Solubilities, partition coefficients, density, and surface tension for imidazoles plus octan-1-ol or plus water or plus n-decane

The solid-liquid equilibrium (SLE) has been measured from 270 K to the melting temperature of the solid for eight binary mixtures of imidazoles (1H-imidazole, 2-methyl-1H-imidazole, 1,2-dimethylimidazole, benzimidazole, and 2-methylbenzimidazole) with either octan-1-ol or water using a dynamic method. The melting temperature and enthalpy as well as the heat capacity change at the melting temperature were determined using differential scanning calorimetry (DSC). It was observed that the solubility of 1H-imidazole, 2-methyl-1H-imidazole, and 1,2-dimethylimidazole is much higher in water than in octan-1-ol. The solubility of benzimidazole and 2-methylbenzimidazole is much higher in octan-1-ol. Experimental solubility data were correlated using the Wilson, UNIQUAC ASM, and NRTL 1 models. The solid-solid first-order phase transition has been observed with 2-methyl-1H-imidazole, benzimidazole, and 2-methylbenzimidazole. The best description of the experimental solubility data was obtained by the NRTL I equation. The average root-mean-square deviation on the equilibrium temperatures obtained with solutions of five imidazoles in octan-1-ol is 2.1 K. The solubility data were used to calculate the octan-1-ol/water partition coefficients as a function of temperature. The surface tension of air/octan-1-ol or air/n-decane systems as well as the interfacial tension of octan-1-ol/water or n-decane/water were determined as a function of imidazole concentration at 298.15 K and 308.15 K.