Guidelines for descriptor assignments for the solvation parameter model by separation techniques | JoVE Visualize

Area of Science:

Physical Chemistry
Computational Chemistry

Background:

The solvation parameter model relies on six descriptors (E, S, A, B, V, L) to predict equilibrium properties in biphasic systems.
Traditionally, experimental determination of these descriptors, especially for solid compounds, involves extensive chromatographic, liquid-liquid partition, and solubility measurements.
Existing single-technique methods for descriptor assignment are resource-intensive and can be less efficient.

Purpose of the Study:

To develop and validate an efficient, multi-technique experimental design for accurate solvation descriptor assignment.
To minimize laboratory resource utilization while maintaining high accuracy in descriptor values.
To streamline the process of obtaining descriptors for neutral compounds, including those that are solid at room temperature.

Main Methods:

Employed an efficient experimental design utilizing the Solver method to simultaneously assign six solvation descriptors (E, S, A, B, V, L).
Integrated gas chromatography (GC) and reversed-phase liquid chromatography (RPLC) with liquid-liquid partition (LLP) measurements.
Required a total of 26 experimental measurements per compound, including retention factor measurements across temperature and solvent gradients, and partition coefficient determinations.

Main Results:

The multi-technique approach achieved high accuracy in descriptor assignments, with average absolute deviations (AAD) ranging from 0.013 (B) to 0.054 (E) compared to the WSU database.
Relative absolute average deviations (RAAD) were notably low, particularly for the L descriptor (0.84%) and B descriptor (5.1%).
Demonstrated successful application for 32 varied compounds, showing significant improvements over previous single-technique methods.

Conclusions:

The proposed streamlined, multi-technique approach efficiently and accurately assigns solvation descriptors, reducing experimental burden.
Modifications were implemented for compounds with variable hydrogen-bond basicity, maintaining experimental efficiency.
The method provides reliable descriptor values, with limitations noted for qualitative application of E and B/B° for solid compounds.