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This thesis is presented in two parts. In part one, the excess molar volumes and the excess molar enthalpies have been determined for several binary systems at 298.15 K using an LKB flow microcalorimeter and/or a 2277 Thermal Activity Monitor and an Anton Paar Digital Densitometer. The excess molar volumes and excess molar enthalpies, V; and H; , have been determined for systems involving an alkanol (I-propanol, 2-propanol) mixed with a hydrocarbon (1hexene, I-heptene, l-octene, I-hexyne, I-heptyne, l-octyne). The results show trends relating to the degree of unsaturation of the hydrocarbon to the position of the hydroxyl group on the alkanol. The excess molar volumes and excess molar enthalpies, V; and H; of di-n-butylamine + diethyl ether or dipropyl ether or di-l-methylethyl ether or dibutyl ether or 1,1 dimethylethyl methyl ether or 1,1 dimethylpropyl methyl ether or tetrahydrofuran or tetrahydropyran or 1,4 dioxane have been measured over the whole composition range at the temperature 298.15 K in order to investigate di-n-butylamine - ether interactions. The V; values for each of the systems studied are negative with the exception of the mixtures of (di-n-butylamine + dibutyl ether or tetrahydrofuran or tetrahydropyran or 1,4 dioxane. The H; results over the whole mole fraction range are formed endothermically. Measurements were also made on mixtures involving (a cycloalkane + a pseudocycloalkane). The congruency theory was tested for the (cycloalkane + pseudo-cycloalkane) mixture. The cycloalkane mixtures studied here did not satisfy the null test of the congruency principle. In the second part of this thesis the main aim of the investigation was to apply ambient temperature hydrogen peroxide bleaching techniques to a novel non-woven fabric and to optimize the treatment conditions for this technique. Five cold-pad batch bleaching formulas were applied to the non-woven and the sample fabrics were analyzed for the following properties a) fluidity (measure of degree of degradation of the cotton fibre as a result of the bleaching process) b) wettability (absorbency) c) whiteness (using instrumental techniques) d) inherent fibre surface properties (SEM) A method was elucidated for the cold batch bleaching of the non-woven which produced a fabric with minimum fibre damage, an acceptable degree of whiteness and excellent absorbency properties. The treatment parameters of time (Xl), temperature(x2) and hydrogen peroxide concentration (x3) for this method were optimised using a multiple regression analysis for three variables and response surface plots. / Thesis (M.Sc.)-University of Natal, Durban, 1993.

Molecular rotational motions are known to influence both Raman scattering of light and nuclear spin relaxation. Therefore, the application of Raman bandshape analysis and NMR relaxation time measurements to probe molecular dynamics in liquids will provide us with a deeper understanding of the dynamical behavior and structure of molecules in the liquid phase. Presented here are (i) studies of molecular reorientation of acetonitrile in the neat liquid phase and in solution by Raman bandshape analysis and NMR relaxation; (ii) studies of reorientational dynamics and internal rotation in transition metal clusters by NMR relaxation.

