Thermodynamic characteristics of the dissolution of glycine, glycylglycine, and glycylglycylglycine in aqueous solutions of sodium dodecyl sulfate at Т = 298.15 K

Abstract

the enthalpies of dissolution of glycine (Gly), glycylglycine (GlyGly), and glycylglycylglycine (GlyGlyGly) are measured in aqueous solutions of sodium dodecyl sulfate (SDS) at SDS concentrations m = 0–0.7 mol kg⁻¹ and Т = 298.15 K by means of calorimetry. The obtained data are used to calculate the standard values of enthalpies of dissolution (Δ_solH^m) and enthalpies of transfer (Δ_trH^m) of glycine and its oligomers from water to SDS aqueous solutions. The dependences of Δ_solH^m and Δ_trH^m on SDS concentration in an aqueous solution at a constant concentration of glycine and its oligomers are determined. A comparative analysis of the thermodynamic characteristics of Gly, GlyGly, and GlyGlyGly transfer within the studied range of SDS concentrations is performed. The results are interpreted in terms of ion–ion, ion–polar, and hydrophobic interactions between SDS and molecules of glycine and its oligomers.