Physicochemical properties of a binary mixture of N-methylimidazole and methanol

At atmospheric pressure and over a full molar fraction range, for a binary mixture of x N-methylimidazole + (1-x) methanol, the density, viscosity and refractive index at 308.15 K were measured, and the Gibbs energy of activation of viscous flow was calculated. All these properties were, respectively, correlated by a fourth-order polynomial. Based on these properties, the excess molar volume, viscosity deviation and refractive index deviation, and the excess Gibbs energy of activation of viscous flow, were calculated and fitted to a third-order Redlich-Kister polynomial, respectively. The total vapor pressure in the range (303.15-363.15) K was measured and correlated by a cubic equation, as well as the Clausius-Clapeyron equation. The molar enthalpy of vaporization was extrapolated from the Clausius-Clapeyron equation. The compositions of vapor-liquid coexisting phases were measured, and a temperature-composition phase diagram was plotted. A strong attractive molecular interaction between N-methylimidazole and methanol in a liquid mixture is discussed.