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(CH30H)/D(CH302H) z 1.11 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.

NMR Studies on Effects of Temperature, Pressure, and Fluorination on Structures and Dynamics of Alcohols in Liquid and Supercritical States

“…35,36 On the other hand, in MeOH, 3.53 × 10 -39 g/cm 3 was used as the perpendicular component of I, because I value for the principal axis is too small. 37 Unfortunately, calculation of the spin-rotation relaxation time using eq 6 is not usually possible, because the C eff value is not known for many molecules.…”

Assessment of diffusion coefficients of general solvents by PFG-NMR: Investigation of the sources error

“…In the past a significant number of the published diffusion coefficients for solvent molecules were obtained using the diaphragm and capillary-cell protocols [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39], and PFG-NMR [40][41][42][43][44][45][46][47]. However, the published values exhibit scatter and are not comparable because the first method requires tracer isotope molecules.…”

p,T Dependence of Self-diffusion in Fluoroethanols.

“…The strong decrease of A with falling temperature in the alcohols is thought to arise from the rising influence of hydrogen bonds upon molecular mobility when the system is cooled. Consequently, (1-A) has been proposed to indicate the degree of hydrogen bonding [11].…”

“…The modified hard-sphere theory has been applied successfully to describe self diffusion in a number of associated liquids [11,12]. Here, the self diffusion coefficient is described as the product of the calculated diffusion coefficient of smooth hard spheres, DSHS> and the parameter A, which was introduced by Chandler to take into account couplings of translational and rotational motion [13,14]:…”