Dissertations / Theses: 'Micellar catalysi'

1

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

2

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

3

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/.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

4

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/.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

5

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Gwicana, Sakumzi. "Micellar-enhanced ultrafiltration of palladium and platinum anions." Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/518.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

7

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.

Full text

Abstract:

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2011 Made 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.

APA, Harvard, Vancouver, ISO, and other styles

8

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.

Full text

Abstract:

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 suggérées L'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

APA, Harvard, Vancouver, ISO, and other styles

9

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

10

Meggiato, Francesca <1989&gt. "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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Lambert, Romain. "Nouveaux copolymères et nanostructures dérivés de liquides ioniques à base d'imidazoliums : applications en catalyse et comme additifs conducteurs ioniques." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0306/document.

Full text

Abstract:

Des poly(liquides ioniques) (PILs) arrangés sous la forme de copolymères statistiques,de nanoparticules à chaine unique ou bien sous la forme de copolymères à blocs autoassemblés ont été employés comme précurseurs de carbènes N-hétérocycliques (NHC)s à des fins de catalyses organiques ou organométalliques. L’introduction d’anions acétate dans des unités PIL dérivés d’imidazolium permet la génération in situ de NHCs actifs en catalyse. Les nanoparticules composées d’une chaine unique polymère repliée sur elle-même (SCNP) ont été spécialement conçues selon deux stratégies impliquant, d’une part, une réaction d’autoquaternisation entre groupements fonctionnels antagonistes portés par la chaine et, d’autre part, une réaction de complexation organométallique à l’aide d’un sel de palladium. Dans lesdeux cas, les chaines polymères ont été obtenues par polymérisation contrôlée (méthode RAFT). Les copolymères à blocs amphiphiles comportant un bloc PIL fonctionnalisé par du palladium ont été synthétisés par polymérisation RAFT et auto-assemblés dans l’eau sous forme de micelles.Un effet de confinement des sites catalytiques a clairement été démontré à travers des réactions de catalyse pour les couplages de Suzuki et de Heck dans l’eau, avec un gain cinétique très net par rapport à des homologues non micellisés, en plus d’une grande facilité de recyclage de ces supports micellaires.Enfin, des copolymères à blocs à base de PIL-benzimidazolium à contre anion bis(trifluoromethane)-sulfonylimide de lithium ont été développés comme agents dopants conducteurs ioniques de matrices structurantes PS-b-PEO. Des mélanges configurés en films minces avec une quantité minimale d’agent dopant ont conduit dans certaines conditions à des valeurs optimales de conductivité ionique grâce à une nano structuration des films à longue distance Poly(ionic liquid)s (PILs) in the form of random copolymers, single chain nanoparticles(SCNPs), or self assembled block copolymers have been used as N-heterocyclic carbenes(NHCs) precursors for the purpose of organic and organometallic catalysis. Introducing acetate derivative counter anion in imidazolium based PIL units enable in situ generation of catalyticallyactive NHC. SCNPs have been specially designed along two strategies including, firstly, a self quaternization reaction involving two antagonists groups supported on to the polymer chain and,secondly, an organometallic complexation featuring palladium salt. Both polymeric precursors were obtained using RAFT as controlled polymerization method. Amphiphilic block copolymers composed of a PIL block functionalized by palladium have been synthesized by RAFT and self-assembled in water, leading to micellar structures. Confinement effect has been demonstrated through Suzuki and Heck coupling in water showing kinetic gain compared to molecular homologue in addition to an easier recycling method.Finally, PIL-benzimidazolium based block copolymers with lithium bis(trifluoromethane)-sulfonylimide anion have been developed as ionic conductor doping agent for PS-PEO matrix. Thin films blends with minimum doping agent amount led to optimum ionic conductivity owing tolong range order

APA, Harvard, Vancouver, ISO, and other styles

12

Ouarti, Nadia. "Tampons faiblement basiques en milieu micellaire : application à l'optimisation de la catalyse micellaire de la déphosphorylation d'un ester organophosphoré hydrophobe par des oximates." Paris 7, 2001. http://www.theses.fr/2001PA077228.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Yu, Xiaoqian [Verfasser]. "Synthesis of organocatalysts immobilized on temperatureresponsive polymers for application in micellar catalysis / Xiaoqian Yu." Paderborn : Universitätsbibliothek, 2018. http://d-nb.info/1167856465/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Frescura, Vera Lucia Azzolin. "Estabilidade cinetica e termodinamica de benzilcobalamina, em presença de detergentes." reponame:Repositório Institucional da UFSC, 1989. http://repositorio.ufsc.br/xmlui/handle/123456789/75539.

Full text

Abstract:

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e Matematicas Made available in DSpace on 2012-10-16T02:14:25Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T16:11:52Z : No. of bitstreams: 1 78933.pdf: 1921988 bytes, checksum: 187026bb86e8eeb4524646ac009c92e9 (MD5) Foram estudadas as velocidades de decomposição térmica da ligação cobalto-carbono na benzilcobalamina em solução aquosa de brometo de cetiltrimetilamônio (CTABr), dodecilsulfato de sódio (SDS), decilfosfato mono e dissódico (NaDP e Na2DP) em função do pH e da concentração de detergente. O efeito de surfactantes no equilíbrio de protonação para o benzimidazol é aquele previsto baseado nos efeitos eletrostáticos (pKaapp = 7,0 em SDS, pKa = 4,25 em água, pKaapp = 4,0 em CTABr; pKaapp = 6,5 em NaDP e pKaapp = 9,0 em Na2DP). Foram calculados os parâmetros termodinâmicos de ativação para a decomposição térmica da benzilcobalamina na presença dos diferentes surfactantes a partir dos valores encontrados para as constantes de velocidade de primeira ordem, nas diferentes temperaturas. Enquanto que a entalpia de ativação varia de 4 Kcal/mol, e a energia livre de ativação 2 Kcal/mol, a entropia de ativação varia de 10 cal/mol.K, indicando efeitos compensatórios envolvendo entalpias e entropias de ativação. O aumento na estabilidade cinética e termodinâmica observado para a benzilcobalamina em presença de micelas catiônicas e aniônicas foi explicado em termos da incorporação dos derivados da vitamina B12 na pseudo fase micelar e reatividade diferencial pelo impedimento da coordenação da molécula de benzimidazol.

APA, Harvard, Vancouver, ISO, and other styles

15

Roman, Maria Ada Lezcano. "Hidrolise basica da 2.2.2-tricloro-1-fenilectanona em micelas normais." reponame:Repositório Institucional da UFSC, 1989. http://repositorio.ufsc.br/xmlui/handle/123456789/75541.

Full text

Abstract:

Dissertação (mestrado) - Universidade Federal de Santa Catarina. Centro de Ciencias Fisicas e Matematicas Made available in DSpace on 2012-10-16T02:15:32Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T16:26:56Z : No. of bitstreams: 1 78936.pdf: 1915711 bytes, checksum: 8404173fee0c88c54e34ed1c764ebc2c (MD5) A hidrólise básica da 2,2,2-tricloro-1-feniletanona (TCA) foi estudada em soluções aquosas na presença de surfactantes catiônicos, aniônicos e não-iônicos em diferentes valores de pH. Os dados cinéticos foram analisados segundo o modelo de troca iônica. O brometo de hexadeciltrimetilamônio (CTAB), catalisa a reação cerca de 100 vezes com relação à água pura e o cloreto de hexadeciltrimetilamônio (CTAC1), catalisa a reação 9% a mais que CTAB. Na presença dos sais KNO3 e KBr, foi constatada uma grande inibição na hidrólise da TCA, sendo maior a inibição na presença de KNO3.

APA, Harvard, Vancouver, ISO, and other styles

16

Bertoncini, Clelia Rejane Antonio. "Efeito de aditivos em micelas cationicas." reponame:Repositório Institucional da UFSC, 1989. http://repositorio.ufsc.br/xmlui/handle/123456789/75544.

Full text

Abstract:

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e Matematicas Made available in DSpace on 2012-10-16T02:16:38Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T16:26:26Z : No. of bitstreams: 1 78937.pdf: 2437398 bytes, checksum: 1ee043098f93193a5fadb8fd46ed69b3 (MD5) Micelas catiônicas de brometo e hidróxido de cetiltrietilamônio (CTEABr e CTEAOH) têm suas propriedades físico-químicas afetadas pela adição de n-butanol (BuOH). Através de medidas de condutividade, a 25oC, foram determinados os valores de CMC e a destes detergentes, em soluções aquosas na presença de BuOH. A CMC diminui em baixas concentrações e aumenta em altas concentrações de BuOH, enquanto que o valor de a aumenta continuamente com adição de BuOH. Os efeitos da adição de BuOH e NaBr nas propriedades catalíticas de CTABr e CTEABr, a 25oC, foram estudados através de medidas de constantes de velocidade para a reação de b-naftalenossulfonato de metila com íon brometo, sendo que a constante de velocidade diminui com a adição de BuOH. Os dados cinéticos podem ser explicados considerando que: i) a concentração de contra-íons reativos na superfície micelar não é constante, ou seja muda com a adição de BuOH e/ou NaBr; ii) a constante de ligação do substrato à micela depende da BuOH; iii) existe uma constante de velocidade para a decomposição espontânea do substrato e iv) a constante de ligação do BuOH à micela é descrita através de uma constante de distribuição de valor K = 1M-1. Feitas essas considerações, foram calculados valores de km = 9,1 x 10-4 de distribuição para o CTABr e km = 13,8 x 10-4 s-1 para o CTERABr, os quais ajustam perfeitamente os dados experimentais.

