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|Type:||Artigo de periódico|
|Title:||Interaction Of Alkyl P-hydroxybenzoates With Micelles: Evaluation Of Their Partition Coefficients And Ionization Constants|
|Abstract:||This paper reports the partition coefficients for the neutral and anionic species of the homologous series of alkyl p-hydroxybenzoates (from methyl to pentyl) with CTAB micelles at 15, 25, and 35°C. These values are compared to literature data for the same compounds and some discrepancies found are attributed to the solute ionization in the earlier results. Solute pKa values are also reported in the presence of cationic, anionic, and nonionic micelles, in accordance with the qualitative Hartley's rule. These effects increase with the solute hydrophobicity due to a stronger interaction with micelles. The ΔpKa values are related to the partition coefficients using literature models, allowing us to evaluate the PPIE selectivity constants for the exchange between the solute anions and Br- with CTAB micelles. Both partition coefficients and ΔpKa slightly decrease as the temperature increases, in agreement with the current view of the hydrophobic interaction. The effect of solutes on the CMC of CTAB is ascribed to the intensity of solute partition and to their ionization. © 1992.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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