Littérature scientifique sur le sujet « Micellar catalysi »
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Articles de revues sur le sujet "Micellar catalysi"
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Cibulka, Radek, Lenka Baxová, Hana Dvořáková, František Hampl, Petra Ménová, Viktor Mojr, Baptiste Plancq et Serkan Sayin. « Catalytic effect of alloxazinium and isoalloxazinium salts on oxidation of sulfides with hydrogen peroxide in micellar media ». Collection of Czechoslovak Chemical Communications 74, no 6 (2009) : 973–93. http://dx.doi.org/10.1135/cccc2009030.
Texte intégralRésumé :
Three novel amphiphilic alloxazinium salts were prepared: 3-dodecyl-5-ethyl-7,8,10-trimethylisoalloxazinium perchlorate (1c), 1-dodecyl-5-ethyl-3-methylalloxazinium perchlorate (2b), and 3-dodecyl-5-ethyl-1-methylalloxazinium perchlorate (2c). Their catalytic activity in thioanisole (3) oxidation with hydrogen peroxide was investigated in micelles of sodium dodecylsulfate (SDS), hexadecyltrimethylammonium nitrate (CTANO3) and Brij 35. Reaction rates were strongly dependent on the catalyst structure, on the type of micelles, and on pH value. Alloxazinium salts 2 were more effective catalysts than isoalloxazinium salts 1. Due to the contribution of micellar catalysis, the vcat/v0 ratio of the catalyzed and non-catalyzed reaction rates was almost 80 with salt 2b solubilized in CTANO3 micelles. Nevertheless, the highest acceleration was observed with non-amphiphilic 5-ethyl-1,3-dimethylalloxazinium perchlorate (2a) in CTANO3 micelles (vcat/v0 = 134). In this case, salt 2a presumably acts as a phase-transfer catalyst bringing hydrogen peroxide from the aqueous phase into the micelle interior. Synthetic applicability of the investigated catalytic systems was verified on semi-preparative scale.
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Khan, Mohammad Niyaz, et Ibrahim Isah Fagge. « Kinetics and Mechanism of Cationic Micelle/Flexible Nanoparticle Catalysis : A Review ». Progress in Reaction Kinetics and Mechanism 43, no 1 (mars 2018) : 1–20. http://dx.doi.org/10.3184/146867818x15066862094905.
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The aqueous surfactant (Surf) solution at [Surf] > cmc (critical micelle concentration) contains flexible micelles/nanoparticles. These particles form a pseudophase of different shapes and sizes where the medium polarity decreases as the distance increases from the exterior region of the interface of the Surf/H2O particle towards its furthest interior region. Flexible nanoparticles (FNs) catalyse a variety of chemical and biochemical reactions. FN catalysis involves both positive catalysis ( i.e. rate increase) and negative catalysis ( i.e. rate decrease). This article describes the mechanistic details of these catalyses at the molecular level, which reveals the molecular origin of these catalyses. Effects of inert counterionic salts (MX) on the rates of bimolecular reactions (with one of the reactants as reactive counterion) in the presence of ionic FNs/micelles may result in either positive or negative catalysis. The kinetics of cationic FN (Surf/MX/H2O)-catalysed bimolecular reactions (with nonionic and anionic reactants) provide kinetic parameters which can be used to determine an ion exchange constant or the ratio of the binding constants of counterions.
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Broxton, Trevor J. « Micellar Catalysis of Organic Reactions. XXXVIII A Study of the Catalytic Effect of Micelles of 3-Hydroxymethyl-1-tetradecylpyridinium Bromide on Amide Hydrolysis and Nucleophilic Aromatic Substitution ». Australian Journal of Chemistry 51, no 7 (1998) : 541. http://dx.doi.org/10.1071/c98053.
Texte intégralRésumé :
The preparation of 3-hydroxymethyl-1-tetradecylpyridinium bromide and its use as a catalyst of nucleophilic aromatic substitution and also amide hydrolysis are reported. It was found that the hydroxydehalogenation of nitro-activated aryl halides was much faster in these micelles than in the presence of cetyl(2-hydroxyethyl)dimethylammonium bromide. It was concluded that the increased catalysis of nucleophilic aromatic substitution by this micelle was due to a faster decomposition of the aryl micellar ether which must occur before the phenolate product is released. No such difference in the two micelles was found for amide or thioamide hydrolysis since in these reactions the product amine is produced in the first step of the reaction and decomposition of the acylated micelle is not required in the rate-determining step of the reaction.
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Drennan, Catherine E., Rachelle J. Hughes, Vincent C. Reinsborough et Oladega O. Soriyan. « Article ». Canadian Journal of Chemistry 76, no 2 (1 février 1998) : 152–57. http://dx.doi.org/10.1139/v97-226.
Texte intégralRésumé :
Kinetic studies through stopped-flow spectroscopy were undertaken in the dilute solution range of anionic surfactants where pronounced rate enhancement or inhibition of Ni2+-ligand complexations is often observed at surfactant concentrations much below the critical micelle concentration (CMC). The results are interpreted in terms of Ni-surfactant micelles as the agents responsible for the rate changes in dilute surfactant solution. At higher surfactant concentrations these micelles are transformed into mixed micelles (counterion and size changes), eventually becoming normal surfactant micelles close to the CMC. Surface tension, dye solubility, conductivity, and fluorescent probe investigations support this interpretation.Key words: micellar catalysis, sodium dodecyl sulfate, micelles, critical micelle concentration, premicelles, Ni2+-ligand complexations.
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Broxton, TJ, JR Christie et RPT Chung. « Micellar Catalysis of Organic Reactions. XXVI. SNAr Reactions of Azide Ions ». Australian Journal of Chemistry 42, no 6 (1989) : 855. http://dx.doi.org/10.1071/ch9890855.
Texte intégralRésumé :
The azidodehalogenation of a number of aromatic compounds has been studied in the presence of micelles of cetyltrimethylammonium bromide (ctab). The variation of the observed rate of reaction with ctab concentration has been treated by using the model of Rodenas and Vera to determine the rate constant for reaction in the micellar pseudo-phase, k2m, the binding constant of the substrate to the micelle, Ks, and the nucleophile-micellar counter ion exchange constant KAzBr :. The ratio of the rate constants in the micellar pseudo-phase and in water varied between 0.9 and 52. For reactions involving the production of a dianionic intermediate the largest catalysis was found for compounds containing two nitro groups to stabilize the double negative charge. In addition significant differences in the catalysis were found between compounds having the reaction centre at the micelle-water interface and those for which the reaction centre was more buried inside the micelle. As previously reported the resulting aryl azides undergo cyclization to form a benzofuroxan if a nitro group is located ortho to the azide group. Furthermore, a reversible photochemical reaction was detected for two compounds having a carboxylate group ortho to the azide group.
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Steven, Alan. « Micelle-Mediated Chemistry in Water for the Synthesis of Drug Candidates ». Synthesis 51, no 13 (21 mai 2019) : 2632–47. http://dx.doi.org/10.1055/s-0037-1610714.
