To achieve a successful liquid–liquid
extraction, the selection
of the biphasic system is crucial for the proper separation of the
solutes of interest. The number of biphasic systems that can be employed
is vast, requiring a large amount of time and cost to experimentally
determine the most suitable for each application. The use of computational
methods to predict partition coefficients in biphasic systems is of
great interest to design and select the most appropriate. COSMO-RS,
a quantum chemical computational tool that requires only the chemical
structure of the compounds for calculations, would be an ideal tool
for that purpose. Here, we present a systematic evaluation of COSMO-RS
as a predictive tool for partition coefficients. Its performance was
evaluated for the partitioning of 228 solutes in 9 binary and 3 ternary
organic biphasic systems (OBS). The results show that the use of COSMO-RS
with TZVPD_FINE parametrization allows for very good predictions.
They also show that predictions are greatly dependent on an accurate
description of the compositions of the phases in equilibrium. Thus,
the use of experimental mutual solubilities (binary OBS) or tie lines
(ternary OBS) when available is the most suitable option for this
purpose. In the case of using a total predictive tool, TZVPD_FINE
parametrization can properly predict both mutual solubilities and
tie lines, so it can also be used for the estimation of partition
coefficients in an OBS. Therefore, the COSMO-RS method is demonstrated
here to be a useful and reliable tool to predict partition coefficients
in binary and ternary OBS, which can be used for the screening and
selection of the most appropriate system to be used in a separation
process.