SOLUTE-SOLVENT AND SOLVENT-SOLVENT INTERACTIONS IN BINARY SOLVENT MIXTURES. 2. EFFECT OF TEMPERATURE ON THE E_T(30) POLARITY PARAMETER OF DIPOLAR HYDROGEN BOND ACCEPTOR-HYDROGEN BOND DONOR MIXTURES

摘要

The effect of temperature on the Dimroth-Reichardt E_T(30) parameter of binary mixtures of dimethyl sulfoxide, acetonitrile and nitromethane with alcohols and water was studied. The E_T(30) polarity parameter of many of these binary mixtures exhibits a strong synergism. Dimethyl sulfoxide, acetonitrile and nitromethane form hydrogen-bonded complexes with the alcohols more polar than themselves. The E_T(30) values of the mixtures were fitted according to an earlier model, based on solvent exchange equilibria, that allows calculation of the E_T(30) values of the hydrogen-bonded complexes. The variation of the E_T(30) values of the pure solvents and the hydrogen-bonded complexed solvents with temperature shows that the synergism decreases as the temperature increases.