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摘要
The distribution behavior in ionic liquid/water biphasic systems of substituted benzenes, phenols, and phenolate anions was investigated in detail. The ionic liquids used were five common hydrophobic ones of 1-butyl-3-methylimidazolium, 1-methyl-3-octylimidazolium, and 1-butyl-1-methylpyrrolidinium cations. For electrically neutral solutes, the partition coefficients in the ionic liquid/water system are insensitive to the kind of the ionic liquid, and show a correlation with those in the 1-octanol/water system. From analysis based on the regular solution theory, the similarity in extraction ability between the ionic liquids and 1-octanol was attributed to the closeness of the solubility parameters of these solvents. The interaction energies between the polar substituents and the ionic liquids were also evaluated. It was revealed that the ionic liquids act as both Lewis acids and bases, like 1-octanol; however, they are weaker in basicity, but stronger in acidity, than 1-octanol. The ionic liquids can extract phenolate ions, and the extraction ability is governed by the hydrophobicity and hydrophilicity of the component cations and anions, respectively. The extraction of phenolate ions includes both the mechanisms of ion-pair extraction and ion exchange with the component ions. The model of the extraction equilibrium of anions with ionic liquids was established, and a regular relationship between the anion distribution ratio and the ionic liquid solubility product in water was found.
- 出版日期2013-4
