| Abstract
| - In this paper, we report the effect of ionic liquids on substitution reactions using a variety of anionicnucleophiles. We have combined new studies of the reactivity of polyatomic anions, acetate, trifuoroacetate,cyanide, and thiocyanide, with our previous studies of the halides in [C4C1py][Tf2N], [C4C1py][TfO],and [C4C1im][Tf2N] (where [C4C1im]+ is 1-butyl-3-methylimidazolium and [C4C1py]+ is 1-butyl-1-methylpyrrolidinium) and compared their reactivities, k2, to the same reactions in the molecular solventsdichloromethane, dimethylsulfoxide, and methanol. The Kamlet−Taft solvent descriptors (α, β, π*) havebeen used to analyze the rates of the reactions, which were found to have a strong inverse dependencyon the α value of the solvent. This result is attributed to the ability of the solvent to hydrogen bond tothe nucleophile, so reducing its reactivity. The Eyring activation parameters (ΔH⧧ and ΔS⧧), whileconfirming the reaction mechanism, do not offer obvious correlations with the Kamlet−Taft solventdescriptors.
|
