Addition and update of compounds for the 2025 Wayne state university compound descriptor database for use with the...

The solvation parameter model describes the transfer properties of neutral compounds in biphasic systems using six compound descriptors defined as excess molar refraction, E, dipolarity/polarizability, S, effective hydrogen-bond acidity, A, effective hydrogen-bond basicity, B, McGowan's characteristic volume, V, and the gas-liquid partition constant at 25 °C for n-hexadecane as solvent. The V descriptor and E descriptor for liquids at 20 °C can be calculated from structure and a refractive index value. The other descriptors are experimental quantities typically determined by chromatographic, liquid-liquid partition, or solubility measurements. In this study, partition constants from multiple sources in up to thirty-five gas-solvent and sixteen water-solvent partition systems are used to assign descriptors for an additional one hundred and sixteen compounds unavailable in the WSU-2025 compound descriptor database. These include five organosulfur compounds, six dialklyamines, seven branched alkanes, thirteen alkenes, and twenty-one carboxylic acids as new family groups. Updated descriptors are provided for thirteen compounds from the WSU-2025 descriptor database originally estimated from either small experimental datasets or with only a partial set of descriptor values. Descriptor quality was verified by the recalculation of the descriptors for nineteen compounds using only experimental partition constants and calibration models identified in this study. These are compared with the descriptor values in the WSU-2025 descriptor database taken as reference values. The average deviation was used to show that there is no significant bias for the descriptors assigned from partition constants alone with a typical error (absolute average deviation) of 0.083 for E, 0.040 for S, 0.038 for A, 0.015 for B, and 0.068 for L, respectively, corresponding to 5.5% for E, 1.6 % for S, 9.5 % for A, 3.9 % for B, and 1.5 % for L. The descriptors are suitable for use as secondary reference values for modeling environmental, biological and chemical partition systems. It is suggested that the WSU-2025 database be used as the primary source of calibration compounds for characterizing chromatographic systems related to the larger experimental uncertainty in partition constants compared with chromatographic retention factors.