Texte intégralRésumé :
Micellar reaction conditions, in a predominantly aqueous medium, have been developed for transformations commonly used by synthetic chemists working in the pharmaceutical industry to discover and develop drug candidates. The reactions covered in this review are the Suzuki–Miyaura, Miyaura borylation, Sonogashira coupling, transition-metal-catalysed CAr–N coupling, SNAr, amidation, and nitro reduction. Pharmaceutically relevant examples of these applications will be used to show how micellar conditions can offer advantages in yield, operational ease, amount of waste generated, transition-metal catalyst loading, and safety over the use of organic solvents, irrespective of the setting in which they are used.1 Introduction2 Micelles as Solubilising Agents3 Micelles as Nanoreactors4 Designer Surfactants5 A Critical Evaluation of the Case for Chemistry in Micelles6 Scope of Review7 Suzuki–Miyaura Coupling8 Miyaura Borylation9 Sonogashira Coupling10 Transition-Metal-Catalysed CAr–N Couplings11 SNAr12 Amidation13 Nitro Reduction14 Micellar Sequences15 Summary and Outlook
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Dahadha, Adnan A., Mohammed Hassan, Tamara Mfarej, Razan Bani Issa, Mohamed J. Saadh, Mohammad Al-Dhoun, Mohammad Abunuwar et Nesrin T. Talat. « The Catalytic Influence of Polymers and Surfactants on the Rate Constants of Reaction of Maltose with Cerium (IV) in Acidic Aqueous Medium ». Journal of Chemistry 2022 (1 juillet 2022) : 1–11. http://dx.doi.org/10.1155/2022/2609478.
Texte intégralRésumé :
Kinetics of the reaction of maltose with cerium ammonium sulfate were analyzed spectrophotometrically by observing the decrease of the absorbance of cerium (IV) at 385 nm in the presence and absence of polyethylene glycols (600, 1500, and 4000) and polyvinylpyrrolidone (PVP), in addition to anionic micelles of sodium dodecyl sulfate (SDS), cationic micelles of cetyltrimethylammonium bromide (CTAB) and non-ionic micelles of Tween 20 surfactants. Generally, there is little literature about using the polymers (PEGs and PVP) as catalysts in the oxidation-reduction reactions. Therefore, the major target of this work was to investigate the influence of the nature of polymers and surfactants on the oxidation rates of maltose by cerium (IV) in acidic aqueous media, as well as employing the Piszkiewicz model to explain the catalytic effect. The kinetic runs were derived by adaptation of the pseudo first-order reaction conditions with respect to the cerium (IV). The reaction was found to be first-order with respect to the oxidant and fractional-order to maltose and H2SO4. The reaction rates were enhanced in the presence of polymer and micellar catalysis. Indeed, the surfactants were found to work perfectly close to their critical micelle concentrations (CMC). Electrostatic interaction and H-bonding appear to play an influential role in binding maltose molecules to polymer/surfactant micelles, while oxidant ions remain at the periphery of the Stern layer within the micelle.
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Oranli, Levent, Pratap Bahadur et Gérard Riess. « Hydrodynamic studies on micellar solutions of styrene–butadiene block copolymers in selective solvents ». Canadian Journal of Chemistry 63, no 10 (1 octobre 1985) : 2691–96. http://dx.doi.org/10.1139/v85-447.
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Hydrodynamic radius of micelles of several block copolymers in different selective solvents (for both types of blocks) was determined from photon correlation spectroscopy. The boundaries of micellar solutions in heptane (good solvent for polybutadiene block) and dimethylformamide (good solvent for polystyrene block) were established for polymers in terms of their molecular mass and block composition. The photon correlation spectroscopy data in combination with intrinsic viscosities of block copolymers in selective solvents were used to determine micellar molecular mass and aggregation number. The influence of temperature on the micelle size was examined. The block copolymer micelles could solubilize a certain amount of insoluble homopolymer within their insoluble core. 1H nmr spectra were examined to study the influence of temperature on micellar systems.
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Wasylishen, Roderick E., Jan C. T. Kwak, Zhisheng Gao, Elisabeth Verpoorte, J. Bruce MacDonald et Ross M. Dickson. « NMR studies of hydrocarbons solubilized in aqueous micellar solutions ». Canadian Journal of Chemistry 69, no 5 (1 mai 1991) : 822–33. http://dx.doi.org/10.1139/v91-122.
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Information concerning the solubilization of hydrocarbons in ionic surfactant micelles was obtained from 2H NMR relaxation, 1H NMR chemical shifts, and 1H NMR paramagnetic relaxation measurements. The rotational motion of deuterated hydrocarbons, which is related to the micellar microviscosity at the location of the hydrocarbons, was probed by 2H NMR relaxation. The relaxation data are interpreted using both the two-step and the single-step models, and the results are discussed in terms of the micellar microviscosity and the location of the hydrocarbons in micelles. The location of the hydrocarbons in micelles was further investigated by determining the aromatic ring current-induced 1H chemical shifts along the surfactant alkyl chain and by comparing the 1H spin-lattice relaxation enhancement of the hydrocarbons and the surfactant alkyl chain, induced by Mn2+ on the micellar surface. The hydrocarbons used include benzene, naphthalene, acenaphthalene, triphenylene, cyclohexane, cyclododecane, and tert-butylcyclohexane and the surfactants studied are hexadecyl-, tetradecyl-, and dodecyltrimethylammonium bromide; hexadecyl-, tetradecyl-, and dodecylpyridinium halide; and sodium dodecyl sulfate. The results indicate that the micellar microviscosity at the location of saturated hydrocarbons is approximately 5 cP for both the cationic and anionic micelles, whereas the micellar microviscosity at the location of unsaturated hydrocarbons is much higher. The unsaturated hydrocarbons are found to reside primarily near the surfactant headgroup in the cationic micelles, but are distributed evenly throughout the anionic SDS micelles. The saturated hydrocarbons appear to be located in the interior of the micelles. Key words: NMR, relaxation, solubilization, surfactant, micelle.
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Gebicka, Lidia, et Monika Jurgas-Grudzinska. « Activity and Stability of Catalase in Nonionic Micellar and Reverse Micellar Systems ». Zeitschrift für Naturforschung C 59, no 11-12 (1 décembre 2004) : 887–91. http://dx.doi.org/10.1515/znc-2004-11-1220.
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Catalase activity and stability in the presence of simple micelles of Brij 35 and entrapped in reverse micelles of Brij 30 have been studied. The enzyme retains full activity in aqueous micellar solution of Brij 35. Catalase exhibits “superactivity” in reverse micelles composed of 0.1 ᴍ Brij 30 in dodecane, n-heptane or isooctane, and significantly lowers the activity in decaline. The incorporation of catalase into Brij 30 reverse micelles enhances its stability at 50 °C. However, the stability of catalase incubated at 37 °C in micellar and reverse micellar solutions is lower than that in homogeneous aqueous solution.
Thèses sur le sujet "Micellar catalysi"
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SANZONE, ALESSANDRO. « Towards the development of sustainable materials for organic electronics ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2019. http://hdl.handle.net/10281/241277.