APA, Harvard, Vancouver, ISO, and other styles

17

Ferreira, Ligia Catarina Mello. "Efeito da concentração de hidroxido e de sais em reações de eliminação catalisadas por hidroxido de hexadeciltrimetilamonio." reponame:Repositório Institucional da UFSC, 1990. http://repositorio.ufsc.br/xmlui/handle/123456789/75699.

Full text

Abstract:

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e Matematicas Made available in DSpace on 2012-10-16T03:36:21Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T16:43:16Z : No. of bitstreams: 1 79080.pdf: 1954712 bytes, checksum: c7bf826101cd72829d88167ddb5a2703 (MD5) Estudou-se a desidrocloração do 1,1-difenil-2,2,2-tricloroetano (DDTH) em meio básico, em micelas de hidróxilo de cetiltrimetilamônio (CTAOH). Na ausência de KOH adicionando, o comportamento cinético foi o esperado para reações onde o contra íon é o íon reativo. As equações utilizadas levaram a um valor de k2m = 6,5 x 10-4 M-1 s-1, corrigindo previamente as atividades dos íons hidróxidos na fase micelar e calculando a ligação de hidróxido através de uma isoterma de Langmuir. Nas reações de hidrólise do DDTH a concentração constante de CTAOH, variando-se a concentração de hidróxido adicionando, obtivemos valores de k2m = (6,50 +/- 0,30) x 10-4 M-1 s-1, usando kOH = 30 +/- 5 M-1 s-1 é considerando, ainda, as atividades dos íons hidróxidos na fase micelar. No estudo do efeito da adição de sais, na presença de KOH 1,0 M, o modelo da pseudofase troca iônica foi utilizado para ajustar os dados cinéticos, sendo que as concentrações de k2m na faixa de 6,50 x 10-4 M-1 s-1 a 6,80 x 10-4 M-1 s-1 foram obtidos. As constantes de troca iônica (KOH/X) obtidas para os íons X = Cl-, Br-, NO3-, F- e CH3COO- foram de 0,100; 0,050; 0,043; 1,020 e 0,425, respectivamente.

APA, Harvard, Vancouver, ISO, and other styles

18

Frescura, Vera Lucia Azzolin. "Estudo da reação de hidrolise de esteres arilicos e anidrido benzoico em presença de dodecanoato de sodio e sulfobetainas." reponame:Repositório Institucional da UFSC, 1995. http://repositorio.ufsc.br/xmlui/handle/123456789/76300.

Full text

Abstract:

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e Matematicas Made available in DSpace on 2012-10-16T09:05:05Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T20:12:42Z : No. of bitstreams: 1 101779.pdf: 3030271 bytes, checksum: e9894b9e896d22884232cc14aaa6215f (MD5) Determinação dos valores de concentração micelar crítica, grau de ionização micelar, e de pH aparente para misturas binárias de dodecanoato de sódio (SDOD) e sulfobetaínas, SB3-n, para a série com n = 10, 12, 14, 16. Estudo da hidrólise básica do acetato de 2,4-dinitrofenilal (DNPA), octanoato de 2,4-dinitrofenila (DNPO) e do anidrido benzóico (Bz2O) em presença das misturas binárias dos surfactantes. Os sistemas mostraram sinergismo na formação da micela mista. Através da teoria da solução não ideal, foram determinados valores para os parâmetros de interação molecular de b = -2,4, b = -3,4 e b= -4,5, para as misturas de SDOD + SB3-10, SDOD + SB3-12 e SDOD + SB314, respectivamente. As sulfobetaínas são moderados inibidores da hidrólise desses compostos. Enquanto, as misturas de SDOD e SB3-n são catalisadores mais eficientes do que o SDOD. As constantes de velocidade de primeira ordem passam através de um máximo em uma fração molar de SDOD de cerca de 0,5 para o DNPA e DNPO e de 0,8 para o Bz2O. Esses máximos na velocidade são ajustados quantitativamente para a reação do OH e do íon dodecanoato postulando-se que as micelas de suliobetaínas aumentam a nucleofilicidade do íon carboxilato através de um decréscimo na hidratação deste, devido a formação de um par iônico nas micelas mistas.

APA, Harvard, Vancouver, ISO, and other styles

19

Attwood, D. "Metal ion catalysed ester hydrolysis in reverse micelles." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234927.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Bartels, Carl. "Coronae of block copolymer micelles as supports for organometallic catalysis." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82827.

Full text

Abstract:

This thesis presents the results of several studies, the overall goal of which was the design and understanding of a block copolymer micelle in which the coronal chains act as a catalyst support for organometallic species. A model system consisting of reverse micelles of polystyrene-block -poly (sodium acrylate), PS-b-PANa, with coronal chain composed of ca. 210 styrene repeat units and a core radius of ca. 3.0 nm was used in the first study. The coronal chains were loaded to varying extents with Cr(CO)3 fragments in an effort to observe the effect of loading on the corona. The hydrodynamic radii, Rh, were measured by dynamic light scattering, DLS, and compared to a similarly treated sample of PS homopolymer. An increase in Rh by a factor of 3.4 was observed in the micelles, compared to only 1.5 in the homopolymer. A new block copolymer aggregate consisting of Poly (4-bromostyrene)-block-poly(4-vinylphenol), PBS- b-P4VPOH, in which the P4VPOH block could be used to crosslink the core, was developed for use as a coronal support for catalytically active organometallic species. bis-dimethylaminodimethylsilane was used to generate a crosslinked network of siloxane linkages within the core, resulting in a stable micelle. KPPh2 was then reacted with the PBS corona of the micelle to convert the bromostyrene units to analogues of triphenylphosphine. These micelles were then successfully loaded with a rhodium based catalyst. Catalytic activity was tested using the hydrogenation of 1-decene as a model reaction, in which turn-over frequencies of ca. 130 were achieved. The expansion seen in the first study also prompted an effort to develop a theoretical model of coronal chain behavior. A combined hypernetted-chain, mean spherical, Monte-Carlo method was used to model the corona of a micelle. The potential governing the interactions between repeat units was modified to include the effect of having several different species present along the chains. Th

APA, Harvard, Vancouver, ISO, and other styles

21

Assih, Sama Pyahalo. "Polymérisation de micelles ioniques ; effet sur la solubilisation de cétones aromatiques ; effet sur la catalyse de l'hydrolyse baso-catalysée d'esters de paranitrophényle et de l'hydrolyse acido-catalysée de diéthylacétals de benzaldéhydes substitués." Montpellier 2, 1990. http://www.theses.fr/1990MON20277.

Full text

Abstract:

L'etude de la solubilisation de composes hydrophobes et celle des reactions d'hydrolyse acido-catalysee de diethylacetals de benzaldehydes substitues en presence des micelles directes polymerisees ou non polymerisees analogues, a permis de preciser les consequences d'une polymerisation sur les proprietes micellaires. Dans tous les cas, la polymerisation amplifie les effets micellaires. On observe une plus grande solubilisation et des effets catalytiques plus importants. De plus, ces effets apparaissent avec des micelles polymerisees des les plus faibles concentrations, tandis qu'avec les micelles non polymerisees ils ne sont observes qu'au-dessus de la c. M. C. . Ce resultat indique que la polymerisation favorise les interactions micelle/substrat

APA, Harvard, Vancouver, ISO, and other styles

22

Eychenne, Patricia. "Catalyse micellaire en présence de sels métalliques : hydrolyse, oxydation et polymérisation." Toulouse 3, 1994. http://www.theses.fr/1994TOU30141.

Full text

Abstract:

Dans nos travaux la catalyse micellaire par des sels metalliques a ete etudiee sur les hydolyses, les oxydations et les polymerisations. La premiere partie est une mise au point bibliographique: la definition, les proprietes et les avantages des systemes micellaires, emulsions et microemulsions en milieu aqueux et non aqueux sont enonces. La seconde partie concerne la decontamination du paraoxon par la reaction modele d'hydrolyse basique du p-nitrophenyl diphenylphosphate. Le chlorure de cetyl pyridinium est choisi en raison d'une meilleure affinite avec le substrat aromatique. Des etudes en milieu micellaire mixte montrent clairement l'avantage de travailler dans des binaires glycerol/eau plutot que dans l'eau seule. De plus il apparait que le carbonate de potassium joue un role important sur la structure du milieu. La troisieme partie porte sur les reactions d'oxydation du tetrahydrothiophene afin de simuler la destruction d'un toxique particulierement dangereux: l'yperite. Le monoperoxyphtalate de magnesium, plus stable et moins toxique que les oxydants classiques, constitue l'agent d'oxydation de choix. Les systemes micellaires mixtes glycerol/eau presentent egalement un avantage ; les vitesses des reactions plus rapides, les rendements plus eleves avec une proportion plus faible en sulfone sont en faveur d'un meilleur systeme decontaminant. . .

APA, Harvard, Vancouver, ISO, and other styles

23

Duangchan, Apinya. "Residue upgrading using dispersed catalysts prepared in reverse micelles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq27133.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Dennis, Kim Jason. "Use of isomerizable N-alkylmerocyanine dyes to robe molecular interactions within micellar solubilization sites." Scholarly Commons, 1986. https://scholarlycommons.pacific.edu/uop_etds/2116.

Full text

Abstract:

Effects of aqueous surfactant solutions upon cis/trans isomerization reactions of various N-alkyl-merocyanine dyes (II) were studied. Dramatic rate enhancements were found for all dyes in CTAB and SDS solutions above the CMC. CTAB solutions showed the greatest effect with some dye isomerizations catalyzed in excess of 1000-fold. Increases in either CTAB concentration or dye isomerization rates. N-methyl through N-pentyl dye isomerization rates were measured as a function of CTAB concentration and the data treated according to the pseudophase model for micellar catalysis. KS values ranged from 198 to 2000 M-1 for N-methyl to N-pentyl dyes, respectively. Micellar rate constants also increased as dye hydrophobicity was increased. Thermodynamic activation parameters were determined for N-methyl through N-hexylmerocyanine dyes in CTAB solutions. Rate enhancements in CTAB (above the CMC) relative to those in purely aqueous solutions were shown to be due to a substantial lowering of ΔH‡, for the various dyes. Increased CTAB concentrations of N-methyl dye solutions gave reaction rate increases resulting from a lowering of ΔS‡. In 0.054 M CTAB, increases in reaction rates with increased N-alkyl chain length were due to large increases ΔS‡ (from ca. 0 eu for N-methyl to 13 eu for N-hexyl). The data were discussed in terms of molecular interactions which can occur within the micellar solubilization sites.

