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Aqueous solubility of some natural phenolic compounds / Fatima L. Mota in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5182–5189 Titre : Aqueous solubility of some natural phenolic compounds Type de document : texte imprimé Auteurs : Fatima L. Mota, Auteur ; António J. Queimada, Auteur ; Simao P. Pinho, Auteur ; Eugénia A. Macedo, Auteur Année de publication : 2008 Article en page(s) : p. 5182–5189 Note générale : Bibliogr. p. 5188-5189 Langues : Anglais (eng) Mots-clés : Hydroxybenzoic  acids;  Phenylpropenoic  acids;  Shake-flask  method Résumé : In this work, the aqueous solubilities of two hydroxybenzoic acids (gallic and salicylic acid) and three phenylpropenoic acids (trans-cinnamic, ferulic, and caffeic acids) are addressed. Measurements were performed, as a function of temperature, between 288.15 and 323.15 K, using the shake-flask method for generating the saturated aqueous solutions, followed by compositional analysis by spectrophotometric and gravimetric methods. The pH values of the saturated aqueous solutions were measured by potentiometry. Additional thermodynamic properties, which are fundamental for a better understanding of the solubilization process, as well as necessary for the modeling studies, such as melting temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC). Apparent acid dissociation constants (Ka) were obtained by potentiometry titration. The measured data were modeled with the cubic-plus-association (CPA) equation of state (EoS). This EoS is applied, for the first time, for multifunctional associating molecules, and the results indicate that it can adequately be used to represent the measured and other literature data with satisfactory accuracy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071452o [article] Aqueous solubility of some natural phenolic compounds [texte imprimé] / Fatima L. Mota, Auteur ; António J. Queimada, Auteur ; Simao P. Pinho, Auteur ; Eugénia A. Macedo, Auteur . - 2008 . - p. 5182–5189. Bibliogr. p. 5188-5189 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5182–5189 Mots-clés : Hydroxybenzoic  acids;  Phenylpropenoic  acids;  Shake-flask  method Résumé : In this work, the aqueous solubilities of two hydroxybenzoic acids (gallic and salicylic acid) and three phenylpropenoic acids (trans-cinnamic, ferulic, and caffeic acids) are addressed. Measurements were performed, as a function of temperature, between 288.15 and 323.15 K, using the shake-flask method for generating the saturated aqueous solutions, followed by compositional analysis by spectrophotometric and gravimetric methods. The pH values of the saturated aqueous solutions were measured by potentiometry. Additional thermodynamic properties, which are fundamental for a better understanding of the solubilization process, as well as necessary for the modeling studies, such as melting temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC). Apparent acid dissociation constants (Ka) were obtained by potentiometry titration. The measured data were modeled with the cubic-plus-association (CPA) equation of state (EoS). This EoS is applied, for the first time, for multifunctional associating molecules, and the results indicate that it can adequately be used to represent the measured and other literature data with satisfactory accuracy. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071452o

Free energy of transfer of a methylene group in biphasic systems of water and ionic liquids [C3mpip] [NTf2], [C3mpyrr] [NTf2], and [C4mpyrr] [NTf2] / Filipa M. Maia in Industrial & engineering chemistry research, Vol. 51 N° 23 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 23 (Juin 2012) . - pp. 8061-8068 Titre : Free energy of transfer of a methylene group in biphasic systems of water and ionic liquids [C3mpip] [NTf2], [C3mpyrr] [NTf2], and [C4mpyrr] [NTf2] Type de document : texte imprimé Auteurs : Filipa M. Maia, Auteur ; Oscar Rodriguez, Auteur ; Eugénia A. Macedo, Auteur Année de publication : 2012 Article en page(s) : pp. 8061-8068 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Thermodynamic  properties  Ionic  liquid  Biphasic  system  Free  energy Résumé : Three hydrophobic ionic liquids (ILs) based on the bis(txifluoromethylsulfonyl)imide anion were studied in terms of the relative hydrophobicity of the equilibrium phases. The ILs were 1-methyl-1-propylpiperidinium bis-(trifluoromethylsulfonyl)imide, [C3mpip][NTf2]; 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide, (C3mpyrr]-[NTf2j; and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [C4mpyrr](NTf2]. In addition, the liquid-liquid phase diagrams were determined for two of the ILs, namely, [C3mpip][NTf2] and [C3mpyrr][NTf2]. The compositions of the equilibrium phases were obtained using a gravimetric technique in the temperature range from 278.15 to 343.15 K. The immiscibility gaps for these systems were found to be very large, with that for the system [C3mpip][NTf2] + water being slightly wider than that for the system [C3mpyrr][NTf2] + water. Partition coefficients for a series of dinitrophenylated (DNP) amino acids in the three systems at 296.15 K were experimentally determined. The DNP amino acids were found to distribute preferentially to the water-rich phase, and the partition was more extreme for the system with [C3mpip][NTf2]. The experimental partition coefficients decreased as the size of the alkyl side chain in the solutes increased. The relative hydrophobicity of the equilibrium phases was assessed by means of the free energy of transfer of a methylene group between the phases, ΔG(CH2), calculated from the partition coefficients of the series of solutes. It was found that the relative hydrophobicity between the phases follows the order [C4mpyrr][NTf2] > [C3mpip][NTf2] > [C3mpyrr][NTf2]. