Abstract
Densities and viscosities of formamide (FA)-, N-methylformamide (NMF)-, andN, N-dimethylformamide (DMF)-water mixtures were measured at 25°C under high pressure up to 200 MPa. The isothermal compressibility of the FA-water system decreases monotonously with an increase in the FA content at each pressure, but those of NMF-and DMF-water systems show a minimum against the composition in the water-rich region. Although the excess viscosity of the FA-water system is negative in the whole composition range, those of NMF-and DMF-water systems are positive. Such trends become remarkable with an increase in pressure. These results are discussed in terms of the hydrogen bonding between water and amide molecules and the hydrophobic hydration.