APA, Harvard, Vancouver, ISO, and other styles

25

Chuenchom, Laemthong [Verfasser]. "Micelle-templated carbon coatings and their applications for catalysis / Laemthong Chuenchom." Gießen : Universitätsbibliothek, 2013. http://d-nb.info/1065395353/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Barnes, Jeffery G. "Elaboration of micelle formation in aqueous and two phase solutions by surface active phosphines." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06112009-063728/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Manfredi, Alex Molina. "Reações de transferência do grupo fosforila catalisadas por oximas e íons cu2+ em meio micelar." Florianópolis, SC, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/96452.

Full text

Abstract:

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-graduação em Química Made available in DSpace on 2012-10-26T12:13:27Z (GMT). No. of bitstreams: 1 301797.pdf: 1816586 bytes, checksum: 0339e22f98c5055c0b07a74c91e84d31 (MD5) Na intenção de se construir modelos bio-inspirados baseados nas características de fosfoesterases, o presente trabalho relata o desenvolvimento de novos modelos teóricos com o intuito de explicar a eficiência catalítica de oximas e de íons Cu2+ nas reações de ésteres de fosfato, principalmente devido à sua importância em sistemas biológicos e também na degradação de compostos organofosforados tóxicos. Nesse sentido, as oximas mostraram ser nucleófilos muito eficientes na reação com o diéster bis(2,4-dinitrofenil) fosfato (BDNPP) quando realizada em meio micelar catiônico (CTABr). Essa reação foi descrita com êxito utilizando-se o modelo de pseudo-fase e troca iônica, e permitiu o ajuste eficiente dos dados experimentais. Tendo em vista a reação de hidrólise espontânea do BDNPP em pH 10, onde o tempo de reação pode chegar a 40 dias, observou-se que a reação é acelerada significativamente e ocorreu em apenas 9 minutos. Avaliou-se também a reação de hidrólise do triéster tris-2-piridil fosfato (2-TPP), na presença de diferentes íons metálicos divalentes, sendo que a reação realizada em meio micelar aniônico (SDS),promoveu um efeito catalítico de até 6400 vezes na presença de íons Cu2+, quando comparado com a reação feita em água. Salienta-se que a reação de hidrólise do tris-3-piridil fosfato (3-TPP) apresentou um efeito catalítico muito inferior ao observado para o isômero 2-TPP, em relação às reações realizadas em água pura. Este resultado indicou que a posição do átomo de nitrogênio no anel aromático possui um papel fundamental como centro de coordenação para os íons Cu2+ no estado de transição. In order to build bio-inspired models based on characteristics of phosphoesterases, the present work reports the development of some new theoretical models in order to explain the catalytic efficiency of oximes and metal ions in the hydrolysis reactions of phosphate esters, mainly due to its importance in biological systems and also in the degradation of toxic organophosphorus compounds. Thus, oximes proved to be very efficient nucleophiles in hydrolysis reaction with the diester bis (2,4-dinitrophenyl) phosphate (BDNPP) when realized in a cationic micellar medium (CTABr). This reaction was successfully described using the pseudo-phase ion exchange model, which allowed to fit the experimental data efficiently. Considering the spontaneous hydrolysis reaction of BDNPP at pH 10, where the reaction time can reach 40 days, the reaction was accelerated significantly and occurred in stunning 9 minutes. In addition, the hydrolysis reaction of the triester tris-2-pyridyl phosphate (2-TPP) was evaluated in the presence of different divalent metal ions, and when an anionic micellar medium (SDS) was used, a catalytic effect up to 6400 times in the presence of Cu2+ ions was observed when compared with the same reaction in water. The hydrolysis reaction of the tris-3-pyridyl phosphate (3-TPP) showed a much lower catalytic effect than that observed for the isomer 2-TPP, for the reactions in pure water. These results indicated that the position of the nitrogen atom in the aromatic ring had a key role as a coordinating center for the Cu2+ ions in the transition state.

APA, Harvard, Vancouver, ISO, and other styles

28

Rubio, Danil Agar Rocha. "Efeitos estruturais e cataliticos sobre micelas de dodecilsulfato de sodio, por adição de n-butonol." reponame:Repositório Institucional da UFSC, 1994. http://repositorio.ufsc.br/xmlui/handle/123456789/76152.

Full text

Abstract:

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e Matematicas Made available in DSpace on 2012-10-16T07:46:54Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T18:44:38Z : No. of bitstreams: 1 98249.pdf: 2005254 bytes, checksum: 4e478fe65deacf2094440262c87aebc2 (MD5) O estudo das propriedades das micelas do dodecilsulfato de sódio por adição de n-butanol mostra que a concentração micelar crítica inicialmente diminui com o aumento da concentração do álcool. O número de agregação micelar e associação micelar também decrescem. As constantes de velocidade observadas em presença de micelas, para a hidrólise ácida dos ésteres de oxima, acetato e octanoato de p-metoxibenzaldoxima decrescem com a adição de n-butanol. O modelo de pseudofase e troca iônica, quando modificado, ajusta os dados cinéticos obtidos em presença de n-butanol. O modelo de pseudofase modificado leva em conta a variação do grau de associação micelar, a permeação dos íons H+ da fase aquosa para a fase micelar e um fator de correção para a diluição dessa fase, devido à presença de álcool.

APA, Harvard, Vancouver, ISO, and other styles

29

HADDAD-FAHED, OMAIMA. "Catalyse micellaire de reactions de substitution nucleophile aromatique comportant des reactifs electriquement charges." Paris 6, 1987. http://www.theses.fr/1987PA066419.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Haddad, Omaima. "Catalyse micellaire de réactions de substitution nucléophile aromatique comportant des réactifs électriquement chargés." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37606110d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Lacanau, Valentin. "Conception et étude physico-chimique d’amphiphiles auto-assemblés pour l’extraction de métaux et la catalyse en milieu aqueux." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS127.

Full text

Abstract:

Ce projet vise à étudier et développer un principe novateur pour la valorisation de métaux issus du recyclage, en particulier du Pd, consistant en l’utilisation directe d’une phase organique issue d’une extraction liquide-liquide pour effectuer des réactions organo-catalysées en phase micellaire aqueuse. Le passage du Pd de la phase organique à la phase aqueuse est assuré par des tensio-actifs (TA) développés par l’équipe CBSA de l’IBMM (C. Pépin & F. Bonneté), et dont la structure vise à être optimisée afin de répondre aux contraintes liées à la récupération par voie hydrométallurgique du Pd issu de déchets électroniques, assurée par l’équipe LHYS de l’ICSM (D. Bourgeois). Suite à une preuve de concept récemment acquise en partenariat entre ces deux équipes du LabexCheMISyst et une équipe de Strasbourg (UdS, F. Bihel), il s’agit ici d’établir de façon rationnelle une relation entre la structure des TA, modulable à façon, les propriétés physico-chimiques des assemblages résultant de leur auto-association, et leur aptitude à contre-extraire puis stabiliser le Pd en phase aqueuse. Les connaissances fondamentales ainsi acquises permettraient alors une valorisation efficace de ces systèmes This project aims to study and develop a novel principle dedicated to the valorisation of recycled metals, especially palladium. It consists in the direct use of an organic phase arising from a solvent extraction process into organo-catalyzed cross-couplings performed in aqueous micellar phases. The palladium transposition from the organic phase into the aqueous phase is performed thaks to surfactants developed by the CBSA team (C. Pépin & F. Bonneté, IBMM), and which structure has to be optimized to answer to the specifications linked with the hyrometallurgical processes dedicated to palladium recovery from electronic wastes, performed by the LHYS team (D. Bourgeois, ICSM). Following a recent proof of concept involving these both teams from the ChemiSyst LabEx and a third team from the Strasbourg University (F. Bihel), the present project will consist in the rational description of the relationship between the surfactants, easily tunable, the physic-chemical properties resulting from their auto-assembly, and their aptitude to back-extract and stabilize the palladium in the aqueous medium. The fundamental knowledge thus acquired will enable and efficient valorization of the proposed systems

APA, Harvard, Vancouver, ISO, and other styles

32

Othman, Mazin A. "Palladium-catalysed aerobic oxidative homocoupling reaction of arylboronic acids in aqueous micellar medium : kinetic and mechanistic studies." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/55140/.

