Abraham model solute descriptors are determined for vanillin and five select derivatives (o-vanillin, isovanillin, vanillic acid, vanillyl alcohol and ethylvanillin) based on experimental solubility and partition coefficient data that we were able to find in the published literature. The solute descriptor values reported in the current communication back-calculate the observed experimental data to within standard errors of 0.12 log units (or less). The calculated solute descriptors can be used to predict the solubility of the vanillin and the five select derivatives in additional organic mono-solvents and binary aqueous-ethanol solvent mixtures using published Abraham model correlations.

Abraham model solute descriptors have been determined for nisoldipine, nizatidine, loratadine, zonisamide, oxaprozin, rebamipide, domperidone, temozolomide, 'florfenicol', florfenicol A, dapsone, chrysin, benorilate, β-lapachone, and Ipriflavone based on published partition coefficients, molar solubilities and gas chromatographic retention indices. The calculated solute descriptors, combined with our previously published Abraham model correlations, are used to predict several important physicochemical and biological properties, such as air-water, air-blood, air-lung, air-fat, air-skin, water-lipid, water-membrane and water-skin partition coefficients, as well as permeation from water through skin.

ABSTRACT Experimental water-to-methyl ethyl ketone partition coefficients have been determined for 34 different organic solutes at ambient room temperature based on gas–liquid chromatographic measurements. Updated Abraham model correlations were determined for describing solute transfer into methyl ethyl ketone by combining the measured partition coefficient data determined in the present study with published experimental values taken from chemical and engineering literature. Experimental data for 48 compounds were used in determining the revised Abraham model correlations. The revised mathematical correlations were determined to back-calculate the observed partition coefficient data to within an overall average standard deviation of 0.17 log units or less. The partitioning characteristics of the water-to-methyl ethyl ketone system are compared to the characteristics of two other biphasic water-to-ketone partitioning systems.

We present a group contribution method (SoluteGC) and a machine learning model (SoluteML) to predict the Abraham solute parameters, as well as a machine learning model (DirectML) to predict solvation free energy and enthalpy at 298 K. The proposed group contribution method uses atom-centered functional groups with corrections for ring and polycyclic strain whilst the machine learning models adopt a directed message passing neural network. The solute parameters predicted from SoluteGC and SoluteML are used to calculate solvation energy and enthalpy via linear free energy relationships. Extensive data sets containing 8366 solute parameters, 20253 solvation free energies, and 6322 solvation enthalpies are compiled in this work to train the models. The three models are each evaluated on the same test sets using both random and substructure-based solute splits for solvation energy and enthalpy predictions. The results show that the DirectML model is superior to the SoluteML and SoluteGC models for both predictions and can provide accuracy comparable to that of advanced quantum chemistry methods. Yet, even though the DirectML model performs better in general, all three models are useful for various purposes. Uncertain predicted values can be identified by comparing the 3 models, and when the 3 models are combined together, they can provide even more accurate predictions than any one of them individually. Finally, we present our compiled solute parameter, solvation energy, and solvation enthalpy databases (SoluteDB, dGsolvDBx, dHsolvDB) and provide public access to our final prediction models through a simple web-based tool, software package, and source code.

Experimental water-to-methyl isobutyl ketone partition coefficients have been determined for 27 different organic solutes based on gas chromatographic measurements. Updated Abraham model correlations were determined for describing solute transfer into methyl isobutyl ketone by combining the measured partition coefficient data determined in the present study with published experimental values taken from chemical and engineering literature. One hundred nineteen compounds were used in determining the revised Abraham model correlations. After calculations, the revised mathematical correlations were found to match the experimental data to within an overall average standard deviation of 0.21 log units.

A search of the published chemical and engineering literature found enthalpy of solution data for an additional 71, 39 and 46 organic compounds dissolved in heptane, cyclohexane and N,N-dimethylformamide, respectively. The newly retrieved enthalpy of solution data was converted to enthalpy of solvation values, Delta H-solv, using standard thermodynamic relationships. Updated Abraham model correlations were derived for describing gas-to-heptane, gas-to-cyclohexane and gas-to-N,N-dimethylformamide enthalpies of solvation by combining the additional values to our existing heptane, cyclohexane and N,N-dimethylformamide Delta H-solv databases. The updated Abraham model correlations for heptane, cyclohexane and N,N-dimethylformamide described the observed Delta H-solv values to within overall standard deviations of less than 3 kJ/mole.

