Enthalpic pair-interaction coefficients of benzene, aniline and nitrobenzene with N,N-dimethylformamide and acetonitrile in water at 298.15 K

The enthalpies of benzene and nitrobenzene solution in the highly aqueous water–N,N-dimethylformamide and water–acetonitrile mixtures have been measured at 298.15 K calorimetrically and compared with the results reported earlier for aniline. The enthalpic coefficients (hxy) of the solute–organic cosolvent pair interaction in water were computed. The –NO2 and –NH2 group increments to the pair-interaction coefficients were estimated. It was found that the interaction of –NO2 and –NH2 groups with the aprotic cosolvent molecule in water differs strongly—for the former group the interaction is strongly thermochemically repulsive, but for the latter one it is attractive. The investigation of the solutes behaviour in highly diluted aqueous solutions indicated the extreme sensitivity of the aromatic solutes to the presence of cosolvent molecules in water that increases from aniline to nitrobenzene.