Partition Coefficients of Itaconates in Aqueous-Micellar Solutions: Measurements and Predictions with COSMO-RS

Abstract

The micelle–water partition coefficient KMW is measured for itaconic acid and some of its esters for micellar solutions of the surfactants sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and t-octylphenoxypolyethoxyethanol (Triton X-100). Additionally, KMW is predicted using the conductor-like screening model for real solvents (COSMO-RS) and calculated from log KMW–log KOW relations. We find that, because of the increasing length of the alkyl chain in the ester, KMW increases, and the COSMO-RS predicted values agree well with the experimental ones. Furthermore, COSMO-RS is used to screen the partitioning of the esters in micellar solutions of a homologous series of surfactants (NaCnS, n = 8–16). For hydrophobic solutes, we predicted an increase in KMW with increasing n, while for less hydrophobic solutes, KMW is constant.