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Doctoral Thesis
DOI
10.11606/T.46.2016.tde-04102016-171350
Document
Author
Full name
Erika Batista Tada
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2004
Supervisor
Committee
EL Seoud, Omar A. (President)
Amaral, Antonia Tavares do
Areas, Elizabeth Pinheiro Gomes
Donate, Paulo Marcos
Eberlin, Marcos Nogueira
Title in Portuguese
Emprego de sondas solvatocrômicas no estudo de solvatação em solventes puros, misturas de solventes e soluções micelares
Keywords in Portuguese
Água interfacial
Físico-química orgânica
Micelas
Polaridade
Soluções
Solvatação Preferencial
Solvatocromismo
Solvente
Tensoativos
Abstract in Portuguese
Neste trabalho, sondas solvatocrômicas foram empregadas no estudo da solvatação em solventes puros e misturas aquosas de solventes polares práticos e apráticos. A partir da polaridade de misturas aquosas de solventes orgânicos, determinou-se a concentração de água interfacial de micelas catiônicas. Finalmente, avaliou-se o efeito da polaridade e força iônica interfaciais de micelas catiônicas sobre a velocidade da reação entre p-nitrofenildifenilfosfato e o íon fluoreto. No estudo de misturas aquosas de solventes orgânicos, um novo modelo de solvatação preferencial foi elaborado, segundo o qual três espécies presentes em solução competem pela camada de solvatação da sonda: água, solvente orgânico e o "complexo" formado por uma molécula de água e outra de solvente orgânico (Solv-Água). Através deste modelo, analisou-se o efeito da temperatura e das propriedades das sondas e dos solventes orgânicos sobre o fenômeno da solvatação. Em soluções aquosas de micelas catiônicas, observou-se uma desidratação da interface em função do aumento do grupo hidrofílico do tensotativo e da mudança de geometria micelar de esférica para cilíndrica. Verificou-se que a velocidade da reação entre pnitrofenildifenilfosfato e fluoreto é pouco afetada pela interface micelar e pode ser reproduzida, na ausência de micelas, em soluções com mesma concentração de água e força iônica que as micelas.
Title in English
Employment solvatochromic probes in the study of solvation in pure solvents, solvent mixtures and micellar solutions
Keywords in English
Interfacial water
Micelles
Organic physical chemistry
Polarity
Solutions
Solvation Preferred
Solvatochromism
Solvent
Surfactants
Abstract in English
Solvatochromic probes have been employed to study the polarity of pure solvents and binary mixtures of water with protic and aprotic polar solvents. From polarity data of aqueous organic mixtures, the concentration of interfacial water of cationic micelles has been determined. In aqueous solutions of cationic micelles, the dehydration of interfacial region has been observed as a result of increasing the volume of the surfactant head group and changing micellar geometry from spherical to cylindrical. Finally, the effect of interfacial polarity and ionic force on the rate of the reaction between 4-nitrophenyldiphenylphosphate and fluoride ion has been evaluated. In studying aqueous organic mixtures, a new preferential solvation model has been developed, that considers the competition between three species in solution for the probe micro-solvation shell: water, organic solvent and a 1:1 "complex" formed by water and organic solvent (Solv-Água). Based on this new model, the effect of temperature, as well as probe and organic solvent properties on solvation has been analyzed. It has been observed that the rate of the reaction between p-nitrophenyldiphenylphosphate and fluoride ion shows little dependence on the properties of interfacial region of cationic micelles and can be reproduced, in the absence of micelles, in solutions containing the same water concentration and ionic force as the micellar pseudo-phase.
 
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Publishing Date
2016-10-04
 
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