Descriptors for terpene esters from chromatographic and partition measurements: Estimation of human odor detection thresholds

We have used gas chromatographic retention data together with other data to obtain Abraham descriptors for 30 terpene esters. These include the air-water partition coefficient, as log Kw, for which no experimental values are available for any terpene ester. The other descriptors are the ester dipolarity, S, the hydrogen bond basicity, B, (the ester hydrogen bond acidity is zero for the esters studied), and L the logarithm of the air-hexadecane partition coefficient. Both S and B are larger than those for simple aliphatic esters, as expected from the terpene ester structures that include ring systems and ethylenic double bonds. These descriptors can then be used to obtain a large number of physicochemical and environmental properties of terpene esters. We have analyzed experimental results on human odor detection thresholds and have constructed another equation for the calculation of these thresholds, to go with a previous equation that we have reported. Then the descriptors for terpene esters can be used to estimate the important odor detection thresholds

Selection of Ionic Liquid Solvents for Chemical Separations Based on the Abraham Model

Book chapter on the selection of ionic liquid solvents for chemical separations based on the Abraham model

Prediction of Partition Coefficients and Permeability of Drug Molecules in Biological Systems with Abraham Model Solute Descriptors Derived from Measured Solubilities and Water-to-Organic Solvent Partition Coefficients

Book chapter on the prediction of partition coefficients and permeability of drug molecules in biological systems with Abraham model solute descriptors derived from measured solubilities and water-to-organic solvent partition coefficients

Equations for the Correlation and Prediction of Partition Coefcients of Neutral Molecules and Ionic Species in the Water-Isopropanol Solvent System

We use literature data on solubilities of 46 compounds in the water-isopropanol (IPA) system to obtain the corresponding partition coefficients, P, for transfer from water to water- IPA mixtures. We have then used our previously constructed linear free energy equation to obtain equations that correlate log10 P at water-IPA intervals across the entire water-IPA system. These equations can then be used to predict partition coefficients and solubilities of further compounds in the water-IPA systems at 298 K. The coefficients in our linear free energy equation encode information on the physicochemical properties of the water- IPA mixtures. We show that the hydrogen bond basicity of the water-IPA mixtures only increases slightly from water to IPA, but that the hydrogen bond acidity of the mixtures decreases markedly from water to IPA in a smooth continuous manner. We have also used data on ions and on ionic species to set out equations for the estimation of their partition coefficients from water to water-IPA mixtures. We find that for partition from water to IPA itself, log10 P = − 1.81 for H+

Air to Blood Distribution of Volatile Organic Compounds: A Linear Free Energy Analysis

Partition coefficients, K blood , for volatile organic compounds from air to blood have been collected for 155 compounds (air to human blood) and 127 compounds (air to rat blood). For 86 common compounds, the average error, AE, between the two sets of log K blood values is 0.12 log units, somewhat smaller than our estimated interlaboratory average SD value of around 0.16 log units. We conclude that with regard to experimental errors, there is no significant difference between K blood values in human blood and in rat blood. There are 196 compounds for which either or both K blood (human) and K blood (rat) are available. A training set of 98 compounds could be fitted with the Abraham solvation parameters with R 2 ) 0.933 and SD ) 0.34 log units. The training equation was then used to predict the test set of values with AE ) 0.04 log units, SD ) 0.33 log units, and an average absolute error, AAE, of 0.25 log units. A second training and test set yielded similar values: AE ) 0.01, SD ) 0.39, and AAE ) 0.29 log units. It is concluded that it is possible to construct an equation capable of predicting further values of log K blood to around 0.30 log units. Because the descriptors used in the correlation equations can be predicted from structure, it is now possible to predict log K blood for any chemical structure

MATHEMATICAL CORRELATIONS FOR DESCRIBING ENTHALPIES OF SOLVATION OF ORGANIC VAPORS AND GASEOUS SOLUTES INTO IONIC LIQUID SOLVENTS

KEY WORDS AND PHRASES: Enthalpy of solvation, ionic liquid, linear solvation energy relationship, solute descriptor

Predicting Abraham model solvent coefficients

Abstract Background: The Abraham general solvation model can be used in a broad set of scenarios involving partitioning and solubility, yet is limited to a set of solvents with measured Abraham coefficients. Here we extend the range of applicability of Abraham's model by creating open models that can be used to predict the solvent coefficients for all organic solvents. Results: We created open random forest models for the solvent coefficients e, s, a, b, and v that had out-of-bag