Study of molecular interactions and preferential solvation in binary mixtures of cyclohexane and (C5–C10) 1-alkanol by Kirkwood-Buff integrals

Abstract

Mixtures formed by cyclohexane + 1-alkanol have been investigated in the framework of the Kirkwood–Buff theory of solution. The alcohols considered are 1-pentanol up to 1-decanol. Data for the Kirkwood–Buff integrals, Gij excess or deficit number of molecules around the central ones, Δnij and coefficients of linear solvation, δij are reported. For solutions with a given cyclohexane, the increase in the CH2 groups of alcohols chain causes a decrease in G12 by the following sequences: 1-decanol > 1-nonanol > 1-octanol > 1-heptanol > 1-hexanol > 1-pentanol. The comparison of G12 and other calculated parameters for cyclohexane + 1-alkanol mixtures reveals that the interactions between similar molecules are more outstanding and the decrease in the alkyl chain of alcohols leads to the weakening of interactions related to the self–association of 1-alkanol, differences in the free volumes, hydrophobic interactions, and structural changes. These trends are consistent with experimental data on the excess molar volumes.