Diffusion Coefficients of Substituted Benzenes and Alcohols at High Dilution in Octan-1-ol

Abstract

Interdiffusion coefficients Dao in octan-1-ol of benzene, toluene, chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, bromobenzene, 1,2-dibromobenzene, and 1,4-dibromobenzene have been measured at 25 °C at average solute mole fractions from 0.001 to 0.000 05 using the Taylor dispersion technique. The Dao values range from 0.5 × 10-9 m2/s to 0.3 × 10-9 m2/s with standard deviations below 4% in all but the highest dilutions and show only minor (and statistically insignificant) variations with solute concentration. In addition, corresponding interdiffusion coefficients of methanol, ethanol, propan-1-ol, butan-1-ol, 2-methylpropan-2-ol and phenol were determined at average mole fractions around 0.0004. For both groups of compounds, distinct but separate dependencies of Dao on molecular size were observed. The results are discussed from the viewpoint of the Stokes−Einstein equation, and in comparison with literature data for the corresponding diffusion in water. The analysis reveals different dependencie...