The enthalpies of solution of tetraethyl-and tetrabutylammonium bromides in aqueous solutions of hexamethylphosphorus triamide at 328.15 K

摘要

The heats of solution of Et4NBr and Bu4NBr in water and aqueous solutions of hexamethylphosphorus triamide (HMPT) at 328.15 K were measured in a variable-temperature isothermic-shell calorimeter. The standard enthalpies of solution were calculated using the Debye-Hückel second-order theory. The enthalpy parameter of electrolyte-amide pair interactions was determined in terms of the McMillan-Mayer formalism. The processing of the data obtained in this work and previously led us to conclude that heat capacity changes caused by pair interactions of Et4NBr and Bu4NBr with HMPT were negative and independent of temperature over a wide temperature range. The methyl and methylene groups interacted with HMPT without heat capacity changes and, consequently, the enthalpies and entropies of their interactions with HMPT were constant over a wide temperature range.