Enthalpies of interaction of hydroxylic solutes with organic solvents

Abstract

Heats of solution of m-cresol, 1-butanol, 1-pentanol, t-amyl alcohol, and model compounds (toluene, ethyl ether, n-butyl methyl ether, t-butyl methyl ether) in 17 organic solvents (n-heptane, cyclohexane, carbon tetrachloride, 1,2-dichloroethane, α,α,α-trifluorotoluene, triethylamine, butyl ether, ethyl acetate, dimethylformamide, dimethyl sulfoxide, benzene, toluene, mesitylene, t-butyl alcohol, 1-octanol, methanol, 2,2,2-trifluoroethanol) have been combined with solute heats of vaporization to give solvation enthalpies (ΔH(v → S)). Dependencies of solute vs. model solvation enthalpy differences on solvent dipolarity–polarizability and hydrogen-bond-accepting basicity were determined via correlations with Taft–Kamlet solvatochromic parameters (π*, β, ξ).m-Cresol is a substantially stronger H-bond donor than 1-butanol, 1-pentanol, and t-amyl alcohol, and H-bonds to acceptor solvents including alcohols. Cresol acts as an H-bond acceptor with the strong H-bond donor solvent trifluoroethanol.