Full text

Abstract:

This thesis is divided into five Chapters. The first Chapter introduces water and micellar solutions as reaction medium, catalysis, palladium catalysts, the Suzuki cross-coupling and the oxidative homocoupling of arylboronic acids. The second Chapter describes studies of the aerobic oxidative homocoupling reaction of arylboronic acids in aqueous micellar media using Pd(bimsulfide)Cl 2 as a (pre) catalyst. Our results, in particular a bell-shaped pH-rate profile, favour a reaction mechanism where the rate-determining step is transmetalation involving a palladium-hydroxo complex and the acidic form of the arylboronic acid, although an alternative mechanism involving a palladium- aqua complex reacting with the arylboronate cannot be excluded. The third Chapter presents the synthesis of Pd-CTAB nanoparticles and their use as catalysts for the aerobic oxidative homocoupling of phenylboronic acid in aqueous micellar solutions. Again, a bell-shaped pH dependence of observed rate constant (&0bs) was observed which, together with our other results, suggests that the reaction again involves pH-dependent Pd-hydroxo and Pd-aqua species. We cannot confirm whether catalysis occurs on the surface of the nanoparticles or through leached Pd atoms/ions. The fourth Chapter embraces bimetallic core-shell Au-Pd nanoparticles encapsulated in a shell of poly(7V-isopropylacrylamide) (pNIPAM) of different sizes and morphologies, as well as Pd-pNIPAM nanocomposites. Both systems were used to catalyse the aerobic oxidative homocoupling reaction of PBA in aqueous micellar medium. Our kinetic studies gave similar results as observed for the Pd-complex described in Chapter 2 and the nanoparticles described in Chapter 3. Hence, an analogous mechanism was proposed. The observed rate constant showed non-Eyring-like behaviour, highlighting the dependence of Abs on the state (swollen or collapsed) of the pNIPAM shell surrounding the nanoparticles. Finally, the fifth Chapter describes preliminary studies exploring aerobic oxidative cross-coupling reactions of arylboronic acids and their derivatives in aqueous micellar solutions. Conclusions, future outlooks, remarks and suggestions finish Chapter 5 and the thesis.

APA, Harvard, Vancouver, ISO, and other styles

33

Bouilhac, Cécile. "Nouvelle approche en catalyse supportée de polymérisation de l'éthylène : conception de supports organiques originaux." Bordeaux 1, 2007. http://www.theses.fr/2007BOR13482.

Full text

Abstract:

Les travaux décrits dans ce manuscrit ont trait à l’élaboration de nouveaux supports organiques pour la catalyse de polymérisation de l’éthylène. Dans une première approche, des étoiles de polystyrène portant à l’extrémité de chaque branche, des fonctions capables d’immobiliser ou de générer in situ des activateurs aluminiques de catalyseurs métallocènes et post-métallocènes ont été synthétisées par polymérisation radicalaire contrôlée (ATRP). La seconde approche est basée sur la micellisation de (co)polymères fonctionnels en solution et utilise ces structures micellaires comme nanoréacteurs pour encapsuler le système catalytique. Testés en polymérisation de l’éthylène en présence d’un catalyseur à base de fer (MeDIP(2,6-iPrPh2)FeCl2), ces différents supports activés produisent, avec une activité catalytique élevée, des billes de polyéthylène de morphologie contrôlée Functionalized organic supports have been developed for the heterogenization of single-site catalysts towards ethylene polymerization. A first approach consists in the synthesis of star-like PS composed of a microgel core and PS arms end-capped by various functions. These latter can either immobilize or generate in-situ aluminic activators of metallocenes and late transition metal complexes. A second strategy is based on the self-assembly of functional (co)polymers in solution. The so-formed micellar structures are capable of embedding the catalytic system and can serve as nanoreactors for the production of polyethylene beads. Tested in ethylene polymerization in the presence of iron-based complexes (MeDIP(2,6-iPrPh2)FeCl2), these different systems enable the production, with a high catalytic activity, of well-defined polyethylene beads

APA, Harvard, Vancouver, ISO, and other styles

34

Souza, Franciane Dutra de. "Efeito da adição de sais nas propriedades físico-químicas de micelas normais e reversas formadas por surfactantes dipolares iônicos." Florianópolis, SC, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/99224.

Full text

Abstract:

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química Made available in DSpace on 2013-03-04T17:54:32Z (GMT). No. of bitstreams: 1 301318.pdf: 1961320 bytes, checksum: db9fc3bdf31d72497d8746a4360a124f (MD5) Neste trabalho, estudaram-se as interações de cátions com micelas normais de sulfobetaína. A variação do potencial zeta mostrou que a incorporação de cátions pelas micelas é dependente da valência e tamanho das espécies positivas: cátions trivalentes interagem melhor que di- e monovalentes. Também se observou que a valência e o tamanho dos cátions di- e monovalentes influenciam o raio hidrodinâmico da micela, com o primeiro exercendo maior efeito sobre o raio que o último. Também foram estudadas as propriedades de micelas reversas de um surfactante dipolar iônico contendo um anel imidazólio (ImS3-14). Os resultados mostraram que este surfactante forma micelas reversas em clorofórmio somente na presença de soluções salinas de NaClO4 e NaCl. O anion perclorato que é mais volumoso e menos hidratado que o cloreto interage mais fortemente com a interface aumentando a solubilidade da água em micelas reversas. Cálculos computacionais indicaram a presença de interações entre o anion sulfonato e os hidrogênios aromáticos do surfactante em clorofórmio. O deslocamento dos sinais de RMN 1H da água e dos hidrogênios aromáticos depende da quantidade de água presente (w0) nas micelas reversas. Também foi observado que a variação do w0 altera significativamente o espectro de absorção da água no infravermelho. Reações de hidrólise básica de um diéster de fosfato em micelas reversas foram mais rápidas na presença de perclorato do que de cloreto. Isto é consistente com a observação de que o perclorato aumenta a solubilidade da água nestes sistemas. As micelas reversas de ImS3-14 foram capazes de estabilizar as nanopartículas de paládio mas não se mostraram capazes de estabilizar as de ouro. In this work interactions between cations and sulfobetaine micelles were studied. Variation of zeta potential showed that incorporation of cations by sulfobetaine micelles is dependent on the valence and size of the positive species: trivalent cations interact with micellar interface better than di- and monovalent cations. We also observed that valence and size of di- and monocations influence the hydrodynamic radius of the micelle, with the former contributing to a greater size of the radius than the latter. We also studied the properties of reversed micelles from a surfactant containing a dipolar ionic imidazolium ring (ImS3-14). Results showed that this surfactant forms reversed micelles in chloroform only in presence of aqueous solutions of NaClO4 and NaCl. Perchlorate anion which is greater in shape and less hydrated than chloride interacts more strongly with micellar interface increasing water solubility in reversed micelles. Computational calculations indicate the presence of interaction between sulfonate anion and the acidic aromatic hydrogen of the surfactant in chloroform. 1H NMR chemical shifts of water and aromatic hydrogens depend on the amount of water (w0) incorporated in the reversed micelle. It was also observed that varying w0 changes significantly the water absorption infrared spectrum. Alkaline hydrolysis reactions of a phosphate diester in reversed micelles were more accelerated in the presence of perchlorate than chloride. This is consistent with the previous observation that perchlorate increases water solubility in such systems. Reversed micelles of ImS3-14 in chloroform were capable of stabilizing palladium nanoparticles but not gold nanoparticles.

APA, Harvard, Vancouver, ISO, and other styles

35

Hicks, Tanya Temaca. "Preparation, Characterization, and Activity of Mono-Dispersed Supported Catalysts." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4765.

Full text

Abstract:

Mono-dispersed supported Ni catalysts were synthesized using the water-CTAB-hexanol reverse micellar system. The core of the reverse micelles contained an aqueous solution of NiCl2. Dynamic light scattering measurements showed that microemulsions having a water-to-surfactant molar ratio, Wo, of 10 lead to reverse micelles with lowest polydispersity, longest stability, and size range of interest. At an oil-to-aqueous phase ratio of 2, the diameter of the reverse micelles was found to increase with Wo in a linear fashion. At higher values of Wo (i.e. 25-30), the polydispersity was found to increase when lowering the amount of surfactant in the system. Ultimately, O/A = 2 and Wo = 10 were chosen as optimal conditions for microemulsion preparation. The aqueous NiCl2 concentration within the micelles was varied between 0.1 and 0.001 M. DLS results showed that although the average micelle diameter was between 70-83 nm throughout the range of metal salt concentrations, the crystallite size estimate based upon the reported micelle diameter and known aqueous NiCl2 concentration ranged between 2 to 7 nm. Therefore, the Ni crystallite size was varied by changing the aqueous NiCl2 concentration due to instability issues arising when changing the value of Wo. After deposition onto an alumina mesh support, the particles were dried, calcined, and reduced to produce Ni clusters. SEM and EDS analysis was used to confirm the presence of Ni compounds after the calcination stage. By the varying the aqueous NiCl2 concentration within the micelles, .0039, .0013, and .00039 wt. % Ni catalysts were produced and characterized using SEM. Particles in the size range of 10-14 nm were noticed for the .0039 wt. % Ni catalysts after reduction, 7-11 nm for .0013 wt. % Ni, and 5-9 nm for .00039 wt. % Ni. The lower-end of these particle size ranges was comparable to the crystallite size estimates. Ethane hydrogenolysis and ethylene hydrogenation reactions were conducted over the emulsion-prepared catalysts in order to determine particle size effects on catalytic activity. Results showed that the catalytic activity, defined in terms of per unit metal surface atom (or TON, turnover number), decreases with increasing particle size for the hydrogenolysis reaction. This trend may be due to an intrinsic size effect in which smaller particles exhibit the chemical or structural properties necessary for achieving a higher reaction rate. The results for ethylene hydrogenation showed that the reaction rate did not significantly change with crystallite size, confirming that the reaction is facile or structure-insensitive.

APA, Harvard, Vancouver, ISO, and other styles

36

Hu, Ping. "Design of oxidation-sensitive polymer micelles for inflammation targeting." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/design-of-oxidationsensitive-polymer-micelles-for-inflammation-targeting(8ec02724-aeef-4ce8-ac2d-a3186de6267e).html.

