Enthalpic Interactions of Formamide with d-Mannitol and d-Sorbitol in Aqueous Sodium Chloride Solutions at 298.15 K

Abstract

The enthalpies of mixing of formamide with d-mannitol and d-sorbitol and their respective enthalpies of dilution in aqueous sodium chloride solution have been determined by using flow-mix-isothermal microcalorimetry at 298.15 K. These experimental results have been used to determine the heterotactic enthalpic interaction coefficients (hxy, hxxy, and hxyy) according to the McMillan−Mayer theory. It has been found that the heterotactic enthalpic pairwise interaction coefficients (hxy) between formamide and d-mannitol in aqueous sodium chloride solution are positive and become more positive with an increase in the molality of sodium chloride. In contrast, the hxy between formamide and d-sorbitol varies from a negative value to a positive one and increases with the elevated molality of sodium chloride. The results are discussed in terms of solute−solute interaction and solute−solvent interaction.