Application of a new statistical mechanical model for calculating Kirkwood factors in self associating liquid systems to alkanol + CCl4 mixtures

Abstract

A recently developed statistical–mechanical model for calculating Kirkwood correlation factors g_K in self associating liquids and liquid mixtures has been applied for the simultaneous description of g_K derived from dielectric constant data, the molar enthalpy of mixing H^E_m, and the infrared absorbtion of monomeric alcoholic species as function of the composition in alkanol + CCl₄ mixtures. The alkanols are methanol, ethanol, propanol, butan-1-ol, pentan-1-ol, hexan-1-ol, octan-1-ol, sec-butanol, tert-butanol and pentan-3-ol. The majority of parameters involved in the theory are obtained by independent quantum mechanical ab initio calculations of molecular clusters consisting of up to four alcohol molecules. As a consequence only two parameters have to be adjusted freely to each binary system, a third parameter responsible for the non-specific intermolecular dispersion interaction has been adjusted within a limited range of possible values given by physical arguments. Excellent agreement between theory and experimental data for g_K, H^E_m and IR absorbance is obtained covering the whole range of concentration. The theory also rationalizes the temperature dependence of these properties without adjusting further parameters. The Kirkwood correlation factor g_K turns out to be a sensitive response to peculiarities of the molecular structure of hydrogen-bonded systems in the condensed liquid state.