Self-Diffusion and Molecular Association in a Cyclohexane–Methanol Binary System at Temperatures of 298 and 323 K

Self-diffusion in a cyclohexane–methanol binary system was studied by the pulsed gradient spin-echo 1 H NMR method at temperatures of 298 (in the region of limited miscibility) and 323 K (over entire composition of the mixed solvent). According to the data obtained, the concentration dependences of...

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Bibliographic Details
Published in:Russian Journal of Physical Chemistry A 2024, Vol.98 (3), p.353-357
Main Author: Golubev, V. A.
Format: Article
Language:English
Subjects:
Chemical equilibrium
Chemical Thermodynamics and Thermochemistry
Chemistry
Chemistry and Materials Science
Concentration gradient
Cyclohexane
Diffusion coefficient
Einstein equations
Methanol
Miscibility
NMR
Nuclear magnetic resonance
Physical Chemistry
Self diffusion
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Summary:Self-diffusion in a cyclohexane–methanol binary system was studied by the pulsed gradient spin-echo 1 H NMR method at temperatures of 298 (in the region of limited miscibility) and 323 K (over entire composition of the mixed solvent). According to the data obtained, the concentration dependences of the self-diffusion coefficients of cyclohexane increase with methanol concentration. However, the concentration dependences of the self-diffusion coefficients of methanol have minima. At the same time, according to 1 H NMR data, the chemical shift of OH protons in the methanol molecule decrease with increasing cyclohexane concentration and temperature, which indicates a decrease in the degree of methanol self-association in the system. The effect of molecular association on methanol self-diffusion in the binary system was evaluated using the Stokes–Einstein equation. The concentration dependences of the relative effective hydrodynamic radius of methanol were shown to have maxima.
ISSN:0036-0244
1531-863X
DOI:10.1134/S0036024424030075