Phase equilibria of branched isomers of C10-alcohols and C10-alkanes in supercritical ethane

Phase equilibrium data is presented for binary systems of C10-alcohol isomers (1-decanol, 2-decanol, 3,7-dimethyl-1-octanol, 2,6-dimethyl-2-octanol and 3,7-dimethyl-3-octanol) and C10-alkane isomers (n-decane, 2-methylnonane, 3-methylnonane and 4-methylnonane) with supercritical ethane. The measurements were conducted in a high pressure view cell at temperatures from 308 K to 348 K and compositions from 0.0120 to 0.662 mass fraction C10-compound. It was found that the position of the hydroxyl group and the presence of methyl branches have a large influence on the solubility of the C10-alcohol isomers. The closer the hydroxyl group is positioned to the centre of the molecule, the less polar the compound, and the more soluble it is in the non-polar solvent. The presence of methyl branches also increases the solubility of the alcohol, possibly due to the shielding it provides to the hydroxyl group. The phase transition pressures of the compounds decreased in the following order: 1-decanol, 3,7-dimethyl-1-octanol, 2-decanol, 2,6-dimethyl-2-octanol, 3,7-dimethyl-3-octanol, n-decane and its isomers. The phase transition pressures of the isomers of n-decane did not differ significantly from one another within the temperature and composition range studied.

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► Phase equilibria of ethane and C10-alkanes or C10-alcohols.
► Higher phase transition pressure for mixtures with alcohols than with alkanes.
► Side branching and OH-position influence ethane + alcohol phase equilibria.
► Negligible effect of alkane methyl-branching on phase equilibria.