Full text

Abstract:

The research presented in this thesis focuses on the molecular design of an oxidation-sensitive nanocarrier and its enzyme conjugate with a view of their application in the field of biomaterials. I have polarised our attention on a specific class of polymers, the polysulfides, for their environmental responsiveness (towards oxidising substances, a condition often associated with inflammatory reactions), interesting physico-chemical properties, ease of the preparation and multiple possibilities for further modifications and bioconjugations, which are perfectly suitable for the development as systems for drug delivery applications. In this work we firstly have focused on the synthesis of amphiphilic poly(propylene sulfide)-poly(ethylene glycol) (PPS-PEG) block copolymers by employing vinyl sulfone as the functional group to link the blocks and modify the end of the PEG. This study was followed by an investigation of the macromolecular interchange and payload exchange of the formed polymeric micelles to understand the 'co-formulation' events, employing fluorophores (dansyl groups) and quenchers (dabsyl groups) either as terminal groups in macroamphiphiles or as encapsulated hydrophobic payloads. In another part of the work, I have developed a micellar system with which simultaneously to two of the most important ROS: superoxide and hydrogen peroxide, for inflammation-responsive drug release. The system is composed of superoxide dismutase (SOD) conjugated to oxidation-sensitive amphiphilic polysulfide/PEG block copolymers; the conjugate combines the SOD reactivity towards superoxide with that of hydrophobic thioethers towards hydrogen peroxide. Specifically, here we have demonstrated how this hybrid system can efficiently convert superoxide into hydrogen peroxide, which is then 'mopped-up' by the polysulfides. This mode of operation is functionally analogous to the SOD/catalase combination, with the advantage of being based on a single and more stable system.

APA, Harvard, Vancouver, ISO, and other styles

37

Faria, Athos Cabeda. "Estudo comparativo entre catalise por micelas e polimeros em reações de hidrolise alcalina." reponame:Repositório Institucional da UFSC, 1994. http://repositorio.ufsc.br/xmlui/handle/123456789/76157.

Full text

Abstract:

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e Matematicas Made available in DSpace on 2012-10-16T07:49:36Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T18:43:52Z : No. of bitstreams: 1 98253.pdf: 1369320 bytes, checksum: 12e5b1b1341edc77ee1479aa1a95db24 (MD5) O presente trabalho apresenta a preparação de dois polímeros do tipo ioneno e um estudo cinético comparativo da hidrólise do anidrido benzóico (pHs 9,00 e 8,50) e benzoato de p-nitrofenila (pH 10,00) através de espectrospcopia UV. A hidrólise catalítica do anidrido benzóico em meio básico foi estudada em condição de primeira ordem na presença dos surfactantes brometo de hexadeciltrimetilamônio (HTAB), cloreto de benzildimetilhexadecilamônio (BDHAC) e dos polímeros catiônicos cloreto de 2-hidróxi-3-ioneno e poli [(dipropilimínio) - 1,3-brometo de propandiila] (33R33). A hidrólise do éster foi estudada somente na presença do cloreto de 2-hidróxi-3-ioneno. A síntese do cloreto de 2-hidróxi-3-ioneno produziu bons rendimentos (90%) e um produto de coloração branco-amarelada, enquanto a síntese de 33R33, que é nova na literatura, apresentou baixo rendimento e um produto de cor amarela-alaranjada. Ambos polímeros são altamente higroscópicos e foram caracterizados por técnicas de IV, RMN e DSC. O polímero catiônico cloreto de 2-hidróxi-3-ioneno provou ser o mais eficiente catalisador e um mecanismo detalhado é proposto para a reação com anidrido benzóico, baseado nas evidências cinéticas obtidas. Em ordem decrescente de eficiência catalítica seguem BDHAC>33R33>HTAB (em termos de kobs). Os dados cinéticos obtidos foram tratados com o modelo de pseudofase troca iônica no caso dos surfactantes, mostrando uma boa concordância. no caso dos polímeros do tipo ioneno foi utilizada uma equação de Michaelis-Menten modificada para tratamento dos dados.

APA, Harvard, Vancouver, ISO, and other styles

38

KESSOUM, M. ABDELKRIM. "Contribution a l'etude de la catalyse micellaire sur les reactions d'additions nucleophile aromatique complexes de yaovsky." Paris 6, 1992. http://www.theses.fr/1992PA066662.

Full text

Abstract:

Dans le cadre de l'effet des milieux micellaires sur les reactions d'addition nucleophile, nous avons etudie cinetiquement les formations et les decompositions de quelques complexes de meisenheimer et de janovsky en milieu micellaire. En raison des effets d'extraction et des transferts d'especes chargees entre les deux phases micelle et solution nous avons pu realiser pour la premiere fois l'etude cinetique et thermodynamique de quelques reactions de janovsky du 1,3,5-trinitrobenzene et du 1,3-dinitronaphtalene dans un tel milieu. Soulignons que dans l'eau pure les complexes carbones du tnb et du 1,3-dinitronaphtalene n'ont pu etre etudies, probablement pour des raisons de solubilite ou de stabilite. Nous avons ainsi constate que la vitesse de formation de complexes d'addition nucleophile augmente en presence de micelles cationiques alors que leur vitesse de decomposition diminue, ce qui explique clairement le caractere primordial joue par la presence des micelles cationiques, sur la stabilite de ce type de complexes. D'autre part, nous avons montre que l'influence de l'addition d'un sel sur les vitesses de reaction n'est pas uniquement de nature electrostatique puisqu'elle depend fortement de la nature de celui-ci. L'introduction d'un sel dans des solutions micellaires ioniques provoque en fait deux reactions complementaires qui sont d'une part, l'evolution de la difference de potentiel entre la phase micellaire (phase dispersee) et la phase aqueuse (phase continue) et d'autre part, un reequilibrage purement chimique des especes entre les deux phases chargees. Cinetiquement, l'addition de sel en presence de micelles cationiques entraine un ralentissement de la reaction tandis qu'en presence de micelles anioniques, on remarque au contraire une acceleration. L'importance de cette variation depend de la nature du sel utilise

APA, Harvard, Vancouver, ISO, and other styles

39

Hicks, Tanya Temaca. "Preparation, characterization, and activity of mono-dispersed supported catalylsts [sic]." Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-07212004-102914/unrestricted/hicks%5Ftanya%5Ft%5F200412%5Fms.pdf.

Full text

Abstract:

Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2005. Agrawal, Pradeep K., Committee Chair ; Bommarius, Andreas S., Committee Member ; Schork, F. Joseph, Committee Member. Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

40

Jallet, Vincent. "Conception de polyoxométallates amphiphiles pour la catalyse d'oxydation en microémulsion." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066275/document.

Full text

Abstract:

L'avenir de l'industrie chimique réside dans le développement de nouvelles méthodes de synthèse, et notamment dans la mise en place de réactions catalytiques et l'utilisation de milieux réactionnels performants. Ainsi, le but de ce travail de recherche doctorale était de développer des tensioactifs catalytiques à base de polyoxométallates pour effectuer des réactions de catalyse d'oxydation de substrats organiques en microémulsion. Ce travail de recherche a débuté par la synthèse et la caractérisation de nouvelles familles de tensioactifs à base de polyoxométallates, et le contrôle de la nature des contre-ions a permis de mettre au point des molécules hydrosolubles. Ces molécules amphiphiles ont été utilisées pour effectuer de la catalyse d'oxydation en phase homogène dans des solvants usuels et "verts". L'étude de la catalyse a permis d'apporter une contribution à la compréhension des sites actifs de la catalyse d'oxydation. L'étude des propriétés d'agrégation de plusieurs de ces familles de polyoxométallates amphiphiles a été menée par des techniques de caractérisation physico-chimique telles que le SAXS et la RMN et a montré la formation de micelles. L'étude de l'hydrolyse des polyoxométallates amphiphiles en solution aqueuse a mis en évidence le rôle primordial du contrôle du pH sur la stabilité des POMs amphiphiles en solution aqueuse. Une microémulsion stabilisée par des polyoxométallates amphiphiles a été décrite pour la première fois et caractérisée par SAXS et par RMN HMQC. La catalyse d'oxydation en microémulsion n'a pas pu être réalisée à cause de l'inhibition et/ou hydrolyse du catalyseur en présence d'eau The future of the chemical industry lies in the development of new synthetic methods, especially in setting up catalytic processes and in using new and efficient media. The aim of this doctoral research was to develop polyoxometalate based catalytic surfactants to catalytically oxidize organic substrates in microemulsions. This research begun with the synthesis and the characterization of new polyoxometalate based surfactant families, and water soluble molecules could be obtained by controlling the nature of the counterions. These amphiphilic molecules were used to make a homogeneous oxidation catalysis in most commonly used organic solvents and so-called green solvents. The study of the catalysis contributed to the understanding of active sites. The study of the aggregation properties of some of our amphiphilic POMs was carried out using physicochemical characterization techniques such as SAXS and NMR, and the formation of micelles was evidenced undoubtedly. One drawback of our system is the slow hydrolysis of the phosphonylated group grafted onto the POM framework in water, which has been showed to be accelerated in acidic conditions. Despite this degradation, we succeeded in stabilising a microemulsion by amphiphilic polyoxometalates for the first time, and we characterized it by SAXS and NMR HMQC. The oxidation catalysis in microemulsion couldn’t be carried out because of the catalyst inhibition and/or hydrolisis in presence of water

APA, Harvard, Vancouver, ISO, and other styles

41

Hoang, Minh Duc. "Conception et synthèse d’auto-assemblages d’amphiphiles diacétyléniques pour les applications en nanomédecine et en catalyse." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS371/document.

