Apparent Molar Volumes and Adiabatic Compressibilities of Some Amino Acids in Aqueous Sucrose Solutions at 298.15 K

Abstract

Abstract Apparent molar volumes V ϕ and adiabatic compressibilities K ϕ, s of L-glycine, L-alanine, and L-valine in aqueous sucrose solutions ranging from pure water to 25 mass% of sucrose have been determined at 298.15 K from precise density and sound speed measurements. Partial molar volumes V ϕ 0 and partial molar adiabatic compressibilities K ϕ, s 0 of these amino acids at infinite dilution were evaluated. These values are required for calculating hydration number n H of amino acids. Transfer volumes ΔV ϕ 0 and transfer adiabatic compressibilities ΔK ϕ, s 0 at infinite dilution from water to aqueous sucrose solutions have been calculated. Transfer parameters have been discussed in terms of solute-cosolute interaction on the basis of a cosphere overlap model. Group contributions for the partial molar volumes and adiabatic compressibilities have been determined from the amino acids. All these results indicate that hydrophilic ionic group interactions are stronger than the hydrophilic-hydrophobic interactions in all the amino acids over the whole concentration range of sucrose solutions and decrease with the increase in size of side chain of amino acids.