Thermal properties of n-R4NBr solutions in binary solvents containing formamide

Abstract

The enthalpies of solution of tetraethyl- and tetra-n-hexylammonium bromides have been measured in mixtures of formamide with ethylene glycol at 298.15 and 313.15 K in the whole mole fraction range by the calorimetric method. The standard enthalpies of solution in binary mixtures have been calculated with Redlich–Rosenfeld–Meyer type equation. The enthalpy and heat capacity parameters of pair interaction of organic electrolytes with EG in FA and with FA in EG have been computed and discussed. The enthalpy interaction parameters of single ions with EG in FA medium have been evaluated and compared with those for ion–water and ion–MeOH interaction in FA. The standard heat capacities of solution have been evaluated. The excess enthalpies of solution, ΔsolHE, of Et4NBr, Bu4NBr, and Hex4NBr have been determined. The ΔsolHE values are positive for Et4NBr and negative for Bu4NBr and Hex4NBr and become more negative from Bu4NBr to Hex4NBr.