation by 1,2-addition/reductive elimination pathways appropriate to catalytic hydrogen/deuterium exchange, and the possible intermediacy of highly coordinatively unsaturated (e.g., 14-electron) ruthenium complexes in catalysis. The calculations indicate a significant decrease in the Ru-CH3 homolytic bond dissociation enthalpy for the oxidation of TpRu(CO)(NCMe)(Me) to its RuIII cation through both reactant destabilization and product stabilization. This oxidation can thus lead to the olefin polymerization observed by Gunnoe and coworkers, since weak RuIII-C bonds would afford quick access to alkyl radical species. Calculations support the experimental proposal of a mechanism for catalytic hydrogen/deuterium exchange by a RuII-OH catalyst. Furthermore, calculational investigations reveal a probable pathway for the activation of C-H bonds that involves phosphine loss, 1,2-addition to the Ru-OH bond and then reversal of these steps with deuterium to incorporate it into the substrate. The presented results offer the indication for the net addition of aromatic C-H bonds across a RuII-OH bond in a process that although thermodynamically unfavorable is kinetically accessible. Calculations support experimental proposals as to the possibility of binding of weakly coordinating ligands such as dinitrogen, methylene chloride and fluorobenzene to the "14-electron" complex [(PCP)Ru(CO)]+ in preference to the formation of agostic Ru-H-C interactions. Reactions of [(PCP)Ru(CO)(1-ClCH2Cl)][BAr'4] with N2CHPh or phenylacetylene yielded conversions that are exothermic to both terminal carbenes and vinylidenes, respectively, and then bridging isomers of these by C-C bond formation resulting from insertion into the Ru-Cipso bond of the phenyl ring of PCP. The QM/MM and DFT calculations on full complexes [(PCP)(CO)Ru=(C)0,1=CHPh]+ and on small models [(PCP')(CO)Ru=(C)0,1=CH2]+, respectively, offered data supportive of the thermodynamic feasibility of the suggested experimental mechanisms and their proposed intermediates.
42
Trant, Aoife Geraldine. "Structural and catalytic studies of novel Au/Ni enantioselective catalysts". Thesis, St Andrews, 2008. http://hdl.handle.net/10023/854.
Testo completo
43
Chen, Gang. "Synthesis of fluorinated BINOL ligands and asymmetric catalysis with its derived catalysts". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58758.pdf.
Testo completo
44
Yamamoto, Takashi. "Studies on the Catalysis by New Solid Acid Catalysts and the Characterization". Kyoto University, 1999. http://hdl.handle.net/2433/77922.
Testo completo
45
Arthur, Richard John. "Catalytic dechlorination of chloroalkenes by multimetallic cobaloximes : synthesis, chemistry and catalysis". Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/55003/.
Testo completoAbstract (sommario):
The work presented in this thesis is primarily concerned with the synthesis and applications of cobaloximes towards reductive dechlorination of organohalides, such as perchlorocthylene. The toxicity and relevance of these organohalides is discussed in chapter one, which also describes the current industrial methods for their removal from the environment. An insight into the mechanism of dechlorination of perchloroethylene has been offered in chapter three, which describes the mechanism of dechlorination of PCE. This reaction proceeds via electron transfer from the catalytic cobaloxime to the PCE for the removal of the first chloride, but the subsequent dechlorination steps proceed via organocobalt intermediates. The role of the axial ligands and the coordination chemistry' of the cobaloxime intermediate during reduction from Co(III) to Co(I) is then studied by means of a cross over experiment. Chapters four and five describe more complex, novel multimetallic cobaloximes, which have been designed and synthesised for their use as dechlorination catalysts. The structure and electrochemical behaviour of these multimetallic cobaloximes has been discussed and their catalytic ability towards dechlorination of PCE has been studied. The work in chapter four looks at cobaloximes with a u2-dicobaltcarbonyl bridged ligand, whilst chapter five describes a series of nitrogen heterocycle bridged dinuclear cobaloximes. As a result of the findings of chapter three, the final section of chapter five investigates the incorporation of the secondary metal centre into an equatorial ligand.
46
Rajurkar, K. B. "Studies in catalysis and reaction engineering aspects of multiphase catalytic reactions". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2008. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2704.
Testo completo
47
Harms, Stefan Mathias. "The oligomerisation of propene over nickel oxide silica alumina". Master's thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/22157.
Testo completoAbstract (sommario):
Bibliography: pages 129-132.A synthesis techniQue was developed for the preparation of a nickel oxide sil ica alumina catalyst. The propene oligomerisation activity and the selectivity of the catalysts prepared by homogeneous decomposition deposition (HDD) were investigated and compared with nickel oxide silica alumina catalysts prepared by the techniQues of impregnation (IMP) and co-precipitation (SG). Amongst others. the effect of the nickel content. reacti6n temperature and pressure, and water content of the feed, on the activity and selectivity. were investigated. Also investigated were the lifetime of the various catalysts and, in the case of HDD type catalysts. the ability to oligomerise high molecular weight hydrocarbons (Cb). Nickel oxide silica alumina prepared by the HDD method is more active for the propene oligomerisation than catalysts prepared by the IMP and SG methods. The product spectrum in the case of IMP and HDD type catalysts are similar, with a propene dimer (Cb) being the main product. In the case of SG type catalysts. however. a shift to heavier products was observed, i.e., propene dimer (Cb) and trimer (Cq) were formed in eQual Quantities. It is proposed that the increase in activity of HDD type catalysts was due to a large extent of metal dispersion and distribution and a stronger interaction between the metal and the support. It is also proposed that the metal is readily accessible to the reactant molecules. The activity and selectivity of catalysts prepared by the HDD method were independent of the nickel content. This was not the case for IMP and SG type catalysts. both of which showed decreasing activity with increasing nickel content when the nickel content was increased beyond 5 wt%. The lifetimes of the various catalysts were also examined. From the results obtained. over the first 10 h. the lifetime of HOD type catalysts was superior to that of the other catalysts studied. The activity and selectivity of the various catalysts were sensitive to the reaction conditions. Thus moving into the vapour phase. by either increasing the temperature at a fixed pressure or decreasing the pressure at a fixed temperature. was in each case acCompanied by a shift to heavier products and a decrease in activity.
