Heterotactic Enthalpic Interactions of L-Arginine with 2,2,2-Trifluoroethanol in Aqueous Solutions at 298.15, 303.15 and 310.15 K

The enthalpies of mixing of L-arginine with 2,2,2-trifluoroethanol and their respective enthalpies of dilution in aqueous solutions at 298.15, 303.15 and 310.15 K were determined as a function of the mole fraction by flow microcalorimetric measurement. These experimental results were analyzed to obtain heterotactic enthalpic interaction coefficients(hxy, hxxy, hxyy) according to the McMillan-Mayer theory. The hxy coefficients between L-arginine molecule studied and 2,2,2-trifluoroethanol molecule in aqueous solutions at 298.15, 303.15 and 310.15 K were found to be all negative. The results were discussed in terms of solute-solute interaction and solute-solvent interaction.