Solute–solvent interactions in chemical and biological systems. IV. Correlations of Δ G , Δ H and T Δ S of transfer of aliphatic and aromatic solutes from 2,2,4‐trimethylpentane to aqueous solution

Δ G , Δ H and T Δ S of transfer of 25 aliphatic and aromatic solutes from 2,2,4‐trimethylpentane to aqueous buffer (pH 7) at 298 K have been examined in terms of intrinsic volumes and the solvatochromic parameters π*, δ, β and α of the pure solutes Correlations of the form\documentclass{article}\pagestyle{empty}\begin{document}$$ XYZ = XYZ_0 + {{mV_{\rm I} } \mathord{\left/ {\vphantom {{mV_{\rm I} } {100}}} \right. \kern-\nulldelimiterspace} {100}} + s\pi ^* + d\delta + d\beta + a\alpha $$\end{document}indicate that the thermodynamic quantities of transfer are unequally affected by solute properties; most notably, for aromatic solutes the cavity term mV I /100 is a principal (unfavorable) factor affecting T Δ S , but has little effect on Δ H . Transfer to water is favored by increasing solute π* (dipolarity–polarizability), β (H‐bond basicity) and α (H‐bond acidity), because water has greater dipolarity, H‐bond acidity and H‐bond basicity than trimethylpentane. Hydrogen bonding contributes exothermically to Δ H , but unfavorably to T Δ S , as would be expected from a loss of transitional entropy. Correlations of Δ G , Δ H and T Δ S with solute V I /100, β, α, μ 2 and polarizability function [( n 2 − 1)/( n 2 + 2)] give closely comparable results.