Texte intégralRésumé :
La sintesi e la caratterizzazione di semiconduttori organici (OS) è stata un ambito di ricerca molto sviluppato negli ultimi due decenni. La loro potenziale applicazione per dispositivi come transistor a effetto di campo organici (OFET), diodi organici a emissione di luce (OLED) e celle fotovoltaiche organiche (OPV), ha scatenato un'intensa attività di ricerca in questo campo. Sulla base dei recenti progressi nella tecnologia dei materiali e dei processi e del previsto sviluppo tecnologico futuro, gli esperti sono stati in grado di identificare le sfide chiave di questa tecnologia, per le quali sono necessari importanti sviluppi. La ricerca accademica ha compiuto grandi sforzi per aumentare le prestazioni dei dispositivi, ad esempio se guardiamo l’andamento negli anni della mobilità dei portatori di carica per gli OFET riportata in letteratura possiamo vedere che è aumentata di diversi ordini di grandezza negli ultimi decenni ma spesso sono state trascurate le altre caratteristiche richieste per lo sviluppo industriale di queste tecnologie. Tra le sfide chiave identificate, sono presenti costi e scalabilità. Queste sfide sono direttamente collegate alla tecnica di preparazione e lavorazione dei materiali, in particolare del materiale semiconduttore. In questo lavoro vengono presentati due approcci principali per lo sviluppo di materiali sostenibili per l'elettronica organica, applicati a diverse classi di semiconduttori organici (dichetopirrolopirroli (DPPs), isoindaci (IGs), benzotiadiazoli (BTs) e benzotienobenzotiofeni (BTBTs). Il primo approccio si basa sull’uso della reazione di arilazione diretta piuttosto che le reazioni di accoppiamento più classiche come le reazioni di Suzuki-Miyaura, Kumada e Stille. Il secondo approccio presentato è lo sviluppo di condizioni micellari per la sintesi di semiconduttori organici. Lo studio della reazione di arilazione diretta ha subito un rapido sviluppo negli ultimi anni e sta diventando un'alternativa sempre più valida alle tradizionali reazioni di cross-coupling. La reazione di accoppiamento tradizionali richiedono reagenti organometallici, che in particolare quando sono funzionalizzati, spesso non sono disponibili in commercio o sono relativamente costosi e la loro sintesi prevede l'uso di reagenti infiammabili (es. Butillitio), non stabili e / o altamente tossici (composti organici dello stagno). Pertanto, la reazione di arilazione diretta rappresenta una strategia sintetica più attraente dal punto di vista ambientale ed economico. In particolare il secondo capitolo riporta la sintesi di derivati del BTBT, originali e non, a partire dal BTBT non funzionalizzato per arilazione diretta. Nel capitolo 4 è riportato uno studio sull'ottimizzazione delle condizioni di policondensazione per arilazione diretta per lo sviluppo di un nuovo copolimero a base di dianidride naftalentetracarbossilica per l'applicazione in OFET. Il secondo approccio sviluppato per la sintesi di semiconduttori organici discusso nei capitoli 3 e 4 è la catalisi micellare. Le reazioni micellari sono un argomento ben consolidato nella moderna sintesi organica, nonostante ciò nel campo dei semiconduttori organci gli esempi sono ancora limitati. L'uso della catalisi micellare per semiconduttori organici non è banale infatti solitamente si tratta di molecole fortemente funzionalizzate, altamente cristalline. Nelle diverse sezioni del capitolo 3 e 4 sono esposte diverse strategie sviluppate per l'applicazione della catalisi micellare alle sintesi dei semiconduttori organici. In particolare il capitolo 3 si concentra sulla preparazione dei materiali molecolari a base di derivati del BT e BTBT, invece il capitolo 4 riporta l'ottimizzazione di una preparazione di F8BT, noto semiconduttore organico commerciale, in condizioni micellari.The synthesis and characterization of organic semiconductors (OS) has been a focal research field in the last two decades. Their potential application to large-area and flexible electronic devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs), and organic photovoltaics (OPVs), has sparked intensive research in this field. Organic printed electronics (OPE) is based on the combination of new materials and cost-effective, large area production processes that open up new fields of application. Thinness, light weight, flexibility and potential environmental sustainability are key potential advantages of organic electronics. In fact, several high-tech companies have significantly invested in cheap and high-performance organic-electronic devices, a billion-dollar market that is expected to grow rapidly. Based on the recent progress in materials and process technology and the expected future technology development, the experts were able to identified that key challenges called “Red Brick Walls”, for which major breakthroughs are needed. Academic research has done big effort to increase devices performances, indeed for example if we look charge career mobility for OFET or power efficiency conversion for OPV reported in literature by years we can see that have been increase of different order of magnitude during the last decades but often overlooked the other features required for the OPE industrial development. Indeed among the key challenge identified cost and scalability are present. These challenges are directly linked with the preparation and processing technique of the materials, in particular of the organic semiconductor materials. Here are presented two main approaches in order to development of sustainable materials for organic electronics applied to different OS classes (Diketopyrrolopyrroles (DPPs), Isoindigoes (IGs), Benzothiadiazoles (BTs) and Benzothienobenzothiophenes (BTBTs)): the use of the direct arylation reaction in place of the more classical reactions of Suzuki-Miyaura, Kumada and Stille cross-coupling reactions and the develop of micellar conditions for organic OS synthesis.In particular the second chapter are reported the synthesis of, original and not, [1]benzothieno[3,2-b][1]benzothiophene (BTBT) derivatives, a class of very promising p-materials for OFET, starting from parent BTBT by direct arylation . These are the first examples of late stage functionalization of BTBT scaffold by direct arylation, In chapter 4 is reported a study of optimization of direct arylation polycondensation condition for the develop of a new Naphthalenetetracarboxylic dianhydride-based copolymer for OFET application. The second approach developed for organic OS synthesis reported in chapter 3 and 4 is the micellar catalysis. Micellar reactions are a well established topic in modern organic synthesis, indeed the numbers of reactions reported in literature to date in micellar condition is quite impressive despite this in the field of organic OS the examples are still limited. The use of micellar catalysis for OS material in not trivial indeed organic OS are usually heavily functionalized molecules, highly crystalline and they can interfere with surfactant micellization these lead to low conversion. In the different sections of chapter 3 and 4 are exposed several strategies developed for the application of micellar catalysis to the OS synthesis.
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CERIANI, CHIARA. « Organic Materials for (Opto)electronics introducing Sustainability in Design, Synthesis and Manufacturing ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2022. http://hdl.handle.net/10281/369035.
Texte intégralRésumé :
Il progetto di ricerca si concentra sullo sviluppo di nuove strategie sintetiche per la preparazione di semiconduttori organici stampabili e scalabili industrialmente. A tal fine, è stato introdotto un nuovo metodo sintetico per una facile, economica ed eco-sostenibile produzione di semiconduttori organici coniugati. Oggigiorno, il concetto di sostenibilità è una questione molto importante per le aziende che si impegnano nel rispettare i principi della Green Chemistry al fine di ridurre l'impatto ambientale dei processi chimici.
In questo quadro, la catalisi micellare si è dimostrata un'ottima soluzione permettendo di condurre le reazioni utilizzando l’acqua come l’unico mezzo di reazione generalmente in presenza di piccoli quantitativi di surfattante. Ma purtroppo non sempre la catalisi micellare risulta essere riproducibile e facilmente scalabile industrialmente.
A tal proposito, è stato studiato un sistema auto-emulsionante composto da una miscela di L-α-Lecitina e Tween 80 (TL82) per la preparazione di piccole molecole organiche. La caratteristica unica di questa miscela di tensioattivi offre un nuovo ambiente per l'esecuzione di comuni reazioni di cross-coupling come le reazioni di Suzuki-Miyaura, Sonogashira e Heck in modo riproducibile su larga scala. La versatilità di questo approccio è stata verificata attraverso la sintesi di semiconduttori organici complessi basati su pigmenti insolubili.
La grande attenzione all'introduzione della sostenibilità non riguarda solo la sintesi, ma anche il processing dei materiali per la produzione di dispositivi. È stato introdotto un processo innovativo che consente la preparazione di dispositivi a film sottile ad alte prestazioni a partire da dispersioni acquose di semiconduttori organici sia di tipo p- che n-. La miscela di tensioattivi auto-emulsionante TL82 viene utilizzata sia come mezzo di sintesi che di processing. Questo metodo consente la preparazione di Transistor Organici ad Effetto di Campo utilizzando esclusivamente l’acqua in tutte le fasi di preparazione, ottenendo prestazioni paragonabili ai dispositivi ottenuti dai processi svolti utilizzando solventi organici.
