Synthesis and Characterization of Ionic Liquids Incorporating the Nitrile Functionality

Abstract

A series of imidazolium salts with the nitrile functional group attached to the alkyl side chain, viz. [CnCNmim][X] (where CnCNmim is the 1-alkylnitrile-3-methylimidazolium cation and Cn= (CH2)(n), n = 1-4; X = Cl, PF(6), and BF(4)) and [C3CNdmim][X] (where CnCNdmim is the 1-alkylnitrile-2,3-dimethylimidazolium cation and C(n) = (CH2)(n), n = 3; X = Cl, PF(6), and BF(4)), have been prepared and characterized using spectroscopic methods. The majority of the nitrile-functionalized imidazolium salts can be classed as ionic liquids since they melt below 100 degrees C. Four of the imidazolium salts have been characterized in the solid state using single-crystal X-ray diffraction analysis to reveal an extensive series of hydrogen bonds between H atoms on the cation and the anion. The relationship between the solid-state structure and the melting point is discussed. Key physical properties (density, viscosity, and solubility in common solvents) of the low melting ionic liquid have been determined and are compared with those of the related 1-alkyl-3-methylimidazolium and 1-alkyl-2,3-dimethylimidazolium ionic liquids. It was envisaged that these ionic liquids could act as both solvent and ligand for catalyzed reactions, and this application is demonstrated in hydrogenation reactions, which show that retention of the catalyst in the ionic liquid during product extraction is extremely high.

Catalytic Applications of Metal Nanoparticles in Imidazolium Ionic Liquids

“…[53] Moreover, elegant investigations by Dyson and co-workers on functionalized ILs [85,86] such as imidazolium or pyridinium salts with the nitrile functional group attached to the alkyl side demonstrated that the ILs could act as both solvent and ligand for metal-catalyzed reactions. [87] For example, Pd 0 NPs immobilized in both N-butylpyridinium and nitrile-functionalized ILs show good catalytic activity for the Stille coupling reactions, but recycling and reuse is considerably superior in the nitrile-functionalized ionic liquid. [72] One of the most interesting applications of transitionmetal NPs dispersed ILs is the possibility of tuning the selectivity of the reaction, since in these multiphase catalytic processes the primary products can be extracted during the reaction thereby modulating the product selectivity (modifying the different substrates and the solubility of the reaction products with the catalyst containing phase).…”

Tuning the selectivity of ruthenium nanoscale catalysts with functionalised ionic liquids: Hydrogenation of nitriles

“…1), since it may stabilise the ruthenium nanoscale catalyst via nitrile binding without blocking the coordination of the substrates. Indeed, this ionic liquid was readily prepared and successfully applied by Dyson and co-workers for cross-coupling reactions by Pd nanoparticles [9,10].…”

Synthesis, Characterization and Theoretical Study of the New Aluminate Ionic Liquid: Tetrahepthylammonium-bromotrichloroaluminate [(C7H15)4N]+[AlCl3Br]-

“…Melting temperature of the eutectic is well below that of the AlCl 3 , representing the minimum liquid us temperature throughout the entire system. We continue to focus on the synthesis and characterization of various ionic liquids [12][13][14] . In this Ionic liquid was synthesized through a one-step reaction.…”