Excess enthalpies of [CnMIM][NTf2] n = (2 or 10) + ethanol or plus N-methyl-2-pyrrolidone binary mixtures at 298.15 K and 0.1 MPa

Mixtures containing 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [CIIMIM]{NTf2]n = {2, 10}, + ethanol or +N-methy1-2-pyrrolidone have been investigated to determine excess molar enthalpies, HE, and excess partial molar enthalpies of components, HE and Hz, over the entire mole fraction, x1, range, at 298.15 K and 0.10 MPa. Ionic liquids, ILs, were pre-treated by heating and by using activated molecular sieves. Both mixtures in ethanol are endothermic and the HE of the components are always positive while those in NMP are exothermic and the corresponding values of HE are negative, in the whole x1 range. The deviations from ideality are quite significant, being the HE values at equimolar composition, HEeq u; (+1800 +40 and + 2110 +10) J mo1-1 for ethanol -containing mixtures and (- 1410 +10 and -1980 +20) J mo1-1 for NMP-containing mixtures (u is the standard uncertainty). The values of the excess partial molar enthalpies at infinite dilution of the components, 11'`, show regular trends. The HE are always greater than the Hz; their ratio is about 1.8 for mixtures in EtOH and 2.5 for NMP-containing mixtures. The greatest thermal effects are found when the molecular compound acts as a solvent in the dissolution of one mole of IL, under extreme dilution condition.

Automated summary

This study investigated mixtures containing 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and ethanol or N-methy1-2-pyrrolidone, revealing the changes in excess molar enthalpies and excess partial molar enthalpies of components over the entire mole fraction range, as well as the thermal effects under extreme dilution conditions.