Sono stati inoltre progettati nuovi materiali innovativi performanti per l'(opto)elettronica. In particolari sono stati progettati sia piccole molecole che polimeri coniugati originali ponendo una grande attenzione al selezionamento di materie prime a basso costo, limitando severamente l'utilizzo di sostanze chimiche tossiche e pericolose e progettando tutti i processi per un possibile up-scaling.
In dettaglio, buona parte del lavoro è stata dedicata allo sviluppo di materiali sostenibili per applicazione in concentratori solari luminescenti. Le prestazioni dei materiali sintetizzati sono state confrontate con quelle dei lumofori commercialmente disponibili con caratteristiche spettrali simili. Nel complesso, i nuovi materiali sviluppati mostrano prestazioni comparabili, ma col vantaggio di essere sintetizzati in maniera green e facilmente scalabili industrialmente.
Infine, è stato sviluppato un monomero derivato tiofenico asimmetrico con caratteristiche intrinseche di donatore e accettore al fine di sviluppare uno dei primi esempi di polimero regio-regolare ambipolare.The research focuses on the development of new synthetic routes for the preparation of printable organic semiconductors, devised to be suitable for industrial scaling up. As such, a novel synthetic method for facile, cheap, and environmentally friendly production of π-extended organic semiconductors is explored. The concept sustainability is becoming a very important issue for chemical industries which are approaching green chemistry to reduce the environmental impact of chemical processes. In this frame, micellar catalysis has been demonstrated to be profitably performed in water under very mild conditions in the presence of a bit surfactant. Firstly, a self-emulsifying system L-α-Lecithin-Tween 80 mixture (TL82) is explored for the preparation of organic small molecules. The unique characteristic of this surfactant’s mixture offers a new environment for carrying out common cross coupling reactions such as Suzuki-Miyaura, Sonogashira and Heck cross-couplings in a reproducible up-scale way. The versatility of this approach is verified through the synthesis of complex organic semiconductors such as π-extended insoluble pigments. The emphasis on sustainability is not only applied to the synthesis but also to the processing of the active materials into the final target devices. Indeed, an innovative process is introduced enabling the preparation of high-performance thin film devices starting from waterborne dispersions of p- and n-type organic semiconductors. The TL82 self-emulsifying surfactant’s mixture is used both as the synthesis and processing medium. This method allows the preparation of Organic Field Effect Transistor using exclusively water in all steps with performances comparable to those synthesized and processed using common organic solvents. From the standpoint of the design of innovative materials, additional guidelines beside those aiming at achieving high performances are introduced. Original small molecules and polymers are designed selecting low-cost raw materials, severely the limiting the use of toxic and hazardous chemicals and designing all processes with up-scaling already in mind. These materials find an application in the field of (opto)electronics. An example of a good compromise between a simple design-good performance of a class of materials was investigated. In detail, a good part of the work was dedicated to the technology of luminescent solar concentrators devices, where the performances of the newly designed intrinsically sustainable materials are compared with those commercially available luminophores having similar spectral features. In the overall, we demonstrate comparable performance, but greatly improved sustainability and scalability. The final project was dedicated to the presentation of the first example of D-A regioregular polythiophene with an ambipolar character.
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Maximiano, Flavio Antonio. « Micelas mistas de surfatantes zwiteriônicos e catiônicos : propriedades físico-químicas e efeito na cinética de reação unimolecular ». Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-13052008-153348/.
Texte intégralRésumé :
O interesse por sistemas formados por misturas de surfatantes se deve ao fato destas misturas apresentarem propriedades diferentes, e algumas vezes superiores, às dos surfatantes puros. Neste trabalho foram realizadas, em água e em soluções aquosas de sal, medidas de CMC, constantes de dissociação iônica, concentrações superficiais de contra-íons e entalpias de micelização para misturas de surfatantes zwiteriônicos e catiônicos. Os surfactantes catiônicos utilizados foram: brometo e cloreto de N- hexadecil - N,N,N - trimetil amônio, CTAB(C), e brometo de N- dodecil N,N,N - trimetil amônio, DTAB. Os zwiteriônicos foram: N-hexadecil- N,N-dimetil-3-amônio-1-propanosulfonato, HPS, e N-dodecil- N,N-dimetil-3amônio-1-propanosulfonato, DPS, e n-hexadecil- fosforil colina, HFC. Medidas de tensão superficial, condutividade e entalpia molar de diluição em função da concentração da mistura mostraram que, em água, ocorre primeiro a formação de micelas zwiteriônicas, seguida, com o aumento da concentração total de detergente, da incorporação do surfatante catiônico na fase micelar. A adição de sal facilita a formação de micelas mistas, principalmente nas misturas formadas por surfatantes de maior cadeia hidrocarbônica. Em micelas mistas medidas da concentração superficial de contra-íons por captura química mostraram que a concentração superficial de contra-íons aumenta com a fração molar do detergente catiônico. A concentração superficial de ânions é maior para misturas HPS/CT AB do que para misturas H FC/CTAB, quando a fração molar do detergente zwiteriônico é alta, denotando importância da composição da mistura e do sentido do momento de dipolo da cabeça polar do surfatante zwiteriônico, na capacidade da interface micelar em ligar ânions. Com o objetivo de verificar a extensão na qual a catálise de uma reação unimolecular pode ser controlada por propriedades interfaciais de micelas, foi estudada a reação de descarboxilação do íon 6-nitro benzisoxazol-3- carboxilato que é favorecida em micro-ambientes menos hidratados. Os resultados obtidos nos diferentes sistemas mostraram que misturas HFC/CTAB favorecem mais a reação do que micelas constituídas pelos anfifílicos puros, enquanto que nas misturas HPS/CTAB e DPS/DTAB, a velocidade de descarboxilação aumenta linearmente com a fração molar do surfatante zwiteriônico. A variação das constantes de velocidade com a concentração de detergente para misturas com menos de 30% de surfatante catiônico foi analisada usando o formalismo da pseudo fase, enquanto que as demais foram analisadas usando o formalismo da troca-iônica, levando em conta a dependência de a com a concentração. Este estudo representa a primeira análise integrada de propriedades físico-químicas e cinéticas para um sistema de misturas de detergentes zwiteriônicos e catiônicos. Os dados estruturais, junto com os efeitos cinéticos, fornecem uma descrição detalhada tanto do efeito de interfaces sobre reatividade como da estrutura das micelas mistas.The interest for systems formed by surfactant mixtures is related to the fact that these mixtures exhibit properties that are more interesting, or useful, than those of the isolated components. Some mixtures can, for example, have a lower critical micelle concentration (CMC) or a higher efficiency on the reduction of the surface tension than the components. In this work we determined CMC\'s, ionic dissociation constants, surface counter-ion concentrations and micellization enthalpies for pure zwiterionic and cationic surfactants and their mixtures, in water and in aqueous salt. For this purpose, we used different alkyl chain sizes and varying structures of the polar head groups of zwiterionic detergents thereby changing the dipole moment orientation. In addition the nature of the cationic surfactant counter-ion was varied. Ammonium quaternary detergents (cationic) and sulphobetaines and phosphocholines derivatives (zwiterionic) were used as surfactants. Surface tension, conductivity and isothermal titration calorimetry were used as the main analytical methods. The judicious use of these methods allowed a better understanding of mixed micelle formation. The formation of mixed micelles depended upon several conditions such as: salt concentration, molar fraction of the components and hydrocarbon chain length. Measurements of the surface counter-ion concentrations by chemical trapping demonstrated the importance of mixture composition and of dipole moment orientation on the ability of micellar interface to bind anions. In water, zwitterionic micelles form first and, as the total detergent concentration rises, the positively charged detergent increasingly incorporates into the micellar pseudophase. Salt addition assists mixed micelle formation, especially with longer chain surfactants. Determination of interfacial anion concentration by chemical capture showed that, as expected, the interfacial counterion concentration increases with the molar fraction of the positively charged detergent. Interfacial anion concentration was larger for mixtures of HPS/CTAB when compared with HFC/CTAB mixtures at high molar ratio of the zwitterionic detergent. These results evidence the importance of mixture composition and dipole orientation on the interfacial properties of mixed micelles. The kinetic study of the effects of surfactant mixtures on the rate of a unimolecular decarboxylation reaction using 6-nitro benzisoxazole-3-carboxylate (NBOC) also showed important features of the mixed micellar surface. The rate of the unimolecular NBOC decomposition is extremely sensitive to the hydrogen donating capacity of the solvent at the reaction site. HFC/CTAB mixtures increase the reaction rate more than the single detergent micelles. For HPS/CTAB and DPS/DTAB mixtures the reaction rate increases linearly with the mole fraction of the zwitterionic component. Quantitative kinetic analysis was done using the ion exchange formalism above 30 mole % CTAB and the simple pseudophase model at lower positively charged detergent. This study represents the first integrated analysis of both physicochemical and kinetic properties of zwitterionic/positively charged micelles. The structural data, together with the kinetic effects furnish a detailed description of both micellar interfacial effects on reactivity and mixed micelle formation and properties.