Ce travail de thèse porte sur l’étude d’électrolytes pour utilisation dans des systèmes de stockage énergétiques tels que les batteries lithium-ions. Les matériaux spécifiques à cette étude sont des liquides ioniques à base de pyrrolidinium avec le fluorosulfonylimide (FSI) en tant que contre-ion, le tout dopé au lithium.La méthode de caractérisation principale est la spectroscopie par Résonance Magnétique Nucléaire (RMN) qui peut être utilisée pour résoudre la structure, la dynamique ou encore l’arrangement spatial entre les anions et les cations. Des mesures de diffusion et des expériences de relaxation réseau-spin, utilisant 1H pour les cations, 19F pour les anions et 7Li, sont effectuées pour étudier le transport ionique dans le liquide ainsi que la rotation moléculaire respective des différents ions.Toutefois, dans le but de mieux comprendre le mécanisme de transport des ions à un niveau moléculaire dans ces liquides ioniques, l’expérience Heteronuclear Overhauser Effect SpectroscopY (HOESY) a été employée. Cette technique est basée sur le transfert d’aimantation entre deux isotopes nucléaires dans l’espace. Puisque le transfert est généralement dû à des interactions de courtes portées, des informations concernant les différentes proximités des espèces dans le liquide sont obtenues.Une grande partie de cette étude est concentrée sur le développement de la technique HOESY elle-même, avec l’amélioration de la séquence d’impulsion RMN mais aussi de l’analyse du signal, dans l’optique d’une étude quantitative et du développement d’une procédure automatique et systématique d’ajustement des données théoriques aux données expérimentales. Des simulations par Dynamique Moléculaire (DM) et des mesures de relaxation RMN sont utilisées pour permettre l’analyse des expériences OESY, permettant alors d’accéder à la corrélation des distances entre les noyaux et des paramètres de relaxation tels que les temps de corrélation, pouvant permettre une meilleure compréhension du transport ionique. En plus du développement de cette technique, de nouveaux liquides ioniques incluant des chaînes alkyles plus longues, des cycles plus longs ou encore un groupe ethero-alkyle sur la chaine alkyle sont étudiés par HOESY dans le ut d’observer l’impact de la structure du cation sur les interactions ioniques. Une autre technique complémentaire, la polarisation dynamique nucléaire, est aussi adoptée afin d’étudier les liquides ioniques dans un état vitreux imitant leur structure à l’état liquide. / This work is focused on the study of electrolytes for energy storage devices such as lithium ion batteries. The specific materials are pyrrolidinium-based ionic liquid electrolytes with bis-fluorosulfonylimide (FSI) as the counter anion, and also containing lithium.The main experimental method of characterization is Nuclear Magnetic Resonance (NMR) spectroscopy, which can be used to probe structure, dynamics and spatial arrangements between anions and cations. NMR-based diffusion measurements or spin lattice relaxation experiments, using 1H for cations, 19F for anions and 7Li, are used to study the ionic transport in the liquid and the molecular tumbling of the different ions respectively.However, in order to attempt to better understand the ion transport mechanism at the molecular level in these ionic liquids, the HOESY (Heteronuclear Overhauser Effect SpectroscopY) experiment is used. This technique is based on a transfer of magnetization through space between two different nuclear isotopes. As this transfer is generally mediated by short-range interactions, it provides information on which species are close together in the liquid.A large part of this work is based on the development of the HOESY technique itself, both improving the implementation of the NMR pulse sequence to reduce the experimental time, but also improving ways to analyze the resulting data in a quantitative way and developing an automatic and systematic data fitting procedure. Molecular Dynamics (MD) simulations and NMR relaxation measurements are also used to assist the HOESY analysis, allowing correlations with distances between nuclei and motional parameters such as correlation times to be established, which will lead to a better understanding of the ion interactions. In addition to this technique development, others ionic liquids including longer alkyl, longer cycle or even an ether-o-alkyl group on the alkyl chain, are studied by HOESY in order to observe the impact of the cation structure on the ionic interactions. Another complementary technique, dynamic nuclear polarization, is also used in order to study the ionic liquid in the glassy state structure which mimics the liquid state.

A reação peroxioxalato está sendo amplamente utilizada para as mais variadas aplicações analíticas e bioanalíticas, porém, esta transformação é pouco estudada em meios aquosos, importantes principalmente para aplicações bioanalíticas. Neste trabalho foi estudada a reação de oxalato de bis(2,4,6-triclorofenila) (TCPO) com peróxido de hidrogênio (H2O2), em 1,2-dimetoxietano e em água, catalisada por 2,6-lutidina (2,6-dimetilpiridina). Observou-se que a reação ocorre com essa base agindo como um catalisador não-nucleofílico. A reação peroxioxalato foi realizada também em tampão borato onde a espécie reativa é a base conjugada do H2O2. A partir da dependência da constante de velocidade de decaimento da intensidade de emissão (kobs) com a concentração de peróxido de hidrogênio e do tampão borato se obtiveram evidências que a reação neste meio ocorre por catálise básica específica. Por último, a reação foi estudada em meio tampão borato contendo os líquidos iônicos (LIs) tetrafluoroborato de 1-butil-3-metilimidazólio (bmimBF4), cloreto de 1-alil-3- metilimidazólio (AmimCl) e acetato de 1-alil-3-metilimidazólio (AmimAc). A presença dos LIs no tampão resulta em um aumento dos rendimentos de formação de estados excitados singlete (Φs). Contrariamente, o aumento da concentração de sais comuns, como cloreto e acetato de tetrabutilamonio e NaCl, causou a diminuição dos valores dos rendimentos quânticos de quimiluminescência. As constantes de velocidade observadas aumentaram tanto com a concentração dos LIs quanto dos sais comuns. Os valores dos rendimentos quânticos de quimiexitação obtidos foram correlacionados com os parâmetros de viscosidade e polaridade das misturas. De maneira geral, foi mostrado neste trabalho que a reação peroxioxalato pode ser conduzida em meios essencialmente aquosos e a presença de LIs leva a um aumento do rendimento quântico de emissão, fatos importantes para potenciais aplicações analíticas. / The peroxyoxalate reaction is being widely used for a variety of analytical and bioanalytical applications, however, this transformation is very little studied in aqueous media, important mainly for bioanalytical applications. In this work was studied the reaction of bis(2,4,6-trichlorophenil) oxalate (TCPO) with hydrogen peroxide (H2O2) in 1,2-dimethoxyethane and water catalyzed by 2,6-lutidine (2,6-dimethylpyridine) was studied and it is observed that it occurs with this base acting as a non-nucleophilic catalyst. The peroxyoxalate reaction was also performed in aqueous borate buffer where the reactive species is the conjugate base of H2O2. Evidence is obtained that this reaction occurs through specific base catalysis from the dependence of the emission decay rate constant (kobs) with the hydrogen peroxide and borate buffer concentration. Finally, the reaction was studied in borate buffer media containing the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-allyl-3-methylimidazolium acetate (AmimAc). The presence of ILs in the buffer results in a concentration dependend increase of the yields of excited state formation (Φs). In contrast, the increase of the concentration of common salts, such as tetrabutylammonium chloride, tetrabutylammonium acetate and NaCl, caused a decrease in the emission quantum yields. The observed rate constants increased with both, the concentration of ILs and common salts. The chemiexcitation quantum yields values obtained were correlated with the viscosity and polarity parameters of the mixtures. In conclusion, it was shown in this work that the peroxyoxalate reaction can be conducted in essentially aqueous media and the presence of ILs leads to an increase in the emission quantum yields, important facts for potential analytical applications.