48
Werner, Emilie. "Catalysis at the origin of life and catalysis today, a 3.8-billion-year jump". Electronic Thesis or Diss., Strasbourg, 2024. https://publication-theses.unistra.fr/public/theses_doctorat/2024/Werner_Emilie_2024_ED222.pdf.
Testo completoAbstract (sommario):
La catalyse, permettant une réactivité sélective et accrue, est exploitée aussi bien en chimie de synthèse qu’en biologie. Cette thèse l’abordera à deux temporalités différentes. Dans un premier temps, les processus chimiques aux origines de la vie seront étudiés au travers de deux types de catalyse non enzymatique : la catalyse par les métaux rares et la cocatalyse métal/coenzyme. Cette dernière serait un produit de l’évolution pour s’affranchir d’environnements rares et permettre à la chimie prébiotique de se propager vers des milieux communs. Dans un deuxième temps, la catalyse métallique moderne sera discutée. Une nouvelle variante azotée du réarrangement de Piancatelli sera décrite avec des nucléophiles sulfoximines, permettant d’accéder directement et avec de bons rendements à des 4-sulfoximinocyclopenténones inédites, structures prometteuses pour des applications en chimie médicinaleCatalysis enables selective and enhanced reactivity and is harnessed in both synthetic chemistry and biology. This thesis will discuss this concept at two different time points. Firstly, the chemical processes at the origins of life will be studied through two types of non-enzymatic catalysis: rare metal catalysis and metal/coenzyme cocatalysis. The latter is thought to be a product of evolution to become independent from rare environments and enable prebiotic chemistry to spread to more common media. Secondly, modern metal catalysis will be examined. A new aza-variant of the Piancatelli rearrangement will be described with sulfoximine nucleophiles, giving direct access to unprecedented 4-sulfoximinocyclopentenone scaffolds in good yields. These structures hold promises for applications in drug discovery
49
Large, Benjamin. "Activation sélective de naphtalènes et synthèse d'architectures polycycliques étendues". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLV070/document.
Testo completoAbstract (sommario):
Comme le naphtalène a récemment émergé comme un socle fondamental en chimie médicinale, le développement de méthodologies menant à des plateformes fonctionnalisées basées sur du naphtalène est devenu un centre d’intérêt majeur de la communauté scientifique. En effet, des conditions expérimentales optimisées sur le benzène ou d’autre noyaux aromatiques ne peuvent pas toujours être transposées au naphtalène. Ces dernières peuvent parfois conduire à des résultats différents, possiblement dû à l’aromaticité plus faible de ce bicycle aromatique.Dans ce contexte, cette thèse s’articule autour du naphtalène et de ses dérivés. Des méthodes variées permettant une fonctionnalisation sélective de différentes positions de cette plateforme, ainsi que des stratégies de synthèses d’architectures polycycliques ont été développées.Notre attention s’est ensuite portée sur des précurseurs du naphtalène, en particulier sur les tetralones. En utilisant une méthode basée sur l’utilisation d’un groupe directeur éphémère, la position 8 de ce bicycle a été arylée, et les différents composés ainsi obtenus ont pu être convertis en d’autre plateformes polycycliques. En complément, des calculs DFT ont permis d’expliquer la régiosélectivité observée lors de la synthèse de fluorenones étendues, et d’étudier le mécanisme d’arylation dirigée des tetralonesBecause naphthalene has recently emerged as a fundamental platform in medicinal chemistry, the development of methodologies leading to diversely functionalised naphthalene-based platforms has become a prime concern of the scientific community. Indeed, experimental conditions previously optimised for benzene and other aromatic rings cannot always be applied to naphthalene. These methods can sometimes lead to different results, as a consequence of the lower aromaticity of the naphthalene core.In this context, this thesis is dedicated to the naphthalene and its derivatives. Various methods to selectively functionalise the different positions of the naphthalene core and synthetic pathways to extended polycyclic architectures were developed.Next, we focused on naphthalene precursors, especially on tetralones. Using a strategy involving a transient directing group, the position 8 of these bicycles was successfully arylated and the resulting compounds were successfully converted into other polycyclic platforms. In addition, DFT calculation have been used to explain the regioselectivity observed during the synthesis of extended fluorenones, and to study the mechanism of directed arylation of tetralones
50
Sengupta, Sujata. "1,2,3-(NH)-triazoles its metal-free synthesis and application as ligands in transition metal catalysis /". Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/10984.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--West Virginia University, 2010.Title from document title page. Document formatted into pages; contains xii, 328 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 81-91).