Self-diffusion in monohydric alcohols under pressure. Methanol, methan(2H)ol and ethanol

Abstract

Measurements are reported for the self-diffusion under pressures up to 300 MPa of methanol from 278 to 328 K and methan(²H)ol from 214 to 343 K. Data are also given for self-diffusion of ethanol under pressure, and ethan (²H)ol at 0.1 MPa, at 298 K. In methanol there is a large effect due to the isotopic substitution [D(CH₃OH)/D(CH₃O²H)≈ 1.1] and there appears to be a correlation with the square root of the moments of inertia of the two isotopic species. Ethanol shows a similar, but much smaller, effect. The data for methanol and methan(²H)ol are fitted well by a rough hard-spheres treatment with temperature-dependent roughness parameters and also by a smooth hard-spheres correlation with a temperature-dependent molecular diameter.