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Gonçalves, Larissa Martins. « Um modelo para detoxificação de organofosforados : efeito de micelas e vesículas na oximólise de p-nitrofenildifenilfosfato ». Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/46/46131/tde-02022007-171907/.
Texte intégralRésumé :
Oximas têm sido extensivamente usadas como antídoto para envenenamento por organofosforados e como desontaminante. Micelas e vesículas, utilizadas como catalisadores e transportadores de drogas, constituem agentes potenciais para tratamento e descontaminação. Neste trabalho descrevemos a reação de p-Nitrofenildifenilfosfato (PNPDPP), um substrato modelo para organofosforado, com: acetofenoxima (I); ácido 10- fenil-10-hidroxiiminodecanóico (II); 4-(9-carboxinonanil)-1-(9-carboxi-1-hidroiimino nonanil) benzeno (III); cloreto de N-dodecilpiridina (IV); cloreto N-metilpiridina 2-aldoxima (V), na presença de micelas catiônicas e zwitteriônicas de cloreto de hexadeciltrimetilamônio, CTAC e N-Hexadecil-N,N-dimetil-1-propano sulfonato, HPS, respectivamente, e vesículas catiônicas de dioctadecildimetilamônio, DODAC. O pKa aparente, pKap, das oximas em agregados de anfifilicos, a constante de velocidade de segunda ordem de oximólise em micelas ou vesículas, km, e as constantes de velocidade observadas para a oximólise de PNPDPP, kobs, foram determinadas espectrofotometricamente, a pH constante, variando-se a concentração dos anfifílicos. Os resultados foram analisados usando as teorias: modelo de pseudofase (PP) e modelo de pseudofase com considerações de troca iônica (PIE), descrita na literatura pelo nosso grupo. As constantes de segunda ordem para oximólise de PNPDPP em água, kox, determinadas foram 6,5 M^-1 min^-1 (I, II e III) e 2,8 M^-1 min^-1 (IV e V). O kobs máximo em micelas e vesículas, kobsmax, e o kobs em água, kw, no mesmo pH, foram utilizadas para calcular o fator de aceleração máxima, AF, para cada anfifílico (AF = kobsmax/kw). Os agregados catalisam a decomposição de PNPDPP e os valores de AF (e km) foram da ordem de 10^4 (32 min^-1), 10^4 (125 min^-1) e 10^6 (80 min^-1) para a reação da oxima IV com CTAC, HPS e DODAC, respectivamente. A análise quantitativa da dependência da concentração de agregados anfifílicos na oximólise mostrou um considerável aumento da constante de velocidade da reação produzido por micelas e vesículas (maior que 8 x 10^6 vezes). Esse efeito é parcialmente devido a: concentração local dos reagentes, efeitos nos pKas dos nucleófilos e, mais importante, mudança na reatividade intrínseca das oximas.Oximes have been extensively used as antidotes and decontaminants of organophosphates. Micelles and vesicles, catalysts and drug transport agents, constitute potential vehicles for Oxime treatment. Here we describe the reaction of p-nitrophenyldiphenylphosphate (PNPDPP) with: acetophenoxime (I); 10-phenyl-10-hydroxyiminodecanoic acid (II); 4-(9-carboxynonanyl)-1-(9-carboxy-1-hydroyiminononanyl) benzene (III); N-dodecylpyridinium chloride (IV); N-methylpyridinium 2-aldoxime chloride (V), in the presence of cationic and zwitterionic micelles, hexadecyltrimethylammonium chloride, CTAC and N-Hexadecyl-N,N-dimethyl-1-propanesulfate, HPS, respectively, and cationic vesicles of dioctadecyldimethylammonium, DODAC. The apparent pKa, pKap, of the oximes in the amphiphile aggregates, the second order rate constants of oximolysis in micelles and vesicles, km, and the observed rate constants for PNPDPP oximolysis, kobs, were determined spectrophotometrically at constant varying amphiphilic concentrations. The results were analyzed using the pseudo-phase theory (PP) and pseudo-phase / ion exchange (PIE). The second order rate constant for (uncatalyzed) oximolysis of PNPDPP were 6.5 M^-1 min^-1 (I, II and III) and 2.77 M^-1 min^-1 (IV and V). From the maximum value of kobs in micelles and vesicles, kobsmax, and the value of kobs in water, kox, at the same pH, the maximum acceleration factor, AF, were calculated (AF = kobsmax / kw). The amphiphiles catalyzed the oximolysis of PNPDPP and the values of AF (and km) were ca 10^4 (32 min^-1), 10^4 (125 min^-1) and 10^6 (80 min^-1) for the reactions of Oxime IV in CTAC, HPS and DODAC, respectively. Quantitative analysis of the amphiphile concentration-dependence of rates demonstrated that the considerable rate increase produced by micelles and vesicles on the rate of oximolysis (up to 8 x 10^6 fold) is partly due to reagent concentration in the aggregate, effects on the pKas of the nucleophiles and, more importantly, catalysis.
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Diego-Castro, Michael John. « Micellar media and the catalysis of the Diels-Alder reactions ». Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312963.
Texte intégral
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Gwicana, Sakumzi. « Micellar-enhanced ultrafiltration of palladium and platinum anions ». Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/518.