Dephasing vibracional de dissulfeto de carbono líquido em diferentes pressões foi estudado por dinâmica molecular. Teoria de pertubação permite estudar relaxação vibracional com o método bem estabelecido de dinâmica molecular de equilíbrio de moléculas rígidas. Além do potencial intermolecular efetivo do tipo Lennard-Jones usado para a simulação de CS2 , é também assumido um potencial efetivo de acoplamento entre os graus de liberdade vibracional, translacional e rotacional. É discutido em detalhes a importância dos termos repulsivo e atrativo neste potencial, assim como a anisotropia das interações. As simulações reproduzem satisfatoriamente a dependência com a densidade observada experimentalmente para a função de correlação vibracional e para o desvio de frequência vibracional entre as fases líquida e gasosa. As simulações indicam pequena correlação entre relaxação vibracional e reorientacional, a qual pode ser mostrada como resultante do acoplamento desses graus de liberdade com movimento translacional. Um modelo estocástico entre as é desenvolvido para investigar a correlação funções de correlação vibracional e reorientacional, e resultados similares são obtidos por simulação e teoria. As simulações por dinâmica molecular também mostraram que a função de correlação de flutuação de frequência vibracional de CS2 não é uma simples exponencial. Então, a conhecida fórmula de Kubo para a função de correlação vibracional não é válida, e é sugerido um modelo duplo-exponencial para a função memória vibracional. / Vibrational dephasing of liquid carbon disulfide at different pressures is investigated by molecular dynamics simulation. Pertubation theory allows one to use the well-stablished method of equilibrium molecular dynamics of rigid molecules in studying vibrational dephasing. Besides the effective three-centre Lennard-Jones intermolecular potential for the simulation of CS2 , an effective coupling potential between vibrational, translational and rotational degrees of freedom is also assumed. The role of repulsive and attractive terms in this potential, as well as anisotropy, is discussed. The experimental trends of the average vibrational frequency shift between gas and liquid phase and vibrational correlation function with density are well reproduced by molecular dynamics. The simulations indicate a small correlation between vibrational and reorientational relaxations, which can be shown as the result of the coupling of these degrees of freedom with translational motion. A stochastic model is developed to investigate the correlation between vibrational and reorientational correlation functions. Very similar correlation is obtained from both theory and computer simulation. The simulations also showed that correlation functions of vibrational frequency fluctuations of CS2 are not a single exponential. Thus, the well known Kubo\'s formula for the vibrational correlation function is not valid for CS2 , and a double exponential model for the memory function is introduced.

A produção de biodiesel etílico é uma questão estratégica para a política energética nacional, uma vez que o Brasil é um dos maiores produtores de oleaginosas do mundo e o segundo maior produtor de etanol, álcool de origem renovável. Neste sentido, o presente trabalho buscou promover a transesterificação de óleos vegetais por etanol assistido por líquidos Iônicos sob diferentes fontes de aquecimento. O glicerol foi transformado em compostos de valor agregado e de interesse industrial. O mesmo foi modificado in situ após a reação de transesterificação gerando biodiesel aditivado pelos derivados da glicerina, conforme esquema 1. (Ver arquivo) / The production of ethyl biodiesel is a strategic issue for the national energy policy, because Brazil is one of the largest producers of oilseeds and the second largest producer of ethanol, a renewable alcohol. In this way, this work aimed to promote the transesterification of vegetable oils with ethanol assisted by ionic liquids under different heat sources. Glycerol was transformed into valuable compounds of industrial interest. It was also modified in situ after the transesterification reaction generating additive ethyl biodiesel, as shown below. (See file)

