Solvent Properties of Aqueous Biphasic Systems Composed of Polyethylene Glycol and Salt Characterized by the Free Energy of Transfer of a Methylene Group between the Phases and by a Linear Solvation E
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- 作者：Heather D. Willauer ; Jonathan G. Huddleston ; and Robin D. Rogers
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2002
- 出版时间：May 29, 2002
- 年：2002
- 卷：41
- 期：11
- 页码：2591 - 2601
- 全文大小：102K
- 年卷期：v.41,no.11(May 29, 2002)
- ISSN：1520-5045
文摘
Aqueous biphasic systems (ABSs) composed of poly(ethylene glycol) (PEG) and salt have beenexamined as potential environmentally benign solvents for liquid/liquid extraction. These systemsmight also represent an alternative to traditional solvent/water systems used in quantitativestructure-activity relationships (QSARs). For the application and design of these systems, it isimportant to have a thorough understanding of the nature of the solvent and its interactionswith the solute, and thus, PEG/salt ABSs have been characterized to this end by a variety ofmethods. The relative hydrophobicities of several PEG/salt ABSs composed of different molecularweights of PEG (1000, 2000, and 3400) and a variety of inorganic salts [K3PO4, K2CO3, (NH4)2SO4, Li2SO4, MnSO4, ZnSO4, and NaOH] were measured by the free energy of transfer of amethylene group 
Delta.gif" BORDER=0 >GCH2. These results indicate that the relative hydrophobicity of a PEG/saltABS is a function of only the degree of phase divergence of the biphasic system as expressed bythe difference in polymer concentration between the phases [delta poly(ethylene glycol) (
PEG),delta ethylene oxide monomer (EO)] or the tie line length (TLL). The distributions of a widerange of solutes differing in structure and functionality were also measured in PEG/salt ABSs,and the results were compared to the corresponding 1-octanol/water partition coefficients. Thesedata were used to develop a linear free energy relationship (LFER) based on Abraham'sgeneralized solvation equation, enabling a direct comparison to be made between the solventproperties of PEG/salt ABSs and those of traditional solvent/water systems used, for example,in the determination of log P. Similar comparisons are also enabled with the properties of certainaqueous micellar systems.
Delta.gif" BORDER=0 >GCH2. These results indicate that the relative hydrophobicity of a PEG/saltABS is a function of only the degree of phase divergence of the biphasic system as expressed bythe difference in polymer concentration between the phases [delta poly(ethylene glycol) (PEG),delta ethylene oxide monomer (EO)] or the tie line length (TLL). The distributions of a widerange of solutes differing in structure and functionality were also measured in PEG/salt ABSs,and the results were compared to the corresponding 1-octanol/water partition coefficients. Thesedata were used to develop a linear free energy relationship (LFER) based on Abraham'sgeneralized solvation equation, enabling a direct comparison to be made between the solventproperties of PEG/salt ABSs and those of traditional solvent/water systems used, for example,in the determination of log P. Similar comparisons are also enabled with the properties of certainaqueous micellar systems.