Abstract
The solubilities of 4-trifluoromethylbenzoic acid in supercritical carbon dioxide were measured by a flow type apparatus. The measurements were carried out at 308.2, 313.2 and 323.2 K and 9 to 23 MPa. The solubilities of 4-trifluoromethylbenzoic acid were compared with those of benzoic acid, non-fluorinated methylbenzoic acid isomers, and the other trifluoromethylbenzoic acid isomers to discuss the effects on the solubility by addition of the trifluoromethyl group and by substituting the methyl group to the trifluoromethyl group. The solubilities of 4-trifluoromethylbenzoic acid are lower than those of benzoic acid. The solubilities decrease by addition of trifluoromethyl group. The solubilities of 4-trifluoromethylbenzoic acid are almost the same as those of 4-methylbenzoic acid. The solubilities of 4-trifluoromethylbenzoic acid are lower than those of 2- and 3-trifluoromethylbenzoic acids. The solubilities of trifluoromethylbenzoic acid isomers are significantly affected by the position of trifluoromethyl group. The experimental solubilities were correlated by a solution model in which the regular solution model was combined with the athermal solution theory (Flory-Huggins theory). The correlation results show good agreement with the experimental data.
