Effects of Ionic Liquids on the Nucleofugality of Dimethyl Sulfide

The
nucleofugality of dimethyl sulfide was measured in solvent
mixtures containing ionic liquids. The first-order rate constants
of the solvolysis of sulfonium salts were determined in mixtures containing
different proportions of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide in ethanol, representing the first
report on the solvolysis of a charged species in an ionic liquid.
Temperature-dependent kinetic studies allowed determination of activation
parameters and rationalization of observed solvent effects in different
ionic liquid mixtures. From the solvolysis data, the nucleofugality
of dimethyl sulfide in different proportions of this ionic liquid
in ethanol was determined. Further, the nucleofugality of dimethyl
sulfide was determined in mixtures containing high proportions of
each of seven other ionic liquids in ethanol. These data allowed quantification
of the effects of varying both the amount of ionic liquid present
and on changing the components of the ionic liquid on the nucleofugality
of dimethyl sulfide. The ionic liquid mixtures were shown to affect
the nucleofugality of this nucleofuge in a different manner to the
previously studied monatomic charged nucleofuges, owing to different
microscopic interactions in solution. This work highlighted the necessity
of considering electrofuges with an appropriate range of electrofugality
values along with the importance of the nucleofuge-specific sensitivity
parameter.