Journal of Chemical and Engineering Data, Vol.63, No.5, 1443-1453, 2018
H-Bonding in 2,2,2-Trifluoroethanol: Application of the Stokes-Einstein-Sutherland Equation to Self-Diffusion and Viscosity at High Pressures
Self-diffusion coefficients at 254-348 K obtained by spin echo NMR and viscosities at 263-343 K obtained with a falling-body viscometer are reported at pressures up to 350 MPa for 2,2,2-trifluoroethanol (TFE). Along the coexistence curve, the transport coefficients vary as exp(A + B/T-2) (Avramov equation with n = 2); at high pressures, the temperature dependence is more complex, varying as exp(A + B/T + C/T-2); therefore, the temperature dependence changes with increasing pressure. Unlike non-H bonded liquids, Stokes Einstein Sutherland (SES) self-diffusion viscosity plots do not fall on a single line; the isotherms are approximately parallel and are of smaller slope (t approximate to 0.84-0.90) than the atmospheric pressure line (t approximate to 1). In this, TFE is like methanol, ethanol, and propanol. Such SES behavior is suggested as a diagnostic for self-association in H-bonded liquids. TFE does not meet the requirements for thermodynamic scaling.