Literature data on solubilities of adamantane in organic solvents have been used to obtain properties, or descriptors, of adamantane. There is much less data on substituted adamantanes but we have been able to obtain descriptors for some 40 substituted adamantanes. These descriptors can then be used to estimate a wide range of physicochemical, environmental and other properties of the adamantanes. For the first time, the water-solvent partition coefficient and the gas-solvent partition coefficient into a large range of solvents, can be estimated, the latter being equivalent to Henry's Law constants. A variety of other important properties can also be estimated. These include vapor pressures, enthalpies of vaporization and sublimation, partitions from air and from blood into biological tissues, and skin permeability from water. The descriptors themselves are not exceptional. Adamantane itself has a rather low dipolarity, zero hydrogen bond acidity and a very low hydrogen bond basicity, in common with other multicyclic aliphatic compounds. These lead to adamantane being a very hydrophobic compound, as is evident from our estimated water-octanol partition coefficient.

Experimental solubility data are reported for anthracene, biphenyl, benzil, benzoin, 1-chloroanthraquinone, phenothiazine, pyrene, salicylamide, thioxanthen-9-one, xanthene, benzoic acid, 4-tert-butylbenzoic acid, 4-chloro-3-nitrobenzoic acid, 3,4-dichlorobenzoic acid, 3,4-dimethoxybenzoic acid, 2-hydroxybenzoic acid, 4-methoxybenzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 3-methyl-4-nitrobenzoic acid, 4-nitrobenzoic acid and 3,4,5-trimethoxybenzoic acid dissolved in dimethyl carbonate at 298.15 K. Abraham model correlations are derived for solute transfer into dimethyl carbonate by combining our measured solubility data with published activity coefficient and solubility data retrieved from the published chemical and engineering literature. The derived Abraham model correlations back-calculate the 52 experimental molar solubilities and infinite dilution activity coefficients to within 0.13 log units.

Abraham model correlations are derived for describing gas-to-ionic liquid and water-to-ionic liquid partition coefficients from published experimental data for solutes dissolved in both N-ethyl-N-methylmorpholinium bis(trifluoromethylsulfonyl)imide and N-octyl-N-methylmorpholinium bis(trifluoromethylsulfonyl)imide. Derived Abraham model correlations describe the observed partition coefficient data to within 0.14 log units. As part of the current study, we also determined Abraham model ion-specific equation coefficients for both N-ethyl-N-methylmorpholinium and N-octyl-N-methylmorpholinium cations.

The LFER model of Abraham is applied to the retention of the neutral and ionic forms of 94 solutes in a C18 column and 40% v/v acetonitrile/water mobile phase. The results show that polarizability and cavity formation interactions increase retention, whereas dipole and hydrogen bonding interactions favours partition to the mobile phase and thus, they decrease retention. The coefficients of the ionic descriptors measure the effect of the electrostatic interactions and their contribution to partition of the cation or anion between the two mobile and stationary chromatographic phases.A new LFER model for application to the retention of partially dissociated acids and bases is derived averaging the descriptors of the neutral and ionic forms according to their degrees of ionization in the mobile phase. This new LFER model is satisfactorily compared to other literature modified Abraham models for a set of 498 retention data of partially dissociated acids and bases.All tested models require the calculation of the ionization degrees of the compounds at the measuring pH. Calculation of the ionization degrees in the chromatographic mobile phase (i.e. from pH and pKa in the eluent) give good correlations for all tested models. However, estimation of these ionization degrees from pH – pKa data in pure water gives biased estimations of the retention of the partially ionized solutes.

Abraham model solute descriptors are calculated for several environmentally important fluorotelomer alcohols from published partition coefficient and solubility data. The various descriptors all show a gradual trend from 1:2FTOH to 8:2FTOH. The maximum deviation from self-consistent values is 0.19 log units in the calculations on vapour pressure (concentration in air) and solubility in water (concentration in water).

Abraham model L solute descriptors have been determined for an additional 33 linear C 7 -C 14 alkynes based on published gas chromatographic retention indices for solutes eluted from capillary columns coated with squalane and apiezon L stationary phases. Standard molar enthalpies of vaporization and sublimation at 298 K are calculated for the 33 linear alkynes using the reported solute descriptors and our recently published Abraham model correlations. Calculated vaporization enthalpies derived from the Abraham model compare very favourably with values based on a popular atom-group additivity model.

