Aqueous Brønsted–Lowry Chemistry of Ionic Liquid Ions

Abstract

Ionic liquids have become commonplace materials found in research laboratories the world over, and are increasingly utilised in studies featuring water as co-solvent. It is reported herein that proton activities, aH (+) , originating from auto-protolysis of H2O molecules, are significantly altered in mixtures with common ionic liquids comprised of Cl(-), [HSO4 ](-), [CH3SO4 ](-), [CH3COO](-), [BF4](-), relative to pure water. paH (+) values, recorded in partially aqueous media as -log(aH (+)), are observed over a wide range (∼0-13) as a result of hydrolysis (or acid dissociation) of liquid salt ions to their associated parent molecules (or conjugate bases). Brønsted-Lowry acid-base character of ionic liquid ions observed is rooted in equilibria known to govern the highly developed aqueous chemistry of classical organic and inorganic salts, as their well-known aqueous pKs dictate. Classical salt behaviour observed for both protic and aprotic ions in the presence of water suggests appropriate attention need be given to relevant chemical systems in order to exploit, or avoid, the nature of the medium formed.

On the Use of a Protic Ionic Liquid with a Novel Cation To Study Anion Basicity

“…[20][21][22] Most recenti st he development of an absolute pH scale based on the gas-phases tandard state of the proton, [23] which has already found applicationi nm ixed-solvent liquid chromatography. Other thermodynamic measures of the property,b oth from experiments andc alculations, have been reported and include gas phase proton affinities/basicities, [25,26] heats of reactions from calorimetry, [27,28] proton activity from its reduction potential [29][30][31][32] and partition coefficients between two phases from chromatography. Other thermodynamic measures of the property,b oth from experiments andc alculations, have been reported and include gas phase proton affinities/basicities, [25,26] heats of reactions from calorimetry, [27,28] proton activity from its reduction potential [29][30][31][32] and partition coefficients between two phases from chromatography.…”

“…[24] We make further reference to this in the discussion section. Other thermodynamic measures of the property,b oth from experiments andc alculations, have been reported and include gas phase proton affinities/basicities, [25,26] heats of reactions from calorimetry, [27,28] proton activity from its reduction potential [29][30][31][32] and partition coefficients between two phases from chromatography. [33] Anion basicity is also factored in equations to describe the polarity [34,35] of solvents in general and ionic liquidsi np articular.…”

Visible-light-driven CO2reduction to formate with a system of water-soluble zinc porphyrin and formate dehydrogenase in ionic liquid/aqueous media

“…An ionic liquid is a salt in the liquid state. [18][19][20][21][22][23][24][25][26][27] There are ionic liquids that remain liquid at low pressures close to vacuum and below À50 C. For example, ionic liquids that are liquid below À143 C have been proposed as the uid base for a spinning liquid-mirror telescope to be based on the Moon. 28 By dissolving frozen water molecules in an ionic liquid, thus, it might be a prerequisite for a light-driven CO 2 reduction system.…”

Synthesis of 2, 2, 4‐trimethyl‐1, 3‐pentaerediol monoisobutyrate catalyzed by homogeneous catalysis‐liquid/liquid separation catalytic system based on Bibasic sites Ionic Liquids

“…Water as solution was mainly because of its relatively polar, strong ionic interactions and internal pressure effects (H‐bonding) with BSILs. [ 11–14 ] Bibasic sites were confirmed by two endothermic peaks on the TG‐DCS curve of [Aemim]IMC. [ 15–17 ]…”