Solid-liquid equilibria for systems containing long-chain 1-alkanols. II. Experimental data for 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol or 1-eicosanol + CCl 4 or + cyclohexane mixtures. Characterization in terms of DISQUAC

Abstract

Solid-liquid equilibrium (SLE) temperatures for 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol or 1-eicosanol + CCl 4 mixtures and for 1-dodecanol or 1-tetradecanol + cyclohexane systems have been measured by a dynamic method between 273 K to the melting point of the alcohol. First order transitions between different crystal forms (α, β, γ) of the alcohols were observed. The solid-solid transitions of these long-chain alcohols changed with the solvent as result of solute-solvent interactions. This behaviour is also encountered in many other systems. The hydroxyl/cyclohexane and hydroxy/CCl 4 interactions present in the investigated systems were characterized in terms of DISQUAC, reporting the interchange coefficients for such contacts. It is remarkable that these interchange coefficients remain constant for a given alcohol: from 1-octadecanol for mixtures with cyclohexane, and from 1-hexadecanol for those systems containing CCl 4. Calculations were developed taking into account the solid-solid transitions of the 1-alkanols. This is important because of the large value of the molar heat of the α → β transition. For mixtures containing alcohols other than 1-eicosanol the relative standard deviations for the equilibrium temperatures were less than 0.009. For mixtures containing 1-eicosanol the relative standard deviations were close to 0.020, because the model cannot, using the proposed interaction parameters, reproduce their negative deviations from Raoult's law.