A produção de biodiesel etílico é uma questão estratégica para a política energética nacional, uma vez que o Brasil é um dos maiores produtores de oleaginosas do mundo e o segundo maior produtor de etanol, álcool de origem renovável. Neste sentido, o presente trabalho buscou promover a transesterificação de óleos vegetais por etanol assistido por líquidos Iônicos sob diferentes fontes de aquecimento. O glicerol foi transformado em compostos de valor agregado e de interesse industrial. O mesmo foi modificado in situ após a reação de transesterificação gerando biodiesel aditivado pelos derivados da glicerina, conforme esquema 1. (Ver arquivo) / The production of ethyl biodiesel is a strategic issue for the national energy policy, because Brazil is one of the largest producers of oilseeds and the second largest producer of ethanol, a renewable alcohol. In this way, this work aimed to promote the transesterification of vegetable oils with ethanol assisted by ionic liquids under different heat sources. Glycerol was transformed into valuable compounds of industrial interest. It was also modified in situ after the transesterification reaction generating additive ethyl biodiesel, as shown below. (See file)

A reação peroxioxalato está sendo amplamente utilizada para as mais variadas aplicações analíticas e bioanalíticas, porém, esta transformação é pouco estudada em meios aquosos, importantes principalmente para aplicações bioanalíticas. Neste trabalho foi estudada a reação de oxalato de bis(2,4,6-triclorofenila) (TCPO) com peróxido de hidrogênio (H2O2), em 1,2-dimetoxietano e em água, catalisada por 2,6-lutidina (2,6-dimetilpiridina). Observou-se que a reação ocorre com essa base agindo como um catalisador não-nucleofílico. A reação peroxioxalato foi realizada também em tampão borato onde a espécie reativa é a base conjugada do H2O2. A partir da dependência da constante de velocidade de decaimento da intensidade de emissão (kobs) com a concentração de peróxido de hidrogênio e do tampão borato se obtiveram evidências que a reação neste meio ocorre por catálise básica específica. Por último, a reação foi estudada em meio tampão borato contendo os líquidos iônicos (LIs) tetrafluoroborato de 1-butil-3-metilimidazólio (bmimBF4), cloreto de 1-alil-3- metilimidazólio (AmimCl) e acetato de 1-alil-3-metilimidazólio (AmimAc). A presença dos LIs no tampão resulta em um aumento dos rendimentos de formação de estados excitados singlete (Φs). Contrariamente, o aumento da concentração de sais comuns, como cloreto e acetato de tetrabutilamonio e NaCl, causou a diminuição dos valores dos rendimentos quânticos de quimiluminescência. As constantes de velocidade observadas aumentaram tanto com a concentração dos LIs quanto dos sais comuns. Os valores dos rendimentos quânticos de quimiexitação obtidos foram correlacionados com os parâmetros de viscosidade e polaridade das misturas. De maneira geral, foi mostrado neste trabalho que a reação peroxioxalato pode ser conduzida em meios essencialmente aquosos e a presença de LIs leva a um aumento do rendimento quântico de emissão, fatos importantes para potenciais aplicações analíticas. / The peroxyoxalate reaction is being widely used for a variety of analytical and bioanalytical applications, however, this transformation is very little studied in aqueous media, important mainly for bioanalytical applications. In this work was studied the reaction of bis(2,4,6-trichlorophenil) oxalate (TCPO) with hydrogen peroxide (H2O2) in 1,2-dimethoxyethane and water catalyzed by 2,6-lutidine (2,6-dimethylpyridine) was studied and it is observed that it occurs with this base acting as a non-nucleophilic catalyst. The peroxyoxalate reaction was also performed in aqueous borate buffer where the reactive species is the conjugate base of H2O2. Evidence is obtained that this reaction occurs through specific base catalysis from the dependence of the emission decay rate constant (kobs) with the hydrogen peroxide and borate buffer concentration. Finally, the reaction was studied in borate buffer media containing the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-allyl-3-methylimidazolium acetate (AmimAc). The presence of ILs in the buffer results in a concentration dependend increase of the yields of excited state formation (Φs). In contrast, the increase of the concentration of common salts, such as tetrabutylammonium chloride, tetrabutylammonium acetate and NaCl, caused a decrease in the emission quantum yields. The observed rate constants increased with both, the concentration of ILs and common salts. The chemiexcitation quantum yields values obtained were correlated with the viscosity and polarity parameters of the mixtures. In conclusion, it was shown in this work that the peroxyoxalate reaction can be conducted in essentially aqueous media and the presence of ILs leads to an increase in the emission quantum yields, important facts for potential analytical applications.

Cheung, Wai Ming Edwin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 107-112). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.