We have used literature values for the solubility of vitamin K3 in organic solvents to obtain Abraham descriptors for vitamin K3. Although these descriptors themselves are not exceptional in any way, when combined with equations that we have already set out, they lead to the prediction of important properties of vitamin K3. These include the vapor pressure and heat of sublimation (necessary for the analysis of data on the concentration of vitamin K3 in ambient air), and the partitions air-water, air-blood, air-lung, air-fat, air-skin, water-lipid, water-membrane, water-skin, as well as permeation from water through skin. Values of the partitions into biological phases are all quite large by comparison to those for organic compounds in general.

We have obtained properties (or descriptors) of the transition states in the solvolysis of tert-butyl chloride, bromide and iodide. We show that all three transition states, in both protic and in aprotic solvents, are highly dipolar and are strong hydrogen bond acids and strong hydrogen bond bases, except for the tert-butyl iodide transition state in aprotic solvents, which has a rather low hydrogen bond acidity. Thus, the transition states are stabilized by solvents that are hydrogen bond bases (nucleophiles) and are hydrogen bond acids (electrophiles). We show also that the partition of the transition states between water and solvents is aided by both nucleophilic and electrophilic solvents and conclude that the rate of solvolysis of the three halides is increased by both nucleophilic and electrophilic solvents.

Literature solubilities and NMR and IR studies have been used to obtain properties or descriptors of edaravone. These show that edaravone has a significant hydrogen bond acidity so that it must exist in solution partly as the OH and NH forms, as found by Freyer et al. Descriptors have been assigned to the keto form which has a low hydrogen bond acidity, and which is the dominant form in nonpolar solvents. Physicochemical properties of the keto form can be been calculated such as solubilities in nonpolar solvents, partition coefficients from water to nonpolar solvents, and partition coefficients from air to biological phases.

Experimental solubilities have been determined for 1-chloroanthraquinone, anthracene, biphenyl, pyrene, benzil, benzoic acid, acetylsalicylic acid, 4-tert-butylbenzoic acid, 3,4-dichlorobenzoic acid, 2-chloro-5-nitrobenzoic acid, 4-chloro-3-nitrobenzoic acid, 2-methoxybenzoic acid, 4-methoxybenzoic acid, 3,4-dimethoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methyl-3-nitrobenzoic acid, 4-nitrobenzoic acid, benzoin, salicylamide, thioxanthen-9-one, 1,4-dichloro-2-nitrobenzene and phenothiazine dissolved in diethyl carbonate at 298.15 K. Results of our experimental measurements, combined with published solubility and activity coefficient data, have been used to derive Abraham model correlations for describing solute transfer into diethyl carbonate. The derived mathematical correlations back-calculate the observed experimental data to within an overall standard deviation of 0.13 log units.

Experimental solubilities have been measured at 298.15 K for benzil, biphenyl, pyrene, fluoranthene, acenaphthene, xanthene, fluorene, 1,2,4,5-tetramethylbenzene, 4-tert-butylbenzoic acid, benzoic acid, 4-chloro-3-nitrobenzoic acid, 4-methoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, 3-methyl-4-nitrobenzoic acid, 4-aminobenzoic acid, diphenyl sulphone, 2-ethylanthraquinone, thioxanthen-9-one, thianthrene, o-acetoacetanisidide, sorbic acid, 1,4-dichloro-2-nitrobenzene, 1,4-dibromobenzene, salicylamide, benzoin and trans-stilbene. Results of experimental measurements were combined with published solubility data taken from the published literature to derive Abraham model correlations for transfer of solutes into 2-methyl-1-butanol. The reported Abraham model correlations describe the observed solute transfer coefficients to within an overall average standard deviation of approximately 0.08 log units.

Abraham model correlations are reported for describing the logarithms of water-to-plant cuticle partition coefficients and logarithms of air-to-plant partition coefficients based on experimental values retrieved from the published chemical and environmental literature for 24 different plant species. Data sets containing more than 200 experimental partition coefficients were used in determining each correlation equation. The derived correlations back-calculated the experimental data to within a standard deviation of 0.23 log units.

We have used a variety of physicochemical systems, including water-solvent partitions, solubility in non-aqueous solvents, and HPLC and gas chromatographic retentions to obtain descriptors for nitro compounds and high energy compounds. These descriptors can then be used to predict a wide range of other physicochemical properties as well as thermodynamic and environmental properties. We illustrate the latter by predictions of the vapor pressure of sublimation, the enthalpy of sublimation and the heat capacity of sublimation at 298.15 K, and predictions of human skin permeability from water. With respect to the obtained descriptors, the most startling finding is that cyclic high energy compounds, with no 'active' hydrogen atom, have a substantial 'hydrogen bond' acidity. We suggest that this is due to electron-deficient ring systems that act as Lewis acids.