Texte intégralRésumé :
The project was concerned with studying the capability of a micellar-enhanced ultrafiltration system (MEUF) to remove platinum group metal ions namely Pt (lV) and Pd (ll) chloro anions from aqueous industrial waste effluents. South Africa has the world’s largest reserves of platinum group metals (PGMs) and other valuable metals such as manganese, chrome ores, titanium minerals etc. which are required for new automotive and other technologies, including fuel cells, catalytic converters and lighter components. The consistent loss with the industrial waste stream and the toxicological effects of these precious metals led to the need to develop new and effective methods to recover them from industrial waste effluents. With such a wide variety of fields where these PGMs are used and the failure of the traditional techniques namely sedimentation, fermentation etc. to effectively reduce or recover these highly toxic and precious metal ions prior to discharging industrial waste effluents, it is necessary to explore other techniques such as membrane technology that can be used to recover these valuable species from industrial waste streams. The present study involved the use of a cationic surfactant, viz cetylpyridinium chloride, which was introduced into an aqueous solution containing palladium and platinum metal anions. The surfactant forms charged micelles above a certain critical concentration value. The metal anions adsorb onto the available oppositely charged sites on the micelle surfaces and are then able to be retained by a suitable membrane. Hollow fibre ultrafiltration membranes with the MWCO of +/- 10 kD and +/-30nm pore size were used as a filter component in this study. For this MEUF system to be effective, it was vital that the anionic metal ion species adsorbed sufficiently onto the available oppositely charged sites of the micelles and that the micelles were retained efficiently by the membrane. Results obtained during the investigation made it possible to make certain predictions about the micellisation process. It was also found that, it was not only the metal ion: surfactant (M:S) ratio that was critical, but the presence of other electrolytes in the aqueous stream proved to have a huge impact on the capability of the MEUF system. Findings of this research study showed that the MEUF system using cetylpyridinium chloride (CPC) can be used to recover or retain Pt (lV) and Pd (ll) anions from industrial waste effluents. It was also found that PtCl6 2-, due to its greater adsorption capabilities onto the micelle surface than PdCl4 2- or PdCl3(H2O)-, was preferentially retained in neutral medium. This may be exploited as a possible means of separating the two metal ions. The developed system offers the following advantages over some traditional and current methods: simplified unit operation line flow process, smaller amounts of chemical usage and no solid toxic sludge to be disposed of. Applications of this work could be of vital importance in catalytic converter recycling, especially in Port Elizabeth where extensive automobile parts manufacturing occurs.
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Tondo, Daniel Walker. « Síntese e estudos físico-químicos de surfactantes dipolares iônico ». reponame:Repositório Institucional da UFSC, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/94804.
Texte intégralRésumé :
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2011Made available in DSpace on 2012-10-25T16:27:48Z (GMT). No. of bitstreams: 1 288270.pdf: 3875174 bytes, checksum: 2d983bc7cb93aa663182a095ae25dc76 (MD5)
Este trabalho aborda o estudo físico-químico de surfactantes dipolares iônicos ou zwiteriônicos, tendo como foco a investigação da ligação de íons em micelas dipolares iônicas. Inicialmente, é descrito o estudo de interação entre diversos íons e micelas de sulfobetaínas utilizando técnicas de eletroforese capilar, titulação calorimétrica isotérmica (ITC) e de espectroscopia UV/Vis, através de estudos cinéticos e de titulação espectrofotométrica. Os estudos de ITC, como a cinética de hidrólise ácida do HFD e a titulação espectrofotométrica do HNA mostraram que a ligação ânion-micela segue a ordem: Cl- < Br- < NO3- < BF4- < Tos- < ClO4- < PF6- que é consistente com a série de Hofmeister. Além disso, o estudo cinético também mostrou que o ânion ClO4- liga-se preferencialmente às sulfobetaínas de maior cadeia hidrofóbica seguindo a ordem: SB3-10 < SB3-12 < SB3-14 < SB3-16. Os estudos cinéticos e de eletroforese capilar mostraram que a ligação entre o ânion ClO4- e micelas de SB3-14 é inibida com a adição de cátions e o grau de inibição aumenta com a valência do cátion na ordem: monovalente < bivalente < trivalente. Em seguida, é descrita a síntese de quatro surfactantes dipolares iônicos que contem um núcleo imidazólico e cadeias alquílicas com 10, 12, 14, e 16 átomos de carbonos, os quais diferem das sulfobetaínas apenas na porção catiônica. Parâmetros físico-químicos como número de agregação (Nagg), concentração micelar crítica (CMC) e solubilidade foram determinados para os novos surfactantes com o uso de técnicas de espectroscopia de fluorescência, tensiometria e espectroscopia UV/Vis respectivamente. Apesar da alta solubilidade das sulfobetaínas, a substituição do grupo amônio por um grupo imidazólico, como nos surfactantes sintetizados, causou um decréscimo acentuado na solubilidade devido à introdução de um grupo cíclico, rígido e aromático, no entanto, a adição de eletrólitos provocou um aumento intenso na solubilidade. Dos quatro surfactantes obtidos, foi selecionado o ImS3-14 para estudos da ligação de ânions em micelas, os quais foram realizados de maneira semelhante às sulfobetaínas, revelando que a preferência das micelas de ImS3-14 pelos ânions estudados segue a ordem: Cl- < Br- < NO3- < Tos- < ClO4-, que é a mesma observada para as sulfobetaínas. Por fim, foram realizados estudos teóricos computacionais e de eletroforese capilar, comparando a sulfobetaína SB3-14 e o novo surfactante ImS3-14. Os cálculos ab initio mostraram que as estruturas de ambos os surfactantes são muito similares, mas existem diferenças de distribuição de carga no grupo cabeça. O potencial zeta máximo para o ImS3-14 na presença do ânion perclorato é superior ao da SB3-14 nas mesmas condições, mostrando a superioridade do ImS3-14 em ligar ânions comparado à sulfobetaína SB3-14.
This work approaches the physical chemistry study of the dipolar ionic or zwitterionic surfactants, focusing on the investigation of ion binding to dipolar ionic micelles. Initially, a study concerning the interaction between several ions and sulfobetaine micelles is described using techniques of capillary electrophoresis, isothermal titration calorimetry (ITC) and UV/Vis spectroscopy. In this sense, all the experiments including ITC, the kinetic of hydrolysis of the HFD and the spectrophotometric titration of the HNA showed that binding of anions to micelles follows the order: Cl- < Br- < NO3- < BF4- < Tos- < ClO4- < PF6- which is in agreement with the Hofmeister series. Besides, the kinetic study also showed that ClO4- anion preferentially binds to sulfobetaine with higher hydrophobic chain following the order: SB3-10 < SB3-12 < SB3-14 < SB3-16. Capillary electrophoresis as well as kinetic studies showed that the binding between ClO4- and SB3-14 micelles is inhibited by cation addition and the inhibition degree depends upon the cation valency in the order: monovalent < bivalent < trivalent. Four new dipolar ionic surfactants were synthesized containing imidazole moiety and alkyl chains with 10, 12, 14 and 16 carbon atoms, and they differ from sulfobetaines only in the cationic portion. Physical-chemical properties such as aggregation number (Nagg), critical micelle concentration (CMC) and solubility were obtained for the new surfactants using techniques of fluorescence spectroscopy, surface tension measurements and UV/Vis spectroscopy, respectively. Despite expected high sulfobetaine solubilities, replacement of ammonium by an imidazolium group, as in the syntesized surfactants, sharply decreased solubility due to the ciclic, rigid and aromatic system, however, addition of electrolytes strongly increase the solubility. Among the sintesized surfactants, the ImS3-14 was selected for the evaluation of anion binding to micelles and the studies were carried out similarly to those for sulfobetaines, disclosing a preference of ImS3-14 micelles for the studied anions in the order: Cl- < Br- < NO3- < Tos- < ClO4-, which is the same sequence observed for sulfobetaines. Finally, theoretical and computational studies as well as capillary electrophoresis were performed comparing the sulfobetaine SB3-14 and the ImS3-14. Ab initio calculations showed similar structures for both surfactants, but diferences for charge distribution of the headgroups were observed. The maximal zeta potential for ImS3-14 in the presence of ClO4- anion is greater compared to SB3-14 in the same conditions, showing the superiority of ImS3-14 in bind anions.
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Couderc, Sabine. « Micelles d'oximates hexadecyltrimethylammonium : propriétés et conjonction des catalyses micellaire et supernucléophile pour la destruction par hydrolyse des triesters phosphoriques ». Versailles-St Quentin en Yvelines, 1999. http://www.theses.fr/1999VERS0010.
