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

The effect of temperature on the Dimroth-Reichardt E(T)(30) parameter of binary mixtures of dimethyl sulfoxide, acetonitrile and nitromethan e with alcohols and water was studied. The E(T)(30) polarity parameter of many of these binary mixtures exhibits a strong synergism. Dimethy l sulfoxide, acetonitrile and nitromethane form hydrogen-bonded comple xes with the alcohols more polar than themselves. The E(T)(30) values of the mixtures were fitted according to an earlier model, based on so lvent exchange equilibria, that allows calculation of the E(T)(30) val ues of the hydrogen-bonded complexes. The variation of the E(T)(30) va lues of the pure solvents and the hydrogen-bonded complexed solvents w ith temperature shows that the synergism decreases as the temperature increases.