Enthalpies, heat capacities and apparent molal volumes of transfer of some amino acids from water to aqueous t-butanol

Abstract

Integral enthalpies of solution at 298 and 308 K and densities at 298 K of some amino-acid solutions in aqueous t-butanol were measured as a function of t-butanol mole fraction. The integral enthalpies, heat capacities, and apparent molal volumes of transfer of amino acids from water to aqueous t-butanol solutions were derived from these data. The results are discussed in terms of solute–solute and solute–solvent interactions. Coefficients of pair, triplet and higher-order interactions involving solute and cosolvent molecules have been calculated from the transfer functions. The relative contribution of various hydrophilic and hydrophobic interactions in these solutions have been inferred from the sign and magnitude of the interaction coefficients.