Texte intégralRésumé :
L' @hydrolyse des triesters phosphoriques est étudiée au plan cinétique dans l'eau et dans les solutions de sels d'hexadecyltrimethylammonium en présence d'ions oximate catalytiques. En l'absence de tensioactif, les ions oximate sont des nucléophiles catalyseurs plus efficaces que d'autres nucléophiles de même basicité. Cela provient de l'effet dénommé effet. Par suite d'un effet de saturation des nucléophiles, l'extra réactivité est maximale pour des ions oximate dont le pk a est proche de 8. Les micelles cationiques accentuent fortement l'effet catalytique par un facteur atteignant 10 3, l'augmentation de vitesse étant optimale lorsque les contre-ions du tensioactif sont les ions oximate eux-mêmes, C'est à dire pour les oximates d'hexadecyltrimethylammonium, c 1 6ta-ox, préparés dans cette thèse. Il est montré que les solutions de c 1 6ta-ox présentent de nombreux avantages pour la mise en oeuvre des processus dits de décontamination des esters organophosphorés et il est proposé que les solutions de c 1 6ta-ox soient utilisées pour la décontamination douce (à pH neutre) des muqueuses. Par exemple, le pesticide paraoxon (3) defaible réactivité est complètement hydrolysé au bout de quelques minutes. La catalyse micellaire par des amphiphiles dans lesquels un groupe oximate a été greffé de façon covalente ne sont pas plus efficaces que des tensioactifs pour lesquels les ions oximate ne sont associés aux micelles que de façon lâche. Les propriétés physico-chimiques des micelles de c 1 6ta-ox sont examinées à partir des données de concentrations micellaires critiques, de conductimètrie et de pH. Une attention particulière est apportée à l'influence des concentrations en tensioactif et en sel sur le degré d'association entre les micelles et les ions oximate. Plusieurs améliorations des modèles cinétiques de la catalyse micellaire sont suggéréesL'hydrolyse des triesters phosphoriques est etudiee au plan cinetique dans l'eau et dans les solutions de sels d'hexadecyltrimethylammonium en presence d'ions oximate catalytiques. En l'absence de tensioactif, les ions oximate sont des nucleophiles catalyseurs plus efficaces que d'autres nucleophiles de meme basicite. Cela provient de l'effet denomme effet. Par suite d'un effet de saturation des nucleophilies, l'extrareactivite est maximale pour des ions oximate dont le pk a est proche de 8. Les micelles cationiques accentuent fortement l'effet catalytique par un facteur atteignant 10 3, l'augmentation de vitesse etant optimale lorsque les contre-ions du tensioactif sont les ions oximate eux-memes, c'est-a-dire pour les oximates d'hexadecyltrimethylammonium, c 1 6ta-ox, prepares dans cette these. Il est montre que les solutions de c 1 6ta-ox presentent de nombreux avantages pour la mise en oeuvre des processus dits de decontamination des esters organophosphores et il est propose que les solutions de c 1 6ta-ox soient utilisees pour la decontamination douce (a ph neutre) des muqueuses. Par exemple, le pesticide paraoxon (3) de faible reactivite est completement hydrolyse au bout de quelques minutes. La catalyse micellaire par des amphiphiles dans lesquels un groupe oximate a ete greffe de facon covalente ne sont pas plus efficaces que des tensioactifs pour lesquels les ions oximate ne sont associes aux micelles que de facon lache. Les proprietes physicochimiques des micelles de c 1 6ta-ox sont examinees a partir des donnees de concentrations micellaires critiques, de conductimetrie et de ph. Une attention particuliere est apportee a l'influence des concentrations en tensioactif et en sel sur le degre d'association entre les micelles et les ions oximate. Plusieurs ameliorations des modeles cinetiques de la catalyse micellaire sont suggerees
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Peroza, Meza Carlos Arturo. « Factors affecting the alkaline hydrolysis of carbaryl in the presence of cationic surfactants ». Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/6248.
Texte intégralRésumé :
Alkaline degradation of Carbaryl in the presence of CTAB micelles has been reported as the most efficient method; however, the factors accounting for it are not yet clear. The main objective of this work was to study some of the factors affecting the alkaline degradation of Carbaryl in the presence of cetyl trimethylammonium bromide (CTAB). Three specific aims were researched in order to address the main objective.
Solubility studies, UV-vis, fluorescence, and 1D-HNMR and 2D-HNMR spectroscopies were used to research the solubilization of carbaryl in CTAB micelles. Solubility studies showed that carbaryl partitions into CTAB micelles with a binding constant of 553 ± 8 M-1, and each mole of micellized surfactant incorporates about 0.336 moles of carbaryl. Spectroscopy studies showed that carbaryl does not interact electrostatically with micelles but does through van der Waals interactions. 1D-HNMR and 2D-HNMR indicated solubilization in the Stern layer, oriented with its hydrophilic moiety towards the Goüy-Chapman layer and the hydrophobic moiety towards the core of the micelle.
Kinetic studies as a function of the surfactant concentration along with micellar kinetic models were used to calculate micellar rate constants (k’M) for each of four different cationic surfactants: cetyl trimethylammonium hydroxide (CTAOH), cetyl trimethylammonium bromide (CTAB), cetyl trimethylammonium chloride (CTACl), and cetyl pyridinium chloride (CPCl), and compared to the corresponding rate constants (k’W) in water; the results in all cases showed k’M / k’W > 1. This fact led to the conclusion that additional factors beyond solubilization of substrates are playing a role. Solubility studies revealed the following binding constant order and solubilization capacity order: CPCl > CTAOH ≈ CTAB > CTACl, CPCl > CTAOH ≈ CTAC > CTAB, indicating that for CPCl, Coulombic interactions, such as charge-transfer complexes, may be favoring the concentration effects, while for other surfactants, such as CTAOH, the [–OH] as the micelle counterion increases Carbaryl’s concentration in the Stern layer compared to its bulk concentration. In contrast, large, weakly-hydrated polarizable ions such as Br– displace hydrophilic ions, providing less enhancement.
Kinetic experiments as a function of the surfactant head’s charge led to the conclusion that cationic and zwitterionic surfactants have a catalytic effect of the alkaline hydrolysis of carbaryl, while nonionic and anionic surfactants have inhibitory effects: kobs (cationic) > kobs (zwitterionic) > kobs(nonionic) > kobs (anionic). A similar order for solubility parameters (Ks and SC) was observed from equilibrium solubility studies. Experiments as a function of the polarity of the medium in the presence of both polar and nonpolar solvents showed that the hydrolysis rate is inversely proportional to the medium polarity. Ionic strength experiments showed that the hydrolysis rate is inversely proportional to the ion concentration.
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Meggiato, Francesca <1989>. « catalisi micellare nella formazione di legami C-C e C-O ». Master's Degree Thesis, Università Ca' Foscari Venezia, 2017. http://hdl.handle.net/10579/10470.
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Micellar catalysis. Boca Raton : CRC/Taylor & Francis, 2007.
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Peebles, Jason A. Alkane oxidations in a micellar/mitalloporphyrin catalytic system. Ottawa : National Library of Canada, 1994.
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R, Hill Aubrey, et Orgel Leslie E, dir. Catalysis of the oligomerization of o-phospho-serine, aspartic acid, or glutamic acid by cationic micelles. [Washington, D.C : National Aeronautics and Space Administration, 1997.
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Khan, Mohammad Niyaz. Micellar Catalysis. Taylor & Francis Group, 2020.
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Khan, Mohammad Niyaz. Micellar Catalysis. Taylor & Francis Group, 2006.
