The partition coefficients of benzothiophene (BT) and benzothiophene 1,1-dioxide (BTDO) in the octane/ acetonitrile system were predicted using the COSMO (conductor-like screening model) based activity coefficient models COSMO-SAC (segment activity coefficient) and COSMO-UNIQUAC. In COSMO-UNIQUAC, a segment activity coefficient was described in a UNIQUAC-type equation. The results with COSMO-UNIQUAC were compared with those from the COSMO-SAC model. It was found that COSMO-UNIQUAC reproduced the experimental data more accurately than COSMO-SAC. The surface charge density profiles (σ-profiles) of functional groups on BT and BTDO molecules were utilized to determine that the partition coefficients of BTDO are much lower than those of BT. A hypothetical molecule with the volume and surface area of BTDO was conducted by using the σ-profiles of functional groups on BT and BTDO. The partition coefficients of the hypothetical component were predicted by COSMO-UNIQUAC. It was revealed that the partitions of BTDO in the octane/acetonitrile system were influenced from the charge density changes by the oxidation on not only the sulfur atom but also on the carbon and hydrogen atoms.
All Science Journal Classification (ASJC) codes
- General Chemistry
- General Chemical Engineering
- Industrial and Manufacturing Engineering