Enthalpies of solution of tetra-n-butylammonium bromide in binary mixtures of water,formamide, N-methylformamide,and N,N-dimethylformamide

The enthalpies of solution of tetra-n-butylammonium bromide have been measured in mixtures of formamide (F) with water, N-methylformamide (NMF) with water, N,N-dimethylformamide (DMF) with water, F with NMF, DMF with F, and NMF with DMF at 25°C in the whole mole-fraction range. The enthalpies of solution vs composition profiles show a maximum value in the DMF-H₂O and in the DMF-F systems. In the F-NMF and NMF-DMF mixturesn-Bu₄NBr displays a nearly ideal behavior, whereas in the other solvent systems the excess enthalpy of solution deviates substantially from zero.