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Khan, Mohammad Niyaz. Micellar Catalysis. Taylor & Francis Group, 2010.
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Khan, Mohammad Niyaz. Micellar Catalysis. Taylor & Francis Group, 2006.
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Khan, Mohammad Niyaz. Micellar Catalysis (Surfactant Science). CRC, 2006.
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Fendler, Janos. Catalysis in Micellar and Macromoleular Systems. Elsevier Science & Technology Books, 2012.
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Moroi, Yoshikiyo. « Micellar Catalysis ». Dans Micelles, 195–209. Boston, MA : Springer US, 1992. http://dx.doi.org/10.1007/978-1-4899-0700-4_11.
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Nuyken, Oskar, Ralf Weberskirch, Thomas Kotre, Daniel Schönfelder et Alexander Wörndle. « Polymers for Micellar Catalysis ». Dans Polymeric Materials in Organic Synthesis and Catalysis, 277–304. Weinheim, FRG : Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527601856.ch6.
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Kondo, Hiroki. « Micellar Catalysis of Pyridoxal-Dependent Reactions ». Dans Biochemistry of Vitamin B6, 347–52. Basel : Birkhäuser Basel, 1987. http://dx.doi.org/10.1007/978-3-0348-9308-4_61.
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Oehme, G., I. Grassert et N. Flach. « Asymmetric Complex Catalysis in Micellar Systems ». Dans Aqueous Organometallic Chemistry and Catalysis, 245–57. Dordrecht : Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0355-8_24.
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Manoury, Eric, Florence Gayet, Franck D’Agosto, Muriel Lansalot, Henri Delmas, Carine Julcour, Jean-François Blanco, Laurie Barthe et Rinaldo Poli. « Core-Cross-Linked Micelles and Amphiphilic Nanogels as Unimolecular Nanoreactors for Micellar-Type, Metal-Based Aqueous Biphasic Catalysis ». Dans Effects of Nanoconfinement on Catalysis, 147–72. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-50207-6_7.
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Orlich, Bernhard, et Reinhard Schomäcker. « Enzyme Catalysis in Reverse Micelles ». Dans History and Trends in Bioprocessing and Biotransformation, 185–208. Berlin, Heidelberg : Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/3-540-44604-4_6.
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Zuev, Yu F., B. Z. Idiyatullin, V. D. Fedotov, A. B. Mirgorodskaya, L. Ya Zakharova et L. A. Kudryavtseva. « Structural Factors in Micellar Catalysis : NMR Self-Diffusion Study ». Dans Magnetic Resonance in Colloid and Interface Science, 649–54. Dordrecht : Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0534-0_68.
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Sirovski, F. S. « Phase-Transfer and Micellar Catalysis in Two-Phase Systems ». Dans ACS Symposium Series, 68–88. Washington, DC : American Chemical Society, 1997. http://dx.doi.org/10.1021/bk-1997-0659.ch006.
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Gaboriaud, R., J. Lelièvre, G. Charbit et F. Dorion. « Reaction Rate Control by Salt Effects in Micellar Catalysis ». Dans Surfactants in Solution, 637–50. Boston, MA : Springer US, 1986. http://dx.doi.org/10.1007/978-1-4615-7981-6_7.
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Rubingh, Donn N., et Mark Bauer. « Lipase Catalysis of Reactions in Mixed Micelles ». Dans Mixed Surfactant Systems, 210–26. Washington, DC : American Chemical Society, 1992. http://dx.doi.org/10.1021/bk-1992-0501.ch012.
Texte intégralActes de conférences sur le sujet "Micellar catalysi"
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Daiguji, Hirofumi. « Transport and Adsorption Phenomena in Mesoporous Silica ». Dans ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73137.
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The analysis and control of transport phenomena in fluidic nanopores and nanochannels is important in applications such as biochemical analysis, power generation and environmental protection. A unique aspect of nanofluidics is that the relevant length scale is comparable to the range of various surface and interfacial forces in liquids (such as electrostatic, van der Waals and steric interactions). Thus, to obtain an adequate description of transport phenomena in nanospace, it is necessary to understand the discreteness of molecules, especially when the size decreases to 2 nm. Micelle-templated mesoporous silicas (MPSs) possess highly ordered structures such as 2D hexagonal and 3D cubic structures and pores within the 2–50 nm range. In particular, 2D hexagonal films that generally have pore channels parallel to the surface plane have been widely synthesized by using various types of template molecules. If the pore channels of such materials are aligned in a certain direction, these materials can be employed for various purposes such as the fabrication of oriented nanowires, optoelectronic devices, recording media, selective separations, and nanofluidic systems. 3D cubic structures give large surface areas and become good candidates for highly efficient catalysts and sensors. Advances in the synthesis, measurement and analysis of nanotubes and nanochannels have allowed ion and liquid transport to be routinely examined and controlled in spaces with dimensions that range from 10 to 100 nm. The ability to now explore transport and adsorption phenomena in confined spaces of around 2 nm offers a range of possibilities. We have investigated several unique transport and adsorption phenomena in mesopores measuring a few nanometers in diameter, including nonlinear I–V curves of ionic current passing through MPS thin films filled with aqueous solutions, humidity-dependent adsorption rate of water into MPS, and the reduction of melting and freezing temperature of water in MPS.
Rapports d'organisations sur le sujet "Micellar catalysi"
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Betty, Rita G., Mark D. Tucker, Gretchen Taggart, Mark K. Kinnan, Crystal Chanea Glen, Danielle Rivera, Andres Sanchez et Todd Michael Alam. Enhanced Micellar Catalysis LDRD. Office of Scientific and Technical Information (OSTI), décembre 2012. http://dx.doi.org/10.2172/1096958.
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Abrevaya, H. Micelle-derived catalysts for extended Schulz-Flory. Office of Scientific and Technical Information (OSTI), janvier 1986. http://dx.doi.org/10.2172/7191954.
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Abrevaya, H. Micelle-derived catalysts for extended Schulz-Flory. Office of Scientific and Technical Information (OSTI), janvier 1985. http://dx.doi.org/10.2172/7191957.
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Abrevaya, H. Micelle-derived catalysts for extended Schulz-Flory. Office of Scientific and Technical Information (OSTI), janvier 1986. http://dx.doi.org/10.2172/7027360.
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Abrevaya, H. Micelle-derived catalysts for extended Schulz-Flory. Office of Scientific and Technical Information (OSTI), janvier 1986. http://dx.doi.org/10.2172/6945672.
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Abrevaya, H. Micelle-derived catalysts for extended Schulz-Flory. Office of Scientific and Technical Information (OSTI), janvier 1986. http://dx.doi.org/10.2172/6995148.
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Abrevaya, H. Micelle-derived catalysts for extended Schulz-Flory. [Quarterly report], January 1, 1986--March 31, 1986. Office of Scientific and Technical Information (OSTI), décembre 1986. http://dx.doi.org/10.2172/10190418.
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Abrevaya, H. Micelle-derived catalysts for extended Schulz-Flory. [Quarterly report], April 1, 1986--June 30, 1986. Office of Scientific and Technical Information (OSTI), décembre 1986. http://dx.doi.org/10.2172/10190434.
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Author, Not Given. Micelle-derived catalysts for extended Schulz-Flory. Technical progress report, April 1, 1985--June 30, 1985. Office of Scientific and Technical Information (OSTI), décembre 1985. http://dx.doi.org/10.2172/10190247.
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Abrevaya, H. Micelle-derived catalysts for extended Schulz-Flory. Technical progress report, October 1, 1985--12/31/85. Office of Scientific and Technical Information (OSTI), décembre 1985. http://dx.doi.org/10.2172/10190436.
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