Density, viscosity and electrical conductivity of alcohol solutions of 2,2-diethyl-1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide

Abstract

Density, viscosity and electrical conductivity are measured for the methanol and ethanol solutions of the ionic liquid (IL), 2,2-diethyl-1,1,3,3-tetramethylguanidinium bis(trifluoromethylsulfonyl)imide ([TMG(C2)2][NTf2]), at the molality up to 3 mol·kg−1, and the interactions are explored at the molecular level. The concentration dependence of the physicochemical properties is evaluated by empirical models including the Redlich–Kister, the Jones–Dole and the Casteel–Amis equations. The obtained interaction coefficients from viscosity measurements indicate the structure making effect in both systems, by which alcohol molecules gather around the ionic moieties through significant ion–dipole interactions. According to the calculated apparent molar volume and molar conductivity, ion aggregation occurs to form ion pairs when a specific concentration (c0) is reached. The IL behaves as a weak electrolyte in alcohols, and ethanol is more efficient to dissociate IL with a higher value of c0.