Full text

Abstract:

Les travaux décrits dans ce manuscrit portent sur l’étude de nanostructures obtenues par auto-assemblages d’amphiphiles diacétyléniques polymérisables. Essentiellement deux familles de composés ont été étudiées (micelles sphériques et rubans en bicouches) et valorisées, d'une part, pour des applications biomédicales et, d’autre part, pour la catalyse. Dans un premier temps, des micelles cationiques polymérisées assemblées à partir d’amphiphiles diacétyléniques sont synthétisées. Ces micelles ont été valorisées pour la prise en charge et la transfection d’ARN interférents in vitro. Ensuite, un catalyseur micellaire « biocompatible » incorporant du cuivre a été développé pour promouvoir des transformations chimiques in vitro. Nos études ont ainsi porté sur la réaction de cycloaddition 1,3-dipolaire de Huisgen que nous avons mise en œuvre dans le compartiment intracellulaire. Enfin, nous nous intéressons à la synthèse et à la formulation d’amphiphiles diacétyléniques en architectures supramoléculaires qui ont été utilisées pour la catalyse asymétrique et semi-hétérogène de la réaction d'aldolisation The work described in this manuscript focuses on the study of nanostructures obtained by self-assembly of polymerizable diacetylenic amphiphiles. Two families of compounds have been studied (spherical micelles and bilayer ribbons) and used for biomedical applications on the one hand and for catalysis on the other. At first, polymerized cationic micelles assembled from diacetylenic amphiphiles are synthesized. These micelles were valorized for the transfection of small interfering RNAs in vitro. Then a "biocompatible" micellar catalyst incorporating copper was developed to promote in vitro chemical transformations. Our studies focused on the Huisgen 1,3-dipolar cycloaddition that we implemented in the intracellular compartment. Finally, we are interested in the synthesis and formulation of supramolecular architectures from diacetylenic amphiphiles. These systems have been used for the asymmetric and semi-heterogeneous catalysis of the aldol reaction

APA, Harvard, Vancouver, ISO, and other styles

42

Dani, Silvia. "Catalise micelar da decomposicao do p-nitrofenildifenifosfato na presenca de surfatantes com um e dois grupos lipofilicos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 1991. http://hdl.handle.net/10183/26886.

Full text

Abstract:

Os propósitos deste trabalho foram o estudo do processo de agregação em água dos surfatantes brometo de cetildi metiletilamônio, brometo de dilaurildimetilamônio e cloreto de metildodecilbenziltrimetilamônio, como também, do efeito catalítico destes surfatantes na decomposição do éster p-nitrofenildifenilfosfato em meio básico. O éster de fosfato é um inibidor da acetilcolinesterose e é comumente empregado como modelo de gases que atuam sobre o sistema nervoso. O processo de agregação foi estudado principalmente com técnicas de tensiometria. A concentração micelar crítica (CMC) dos surfatantes foi determinada a 25°, 32° e 40°C e os parâmetros de micelização tais como a energia livre padrão de micelização, ΔGºm' a entalpia de micelização, ΔHºm' e a entropia de micelização, ΔSºm' foram calculados. Os surfatantes brometo de cetildimetiletilamônio, brometo de dilaurildimetilamônio e cloreto de metildodecilbenziltrimetil amônio apresentaram, respectivamente, os seguintes valores de CMC, ΔGºm' ΔH°m e ΔS°ma 25°C: 9,05x10 -4 M, -4,14kcal/mol -1,37 kcal/mol, 9,33 u.e.; 4,93x10 -5 M, -5,87 kcal/mol,-1,12 kcal/mol, 16,0 u.e.; 1,12x10 -2 M, -2,66 kcal/mol, -0,820 kcal/mol, 6,17 u.e. O valor mais negativo de 6Gom para obro meto de dilaurildimetilamônio indica que a formação de mice las deste surfatante, com duas caudas, é um processo mais favorável em relação a formação de micelas dos demais surfatantes, com somente uma cadeia hidrofóbica. A hidrólise do p-nitrofenildifenilfosfato (NIDIF) foi estudada principalmente a 15, 25 e 35°C e algumas vezes a 20 e 30°C em soluções aquosas contendo NaOH e micelas dos três tensoativos. Técnicas de espectrofotometria foram usadas para medir as ~onstantes de velocidade de pseudo-primel ra ordem (k~) e de segunda ordem (k 2). Também foram determi nados parâmetros de ativação como a energia de ativação, Ea' a energia livre de ativação, ΔG#, a entalpia de ativação, 6H*, e a entropia de ativação ΔS#: A concentração de NaOH va riou entre 0,0005M e 0,010M. Alguns valores típicos de k~ obtidos a 25°C em soluções 0,005M de NaOH para os surfatantes brometo de cetildimetilamônio, brometo de dilaurildimetilamônio e cloreto de metildodecilbenziltrimetilamônio são os seguintes: 3,60xl0 -2 s -1( 0,6xl0 -3 M) , 5,70xl0 -2 s -1( 1,80 x 10 -3 M) , 4,7x10 -2 s -1 (4,Ox10 -3 M); 7,5x10 -2 s -1 (0,6x10 -3 M) ,8,8 x 10 -2 s -1 (1,Ox10 -3 M) , 5,lx10 -2 s -1( 4,Oxl0 -3 M) ; 3,5xl0 -3 s -1( 0,4 x10 -2 M), 4,7x10 -3 s -1 (1,2,xl0 -2 M), 2,4x10 -3 s -1( 4x10 -3M). Todos os perfis de velocidade apresentaram um máximo em função da concentração de tensoativo, o que é concordante com a catálise micelar de reações bimoleculares. Os fatores catalíticos máximos foram de, aproximadamente, 80 vezes para o surfatante brometo de cetildimetiletilamônio, 120, para o brometo de dilaurildimetilamônio e 60, para o cloreto de me tildodecilbenziltriemtilamônio. A energia livre de ativação e a entropia de ativação em soluções 0,005M de NaOH na ausência de tensoativo foram iguais a 22,33 kcal/mol e - 29,7 u.e., respectivamente. Na presença de tensoativo, a energia livre de ativação diminui de, aproximadamente, 3 kcal/mol en quanto que os valores de entropia de ativação tornam-se mais negativos, em média, de 7 u.e. Os resultados experimentais indicam que micelas dos surfatantes estudados aceleram a de composição do éster de fosfato p-nitrofenildifenilfosfato em meio aquoso e são catalisadores muito bons. Os resultados experimentais foram analisados em termos de modelos atuais de catálise micelar. The purpose of this work was the study of the aggregation process of the surfactants cetyltrimethylammonium bromide (CTAB), dilauryldimethylammonium bromide and methyldodecylbenzyltrimethylammonium chIar ide in water and their catalytic effect on the basic hydrolysis of p-nitrophenyldiphenyl phosphate. This phosphate ester is an acetylcholinesterase inhibitor and is commonly used as a model for nerve gases and pesticides. The aggregation process was studied mainly by surface tension techniques. The criticaI micellar concentration (CMC) of the surfactants was measured at 25°, 32°C and 40°C and thermodynamic parameters such as the standard free energy of micellization, ΔGºm, enthalpy ΔHºm, and entropy of micellization, ΔS°m, were de termi ned. The corresponding values of CMC, ΔGºm, ΔHºm and ΔSºm obtained for the three surfactants were: for cetyldimethylammonium bromide, 9. 05x 1 0-4M, -4.15 kcal/mol, -1.37 kcal/mol, 9.33 eu; for dilauryldimethylammonium bromide, 4.93x10 -5 M, -5.87kcal/ mal, -1.12 kcal/mol, 16.0 eu; and for methyldodecylbenzyltrimethylammonium chloridej 1.12x10 -2 M, -2.66kcal/mol, -0.82 kcal/mol and 6.17 eu, respectively. The more negative value of 6Gom for the twin-tail surfactant dilauryldimethylammonium bromide indicates that the formation of micelles by this surfactant is more favorable than that of the single-tail surfactants. The hydrolysis of p-nitrophenyldiphenyl phosphate (NIDIF) was studied mainly at 15°, 25° and 35°C and at times at 20° and 30°C in aqueous solutions containing NaOH and micelles of the three surfactants. Pseudo first order (ko/) and second order (k 2 ) rate constants were measured using spectrophotometric techniques. Activation parameters such as the activation energy E , the free energy, ΔG#, enthalpy, a ΔH#, and entropy of activation, ΔS#, were also determined. The concentration of NaOH varied from 0.0005M and 0.0100M. Some typical values obtained for ko/ in 0.0050M solutions of NaOH at 25°C at different concentrations of three surfactants were as follows: cetydimethylammonium bromide, 3.60x10-2sec-1 ( 0.60x10 -3 M surfactant), 5.70x10 -2 sec -1( 1.80x10 -3 M) , 4,70 x 10-2sec- 1(4.00X10- 3M); dilauryldimethylammonium bromide, 7.50x10 -2 sec -1( 0.60x10 -3 M) ,8.8x10 -2 sec -1( 1.00x10 -3 M) , 5.10x 10 -2 sec -1 (4.00x10 -3 M) ; and methyldodecylbenzyltrl. methylammnium brom.l de, 3.50x10 -3 sec -1( 0.40x10 -2 M) ,4.70x10 -3 sec -1 ( 1.20x10 -2 M) and 2.50x10 -3 sec -1( 4.00x10 -3 M) , respectively. AlI reaction pro files exhibit a maximum as a function of surfactant concentration, in accordance with previous observations for bimolecular micellar catalyzed reactions. The maximum catalytic factors were approximately 80 times for cetyldimethylammonium bromide, 120 for dilauryldimethYl ammonium bromide and 60 for methyldodecylbenzyltrimethylammonium chloride. The free energy of activations for 0.005M NaOH solutions without surfactant was 22.33 kal/mol and the entropy of activation was -29.7 eu. In the presence of surfactant ΔG* diminished about 3 kal/mol and ΔS* diminished on the average 7 eu for the three surfactants. The experimental results show that micelles of the surfactants studied speed up the decomposition of p-nitrophenyldiphenyl phosphate and are very good catalysts. The experimental results were a1so analyzed in terms of present mode1s for mice1lar cata1ysis.

