New Brønsted-Lewis Acidic Quaternary Ammonium Ionic Liquids: Synthesis, Acidity Determination and Acidity-Catalytic Activity Relationship

Spectroscopic determination of relative Brønsted acidity as a predictor of reactivity in aprotic ionic liquids.

A simple titration technique utilizing pyridine as a FTIR spectroscopy probe is demonstrated to successfully predict relative Brønsted acid-limited reaction rates in different ionic liquid (IL) environments. Relative acidity is shown to vary across three aprotic ILs in a manner that is specific to the particular acid-IL pairing.

Lewis Acidic Ionic Liquids

Until very recently, the term Lewis acidic ionic liquids (ILs) was nearly synonymous with halometallate ILs, with a strong focus on chloroaluminate(III) systems. The first part of this review covers the historical context in which these were developed, speciation of a range of halometallate ionic liquids, attempts to quantify their Lewis acidity, and selected recent applications: in industrial ...

New Brønsted Ionic Liquids: Synthesis, Thermodinamics and Catalytic Activity in Aldol Condensation Reactions

Protic pyridinium ionic liquids: Synthesis, acidity determination and their performances for acid catalysis

Three new protic ionic liquids based on 2-methylpyridinium were prepared and characterized. Their catalytic activities for the tert-butylation of phenol and the esterification of cyclic olefins with acetic acid were examined and satisfactory results were obtained over 2-methylpyridinium trifluoromethanesulfonate ([2-MPyH]OTf). Hammett method was used to determine the acidity order of these ioni...

Synthesis and Lewis acidity of fluorophosphonium cations.

A series of fluorophosphonium salts, [R3PF][X] (R = alkyl or aryl; X = FB(C6F5)3, [B(C6F5)4]), have been prepared by reactions of phosphine/borane frustrated Lewis pairs (FLPs) with XeF2 or difluorophosphoranes with [Et3Si][B(C6F5)4]. As the substituents bound to phosphorus become increasingly electron withdrawing, the corresponding fluorophosphonium salts are shown to be increasingly Lewis aci...