ACETONITRILE PLUS NITROMETHANE - AN EXAMPLE OF IDEAL SOLVENT MIXTURES

Densities, viscosities, static dielectric constants and refractive ind ices of acetonitrile + nitromethane mixtures in the temperature range between 5 and 45 degrees C are reported. Density and viscosity data, a nalyzed in terms of molar excess volumes and molar excess fluidities, show a weak interactions field between acetonitrile and nitromethane m olecules. Lorentz-Lorenz molar refractivities and Kirkwood correlation factors, obtained from refractive indices and dielectric constants da ta, respectively, indicate that such weak interactions can be attribut ed to an antiparallel alignment between neighboring dipoles of unlike solvent molecules. Such specific features do not significantly perturb the local structures of the pure components so that acetonitrile + ni tromethane mixtures can be considered, in a first approximation, one o f the few ideal solvent mixtures for which the physical properties can be determined by applying the additivity rules to the pure components .