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25990318 [article] Free energy of transfer of a methylene group in biphasic systems of water and ionic liquids [C3mpip] [NTf2], [C3mpyrr] [NTf2], and [C4mpyrr] [NTf2] [texte imprimé] / Filipa M. Maia, Auteur ; Oscar Rodriguez, Auteur ; Eugénia A. Macedo, Auteur . - 2012 . - pp. 8061-8068. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 23 (Juin 2012) . - pp. 8061-8068 Mots-clés : Thermodynamic  properties  Ionic  liquid  Biphasic  system  Free  energy Résumé : Three hydrophobic ionic liquids (ILs) based on the bis(txifluoromethylsulfonyl)imide anion were studied in terms of the relative hydrophobicity of the equilibrium phases. The ILs were 1-methyl-1-propylpiperidinium bis-(trifluoromethylsulfonyl)imide, [C3mpip][NTf2]; 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide, (C3mpyrr]-[NTf2j; and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [C4mpyrr](NTf2]. In addition, the liquid-liquid phase diagrams were determined for two of the ILs, namely, [C3mpip][NTf2] and [C3mpyrr][NTf2]. The compositions of the equilibrium phases were obtained using a gravimetric technique in the temperature range from 278.15 to 343.15 K. The immiscibility gaps for these systems were found to be very large, with that for the system [C3mpip][NTf2] + water being slightly wider than that for the system [C3mpyrr][NTf2] + water. Partition coefficients for a series of dinitrophenylated (DNP) amino acids in the three systems at 296.15 K were experimentally determined. The DNP amino acids were found to distribute preferentially to the water-rich phase, and the partition was more extreme for the system with [C3mpip][NTf2]. The experimental partition coefficients decreased as the size of the alkyl side chain in the solutes increased. The relative hydrophobicity of the equilibrium phases was assessed by means of the free energy of transfer of a methylene group between the phases, ΔG(CH2), calculated from the partition coefficients of the series of solutes. It was found that the relative hydrophobicity between the phases follows the order [C4mpyrr][NTf2] > [C3mpip][NTf2] > [C3mpyrr][NTf2]. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25990318

Gibbs free energy of transfer of a methylene group in buffer + ionic liquid biphasic systems / Oscar Rodriguez in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5165–5168 Titre : Gibbs free energy of transfer of a methylene group in buffer + ionic liquid biphasic systems Type de document : texte imprimé Auteurs : Oscar Rodriguez, Auteur ; Pedro P. Madeira, Auteur ; Eugénia A. Macedo, Auteur Année de publication : 2008 Article en page(s) : p. 5165–5168 Note générale : Bibliogr. p. 5168 Langues : Anglais (eng) Mots-clés : Dinitrophenylated  amino-acids;  Ionic  liquid  system Résumé : Partitioning experiments for a series of dinitrophenylated (DNP) amino-acids have been conducted in three (ionic liquid + sodium phosphate buffer) biphasic systems at 23 °C. The ionic liquids used were 1-hexyl-3-methylimidazolium tetrafluoroborate ([C6mim][BF4]), 1-octyl-3-methylimidazolium tetrafluoroborate ([C8mim][BF4]), and 1-decyl-3-methylimidazolium tetrafluoroborate ([C10mim][BF4]). The pH of the initial aqueous solution has been fixed at 7.4, using a sodium phosphate buffer. DNP−amino acids distribute preferentially to the ionic liquid phase, and this partition increases with the length of the alkyl chain of the amino acid. The Gibbs free energy of transfer for a methylene group is calculated from the partition coefficients of the solutes. This provides a measurement for the relative hydrophobicity of the conjugated phases, and the obtained values are compared to those of other biphasic systems used in biotechnology (e.g., polymer−polymer and polymer−salt aqueous two-phase systems). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0714293 [article] Gibbs free energy of transfer of a methylene group in buffer + ionic liquid biphasic systems [texte imprimé] / Oscar Rodriguez, Auteur ; Pedro P. Madeira, Auteur ; Eugénia A. Macedo, Auteur . - 2008 . - p. 5165–5168. Bibliogr. p. 5168 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5165–5168 Mots-clés : Dinitrophenylated  amino-acids;  Ionic  liquid  system Résumé : Partitioning experiments for a series of dinitrophenylated (DNP) amino-acids have been conducted in three (ionic liquid + sodium phosphate buffer) biphasic systems at 23 °C. The ionic liquids used were 1-hexyl-3-methylimidazolium tetrafluoroborate ([C6mim][BF4]), 1-octyl-3-methylimidazolium tetrafluoroborate ([C8mim][BF4]), and 1-decyl-3-methylimidazolium tetrafluoroborate ([C10mim][BF4]). The pH of the initial aqueous solution has been fixed at 7.4, using a sodium phosphate buffer. DNP−amino acids distribute preferentially to the ionic liquid phase, and this partition increases with the length of the alkyl chain of the amino acid. The Gibbs free energy of transfer for a methylene group is calculated from the partition coefficients of the solutes. This provides a measurement for the relative hydrophobicity of the conjugated phases, and the obtained values are compared to those of other biphasic systems used in biotechnology (e.g., polymer−polymer and polymer−salt aqueous two-phase systems). En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0714293