The solvation of L-serine in mixtures of water with some aprotic solvents at 298.15 K

The integral enthalpies of solution Δ_sol H ^m of L-serine in mixtures of water with acetonitrile, 1,4-dioxane, dimethylsulfoxide (DMSO), and acetone were measured by solution calorimetry at organic component concentrations up to 0.31 mole fractions. The standard enthalpies of solution (Δ_sol H°), transfer (Δ_tr H°), and solvation (Δ_solv H°) of L-serine from water into mixed solvents were calculated. The dependences of Δ_sol H°, Δ_solv H°, and Δ_tr H° on the composition of aqueous-organic solvents contained extrema. The calculated enthalpy coefficients of pair interactions of the amino acid with cosolvent molecules were positive and increased in the series acetonitrile, 1,4-dioxane, DMSO, acetone. The results obtained were interpreted from the point of view of various types of interactions in solutions and the influence of the nature of organic solvents on the thermochemical characteristics of solutions.