APA, Harvard, Vancouver, ISO, and other styles

43

Oliveira, Maria Rita Perez de. "Estudo das condições de hidrólise de álcoois primários sulfatados." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-19072011-165944/.

Full text

Abstract:

Álcoois primários sulfatados de cadeia longa, usualmente na forma de sais de sódio, são tensoativos de grande interesse comercial utilizados em diversas formulações de higiene pessoal e limpeza doméstica. Eles são produzidos comercialmente através da reação de álcoois etoxilados com trióxido de enxofre seguida de imediata neutralização com hidróxido de sódio. O produto formado é uma solução neutra de álcool primário etoxilado sulfatado em água. Sabe-se que a armazenagem desse produto por longos períodos de tempo em temperaturas elevadas pode levar à hidrólise completa, mas, em condições normais de uso e temperatura ambiente é esperado que o produto seja resistente à hidrólise. No entanto observou-se que algumas amostras comerciais de lauril éter sulfato de sódio que foram estocadas por diferentes períodos de tempo em frascos fechados à temperatura ambiente sofreram hidrólise em intervalos de tempo relativamente curtos. Isso leva à hipótese de que o comportamento de hidrólise seria influenciado por outras variáveis além da temperatura e do tempo de estocagem. O presente trabalho consistiu em identificar as variáveis de maior impacto na reação de hidrólise por meio de experimentos planejados. O teor de ativos foi acompanhado ao longo da reação para avaliar o efeito da presença de eletrólitos, de material insulfatado, em diferentes temperaturas, variando-se o pH inicial por meio da adição de ácido clorídrico. O comportamento da reação de hidrólise observado foi compatível com aquele descrito na literatura para o dodecil sulfato de sódio. A hidrólise apresentou-se como sendo autocatalítica, com a aceleração da taxa de reação provavelmente causada pela presença de íons hidrogênio liberados na reação. Foi possível identificar que as variáveis de maior efeito na reação foram: pH inicial, o teor de cloreto de sódio e a temperatura. O modelo de troca iônica em pseudo-fase foi utilizado para o tratamento dos resultados experimentais e mostrou-se adequado tendo sido, portanto, utilizado para prever o comportamento de estabilidade do produto à temperatura ambiente e nas condições em que o produto é normalmente comercializado. Um modelo empírico de redes neurais foi desenvolvido com sucesso para prever o comportamento do pH ao longo do tempo para as condições estudadas. Long-chain primary alkyl sulfuric acids, usually as their sodium salts, are important commercial surfactants used in a large number of household and personal care formulations. They are commercially produced by treatment of mixtures of ethoxylated fatty alcohols with sulfur trioxide followed by immediate neutralization with sodium hydroxide, a neutral aqueous mixture of sodium primary alkyl ether sulfate is obtained. It is known that prolonged storage of the material at elevated temperature can lead to complete hydrolysis but under normal use and typical environmental conditions the product is expected to be resistant to hydrolysis. In spite of that it has been observed that some commercial samples of sodium lauryl ether sulfate stored for different periods of time in sealed containers at room temperature have undergone hydrolysis in a relatively short period of time which leads to the hypothesis that the hydrolysis behavior would be strongly influenced by variables other than temperature and storage time. The present work consisted of identifying the process variables with the most significant effect on the acid hydrolysis by using experimental design. The rate of hydrolysis has been followed acidimetrically to evaluate the effect of electrolytes as well as the concentration of unsulfated matter at different temperatures, over a wide initial pH range, under the presence of added hydrochloric acid. The pattern of kinetic behaviour observed was broadly the same as previously described for the sodium dodecyl sulfate. The hydrolysis presented the characteristic autocatalytic form, the catalysis presumably arising from the production of hydrogen sulfate ions. It was possible to observe that the most significant effects on the rate of hydrolysis were the initial pH, the total amount of sodium chloride and the temperature. The results were also discussed in terms of the ion-exchange pseudophase model of the micelle reaction. Accordingly to the fitting of parameters that was carried out it is possible to conclude that the pseudo-phase ion-exchange theory is found to account satisfactorily for the results reported and it was used to predict the stability behavior of the product at room temperature and under normal commercial conditions. A neural network based model was also successfully developed in order to predict the pH behavior in the conditions studied.

APA, Harvard, Vancouver, ISO, and other styles

44

Thamrin. "Synthèses et perspectives d'applications de nouveaux composés oxygènes, thiono-organiques gras et tetrazines grasses d'origine végétale." Toulouse, INPT, 1997. http://www.theses.fr/1997INPT048G.

Full text

Abstract:

Une gamme d'ethers gras satures, monoinsatures, lineaires et ramifies a ete synthetise dans un systeme polyphasique emulsionnant en catalyse micellaire. La phase huile est constituee d'un surfactant (sels d'ammonium quaternaires), d'un co-surfactant (alcool gras) et d'un bromoalcane. Selon la nature de l'alcool gras utilise, les ethers satures ont ete obtenus en un cycle de reaction alors que les ethers gras monoinsatures ont ete prepares en deux cycles. Les ethers obtenus possedent des proprietes lubrifiantes comparables aux esters correspondants (viscosite, indice de viscosite, point d'ecoulement, point eclair. . . ). En outre, ils ont une bonne stabilite thermique (atg - atd). De plus, l'oxyde de 2-ethylhexyle d'oleyle introduit a 5% dans l'huile de colza a permis l'abaissement du point de congelation de -20,7c a -47,8c. L'etherification a aussi ete realisee sur l'huile de fusel, co-produit de la fermentation alcoolique. Nous avons alors obtenus un melange d'ethers qui sont d'excellents modificateur de viscosite. Des esters gras simples et des huiles vegetales (huile de crambe et huile de palme) ont ete ensuite transformes avec des rendements eleves, en nouveaux composes thionoorganiques par echange (c= o c= s au moyen du reactif de lawesson. L'huile de crambe thionee a 6% dans l'huile de crambe (94%) montre des proprietes anti usure et extreme pression. Les thionoesters et thionotriglycerides se sont averes etre des bons intermediaires de la reaction d'acylation de l'hydrate d'hydrazine. On aboutit a des dihydrotetrazines disubstituees grasses par insertion de l'heteroatome n et l'heterocyclisation. Ces derives tetraazoles presentent des proprietes antifongiques. En outre, ils possedent des proprietes antioxydantes qui les predestinent dans les domaines d'anticorrosion.

APA, Harvard, Vancouver, ISO, and other styles

45

Silva, Idélcio Nogueira da. "Distribuição e reatividade de íons em soluções de micelas e vesículas." Universidade de São Paulo, 1995. http://www.teses.usp.br/teses/disponiveis/46/46131/tde-05022016-092756/.

Full text

Abstract:

A extensão relativa da dissociação iônica (α) de micelas de cloreto de hexadecildimetilamônio (CTACI), brometo de hexadecildimetilamônio (CTAB), vesículas de cloreto de dioctacecildimetilamônio (DODAC) e brometo de dioctadecildimetilamônio (DODAB) foram determinadas usando um método de dediazonização. O método de dediazonização consiste na determinação de produtos resultantes da lenta decomposição espontânea de tetrafluorborato de 2,4,6-trimetilbenzenodiazônio, seguida pela reação rápida do cátion fenílico com nucleófilos presentes no meio. Foi demostrado que este método determina a composição relativa da pseudofase aquosa interagregado. Os valores de α obtidos para CTACI e CTAB foram, respectivamente, 0,29 e 0,26, em excelente concordância com valores previamente publicados. O coeficiente de troca iônica para brometo/cloreto, determinado através do mesmo método, foi de 2,65, coincidindo com dados publicados. Estes valores confirmam o uso deste método para se obter tanto grau de dissociação iônica relativo como coeficientes de seletividade. O método foi também aplicado para a determinação do grau de dissociação iônica externo (αe e interno (αi) de vesículas de DODAC e DODAB. Para vesículas de DODAB sonicadas por tip obteve-se αe de 0,20; para vesículas de DODAC sonicadas em banho αe foi 0,20; para vesículas de DODAC sonicadas por tip αe foi 0,25 e para vesículas de DODAC grandes αe foi 0,11. Foi também determinado, pela primeira vez, o valor de 0,07 para o αi de vesículas grandes de DODAC. O conjunto de valores obtidos para αi e αe permitiram a análise quantitativa da catálise pelo compartimento aquoso interno e externo de vesículas sem a utilização de α como parâmetro ajustável. Foi modelado com sucesso a decomposição espontânea do íon 6-nitrobenzisoxazol-3-carboxilato e a hidrólise alcalina do ácido 5,5\'-ditiobis(2-nitrobenzóico). Este trabalho é a primeira análise quantitativa de reações modificadas por vesículas nos dois compartimentos usando dados independentes para dissociação iônica das superfícies vesiculares. The relative extents of ion dissociation (α) from micelles of hexadecyltrimethylammonium (CTA) chloride (CTACl) and bromide (CTAB) and vesicles of dioctadecyldimethylammonium (DODA) chloride (DODAC) and bromide (DODAB) were determined using a dediazoniation method. The dediazoniation method consists in the determination of the products resulting from the slow spontaneous decomposition of 2,4,6-trimethylbenzene diazonium tetrafluoroborate, followed by fast reaction of the resulting phenyl cation with neighboring nucleophiles. This method was shown to determine the relative composition of the interaggregate aqueous pseudophase and, consequently, the degree of ion dissociation of the aggregate. The values of α obtained for CTACl and CTAB were, respectively, 0.29 and 0.26, in excellent agreement with previously published values. The ion exchange selectivity coefficient for bromide/chloride exchange, determined using the same method was 2.65, coinciding with published data. These values lend confidence to the use of this method for obtaining both relative dissociation degrees and ion selectivity coefficients. The method was also applied for the determination of the external (αe)as well as the internal (αi) α of DODAC and DODAB vesicles. For tip-sonicated DODAB vesicles αe was 0.20, for bath-sonicated DODAC αe was 0.20, for tip-sonicated DODAC αe was 0.25 and for large DODAC vesicles a was 0.11. We also determined, for the ftrst time, the a value of 0.07 for αi of large vesicles. The set of values obtained for αi and αe permitted quantitative analysis of two reaetions in both the internal and external aqueous compartments of vesicles without recourse to ion dissociation adjustable parameters. We successfully modeled the spontaneous decomposition of 6-nitrobenzisoxazol-3-carboxylate and the alkaline hydrolysis of 5,5\'-dithiobis(2-nitrobenzoate). This work is the first quantitative analysis of vesicle-modified reactions in both vesicle compartments using independent data for ion dissociation from vesicle\'s surfaces.

