Distribution of a Monovalent Anion in Various Ionic Liquid/Water Biphasic Systems: Relationship of the Distribution Ratio of Picrate Ions with the Aqueous Solubility of Ionic Liquids

摘要

The distribution of picrate anions in various ionic liquid (IL)/water biphasic systems was investigated at 298.2 K-The ILs were l-butyl-3-methylimidazolium hexa-fluorophosphate, l-butyI-3-methylimidazolium bis-(trifluoromethanesulfonyl)amide, l-hexyl-3-methylimidazo-lium hexafluorophosphate, l-hexyl-3-methylimidazolium bis-(trifluoromethanesulfonyl) amide, l-methyl-3-octylimidazolium tetrafluoroborate, l-methyl-3-octylimidazo-lium hexafluorophosphate, l-methyl-3-octylimidazolium bis-(trifluoromethanesulfonyl)amide, l-methyl-3-octylimidazo-lium bis(pentafluoroethanesulfonyl)amide, l~butyl-2,3-dime-thvlimidazolium bisf'trifluoromethanesulfonvnamide. 1-butvl-1 methylpyrrolidmium bis(trifluoromethanesulfonyl)amide, methyltrioctylammonmm bis(trifluoiomethanesulfonyl)amide, 1 butyhmidazolmm bis(trifluoromethanesulfonyl)amide, and 1 butylpyrrolidiruum bis(trifluoromethanesulfonyl)amide The distribution ratios in dilute conditions (D°) and the aqueous solubilities of the ILs (square root of the solubility product, K_(sp) ) were determined The extractability of the picrate anion generally increases with increasing hydrophobicity of the IL cation (C~+) and increasing hydrophilicity of the IL anion (A ) For the ILs with different C~+ but the same AT, the log D° vs log K_(sp) plot generally gives a linear relationship with a slope of—1, when the ILs have similar K_(sp)~(1/2) values, the D° value decreases m the C~+ order, protic cations 1,3 dialkylimidazohum cations >other cations For the ILs comprising different A but the same C~+, the log D° versus log K_(sp)~(1/2) plot is close to a linear line with a slope of 1 These regularities can be explained on the basis of the extraction mechanism including both the ion pair extraction with C~+ and the ion exchange with A~-