THE INTERNAL STRUCTURES OF LIQUID N-METHYLFORMIDE - N,N-DIMETHYLFORMAMIDE BINARY-MIXTURES

The H-1-NMR spectra of liquid binary mixtures N-methylformamide (NMF) - N, N-dimethylformamide (DMF), were recorded at 298 K within nearly t he whole range of mixed solvent compositions. From these data were fou nd the values of the spectral structural parameter, Delta delta(NMF - DMF). The viscosities (eta(12)) of the mixed solvents were measured at 298.15 K, as well as the relative permittivities (epsilon(12)) and th e surface tensions (sigma(12)) at 291.15 K, 298.15 K and 303.15 K. Fro m all these data their deviations from ideality were calculated. Addit ionally, the temperature coefficients of relative permittivity, alpha( 12) = 1/epsilon(12) [d epsilon(12)/d(1/T)] and temperature coefficient s of surface tensions, gamma(12) = -(sigma(12)/ dT), were found. These quantities, as a function of a mole fraction, deviate very little fro m their molar values, indicating that the mixtures of NMF - DMF can be regarded as almost ideal.