APA, Harvard, Vancouver, ISO, and other styles

46

Makhlouf, Thabet. "Etude de la catalyse acide générale dans la réaction d'hydrolyse d'orthoesters en milieu micellaire inversé de dioctysulfoccinate de sodium." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37615571p.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Carion-Taravella, Brigitte. "Formation de vésicules par voie enzymatique : application à la transition micelle-vésicule." Compiègne, 1998. http://www.theses.fr/1998COMP1101.

Full text

Abstract:

Une étude physico-chimique d'une catalyse en milieu microstructuré auto-évolutif est proposée. Une enzyme est utilisée afin de faire auto-évoluer un système mixte lipide-détergent, de modifier la nature des phases en présence, et de former des vésicules. Des vésicules de dipalmitoylphosphatidylcholine (DPPC)-dodécyl-Beta-glucopyranoside (DG) sont fabriquées à partir de micelles mixtes DPPC-dodécyl - Beta-D-maltoside (DM) suite à l'hydrolyse du DM par l'amyloglucosidase en DG. Les diagrammes pseudo-binaires DPPC-DM et DPPC-DG en milieu dilué sont étudiés dans l'intervalle de température 10-45°C et de composition 0-1. 8 (rapport molaire détergent/lipide), par des techniques d'analyse thermique différentielle et de diffraction des rayons X corrélées par des mesures de turbidité, des analyses en chromatographie d'exclusion sur gel et en microscopie électronique par cryofracture. Le diagramme pseudo-ternaire à 37°C de mélanges DPPC-DG-DM est également établi par des mesures de turbidité, des études de diffraction de rayons X, de chromatographie d'exclusion sur gel et de microscopie électronique. Enfin, le comportement de l'enzyme dans le diagramme pseudo-ternaire DPPC-DG-DM est étudié (dosage des détergents par HPLC en phase inverse) et les objets formés au cours de la réaction enzymatique sont caractérisés par chromatographie d'exclusion sur gel et par microscopie électronique (cryofracture). La structure moléculaire de la tête polaire du détergent (DM : maltose et DG : glucose) a un effet important sur la nature des phases formées. L'enzyme permet de se déplacer dans le diagramme pseudo-ternaire DPPC-DG-DM de la phase micellaire vers la phase lamellaire et aboutit à la formation de vésicules hétérogènes en taille (10-80 nm). La disparition des micelles affecte considérablement la vitesse de la réaction enzymatique, cette dernière est directement liée à la disponibilité du DM fortement diminuée en présence de structure lamellaire.

APA, Harvard, Vancouver, ISO, and other styles

48

Burger, Benjamin Jean-Baptiste François. "Tensio-actifs macrocycliques chiraux dérivés de sucres : synthèse, propriétés de complexation, auto-agrégation et application pour la mise en oeuvre de réactions sélectives en milieu micellaire aqueux." Versailles-St Quentin en Yvelines, 2005. http://www.theses.fr/2005VERS0015.

Full text

Abstract:

In order to promote an environmentally friendly chemistry, regio and enantioselective reactions in aqueous surfactant media have been studied. The study of the ring opening of styrene oxide in micellar solution of a catonionic surfactant (DTAB) shows that the chimioselectivity (Hydrolysis/Bromolysis) and the regioselectivity (/ bromohydrine) depend on the partitioning and the location of the substrate within the surfactant aggregates. A chiral surfactant (DAC12) containing two sugar-based surfactant blocks covalently linked to a macrocycle has been prepared, its cation-binding ability and aggregation properties have been studied. Bromolysis of 2,3-epoxypropylbenzene as well as Michael additions have been performed in aqueous micellar solutions of DAC12. Small enantiomeric excess are obtained for bromolysis. Additions of -ketoesters to unsaturated ketones are not enantioselective, despite an increase in reaction speed in the presence of DAC12. Finally, it is shown that Lewis-acid catalyzed Michael additions can be performed without solvent or surfactant, with very good yields Ce travail est consacré à l'étude de la régio- et stéréosélectivité de réactions en milieu micellaire aqueux. L'étude de l'ouverture de l'époxystyrène en solution micellaire aqueuse d'un tensioactif cationique (bromure de dodécyltriméthyl ammonium) montre que la chimiosélectivité (hydrolyse/bromolyse) et la régio-sélectivité sont contrôlées par la partition et son orientation dans les agrégats. Un tensio-actif chiral (DAC12) constitué de deux blocs amphiphiles dérivés du glucose liés à un macrocycle a été préparé, ses propriétés de complexation et d'agrégation étudiées. Des réactions d'ouverture d'époxyde et d'additions de Michael ont été réalisées en solutions aqueuses micellaires de DAC12. Une légère énantiosélectivité est observée lors de la bromolyse du 2,3-époxypropylbenzène par contre l'addition de -cétoesters sur des cétones conjuguées, bien que favorisée en présence de DAC12, n'est pas stéréosélective. Ces additions-1,4, catalysées par des acides de Lewis Cu(II) ou Eu(III), peuvent être réalisées sans solvant ni tensio-actif avec d'excellents rendements

APA, Harvard, Vancouver, ISO, and other styles

49

Costa, Maria de Fatima Carvalho. "Propriedades estruturais e cataliticas de micelas mistas de dodecanoato de sodio/n-butanol." reponame:Repositório Institucional da UFSC, 1997. http://repositorio.ufsc.br/xmlui/handle/123456789/77340.

Full text

Abstract:

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciencias Fisicas e Matematicas Made available in DSpace on 2012-10-17T03:10:46Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T21:44:38Z : No. of bitstreams: 1 108797.pdf: 2401340 bytes, checksum: ff9434a0ed4c94373cf186fbc1fc1555 (MD5) Os efeitos do n-butanol sobre propriedades micelares, estruturais e catalíticas do dodecilsulfato de sódio (SDS) e dodecanoato de sódio (SDOD) foram investigados e comparados com respeito à influência do grupo cabeça dos surfactantes. Foram determinados os valores de concentração micelar crítica (CMC), grau de ionização (a), pH aparente (pHap) e polaridade destes detergentes, em soluções aquosas na ausência e na presença de n-butanol. O número de agregação micelar médio () do SDOD e o de micelas mistas SDOD/n-butanol foram determinados usando o método de Turro. Os efeitos da adição de n-butanol nas propriedades catalíticas de soluções aquosas 0,10 M de SDS (pH 9,15) e 0,10 M de SDOD (pH 9,05), a 25,0°C foram estudados através de medidas de constante de velocidade observada (Kobs) para a reação de hidrólise de anidrido benzóico.

APA, Harvard, Vancouver, ISO, and other styles

50

MOUKAWIM, MOHAMED. "Combinaison de la catalyse micellaire par differents sels d'hexadecyltrimethylammonium a contre-ions reactifs ou inertes et de la pseudo-catalyse par les ions hydroperoxydes pour la destruction de triesters phosphoriques par hydrolyse." Paris 7, 1995. http://www.theses.fr/1995PA077142.

Full text

Abstract:

L'hydrolyse de cinq triesters phosphoriques phosphate de diphenyle et de p-nitrophenyle, phosphate de di-p-tolyle et de p-nitrophenyle, phosphate de diphenyle et de p-cyanophenyle, phosphate de di-p-ditolyle et de p-cyanophenyle et phosphate de diethyle et de p-nitrophenyle (paraoxon) a ete etudiee dans des conditions de pseudo-catalyse par les ions ho#-#2, en equilibre avec h#2o#2, et en presence ou non de micelles d'ions hexadecyltrimethylammonium (cetyltrimethylammonium, cta#+). Les nouveaux tensioactifs ctax prepares (x = hydroperoxyde, acetate, metaborate) permettent de supprimer ou de reduire les effets inhibiteurs des contre-ions. De fortes reactivites sont alors observees. (par exemple, dans les solutions de ctaooh, le temps de demi-vie du paraoxon, triester connu pour etre difficilement hydrolysable, descend a une valeur de 1-2 seconde). Le ph des solutions et les constantes de vitesse d'hydrolyse sont interpretees quantitativement en termes d'association et d'echange des ions, ceci en tenant compte des variations du facteur global d'associations des ions avec les micelles, ainsi que de celle de la concentration de tensioactif non micellise. La prise en compte de ces facteurs constitue une amelioration importante du traitement pie (pseudo-phase ion exchange) classique. Bien que cela soit souvent admis, mais sans preuve, il est montre que la constante de vitesse de la reaction a l'interface des micelles est proportionnelle a la fraction molaire partielle, #hoo, des ions qui y sont presents. Lorsque la reaction est effectuee en presence de tampon borate et de h#2o#2, ce qui correspond a de fortes proportions d'ions perborates, seuls les ions ho#-#2 sont responsables de la pseudo-catalyse nucleophile. Les ions perborates sont des inhibiteurs de la catalyse micellaire, par suite de leur association a l'interface

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Micellar catalysi'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles