William E. Acree

MATHEMATICAL REPRESENTATION OF THERMODYNAMIC PROPERTIES: PART II. DERIVATION OF THE COMBINED NEARLY IDEAL BINARY SOLVENT(NIBS)/REDLICH-KISTER MATHEMATICAL REPRESENTATION FROM A TWO-BODY AND THREE-BODY INTERACTIONAL MIXING MODEL

Abstract A relatively simple two-body and three-body interactional mixing model is used to derive expressions for the mathematical representation of experimental solute solubilities and activity coefficients in binary solvent mixtures. The derived expressions are identical with those based upon the combined NIBS/Redlich-Kister model, and enable solute solubility/activity coefficient data to be expressed as a mole fraction average of measured solute properties in both pure solvents plus a term involving a power series expansion in solvent composition.

THERMODYNAMIC PROPERTIES OF NONELECTROLYTE SOLUTION. PART 4. ESTIMATION AND MATHEMATICAL REPRESENTATION OF SOLUTE ACTIVITY COEFFICIENTS AND SOLUBILITIES IN BINARY SOLVENTS USING THE NIBS AND MODIFIED WILSON EQUATIONS

Abstract The limitations and applications of the various nearly ideal binary solvent (NIBS) and Modified Wilson models for predicting the thermochemical properties of solutes dissolved in binary solvent mixtures are examined using published solute solubility and infinite dilution activity coefficient data for 72 systems. Expressions derived from the basic NIBS and extended NIBS models provide very reasonable predictions for anthracene, thianthrene and carbazole solubilities in systems containing both specific and non-specific interactions. For many of the systems considered, deviations between experimental and NIBS predictions are of the order of 6% or less. In comparison, the Modified Wilson equation grossly underpredicts the observed solubilities, with deviations for several of the carbazole systems being 40% or more. Both models can serve as a point-of-departure for the mathematical representation of experimental solubility data, and two possible descriptive forms are suggested.

Thermodynamic properties of organic compounds: enthalpy of fusion and melting point temperature compilation

Abstract Published enthalpies of fusion and melting point temperatures have been gathered from the chemical literature and are presented in tabular form according to increasing carbon and hydrogen atom numbers. References are also provided to indicate the literature sources consulted.

The solubility of gases and vapours in dry octan-1-ol at 298 K.

Ostwald solubility coefficients of 74 compounds in dry octan-1-ol at 298 K have been determined, and have been combined with literature values and additional values we have calculated from solubilities in dry octan-1-ol and vapour pressures to yield a total of 161 log L(OctOH) values at 298 K. These L(OctOH) values are identical to gas-to-dry octan-1-ol partition coefficients, often denoted as K(OA). Application of the solvation equation of Abraham to 124 values as a training set yielded a correlation equation with n = 124, S.D. = 0.125, r2 = 0.9970 and F = 7731. This equation was then used to predict 32 values of log L(OctOH) as a test set, giving a standard deviation, S.D. of 0.131, an average absolute deviation of 0.085 and an average deviation of -0.009 log units. The solvation equation for the combined 156 log L(OctOH) values was log L(OctOH) = -0.120 - 0.203R2 + 0.560pi2(H) + 3.560 sum(alpha2(H)) + 0.702 sum(beta2(H)) + 0.939 logL16, n =156, r2 = 0.9972, S.D. = 0.125, F = 10573, where, n is the number of data points (solutes), r the correlation coefficient, S.D. the standard deviation and F is the F-statistic. The independent variables are solute descriptors as follows: R2 is an excess molar refraction, pi2(H) the dipolarity/polarisability, sum(alpha2(H)) the overall or summation hydrogen-bond acidity, sum(beta2(H)) the overall or summation hydrogen-bond basicity and L16 is the Ostwald solubility coefficient on hexadecane at 298 K. The equation is consistent with similar equations for the solubility of gases and vapours into methanol, ethanol and propan-1-ol. It is suggested that the equation can be used to predict further values of log L(OctOH), for which the solute descriptors are known, to within 0.13 log units.

Mathematical correlation of naproxen solubilities in organic solvents with the abraham solvation parameter model

The Abraham solvation parameter model is used to calculate the numerical values of the solute descriptors for naproxen from experimental solubilities in organic solvents. The solute descriptors are denoted as follows: E is the solute excess molar refraction, V is McGowan volume of the solute, A and B are measures of the solute hydrogen-bond acidity and hydrogen-bond basicity, respectively, S is the solute dipolarity/polarizability descriptor and L is the logarithm of solute gas phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. We estimate E as 1.510 and calculate V as 1.7821, and then solve a total of 40 equations to yield S = 2.022, A = 0.600, B = 0.673 and L = 9.207. These descriptors reproduce the observed log solubility ratios to within a standard deviation of only 0.073 log units.

THERMOCHEMICAL INVESTIGATIONS OF ASSOCIATED SOLUTIONS: 3. EFFECT OF THE INERT COSOLVENT ON SOLUTE - SOLVENT ASSOCIATION CONSTANTS CALCULATED FROM SOLUBILITY MEASUNNENTS

Abstract Solubility are reported for caracole in binary solvent mixtures containing dibutyl ether with n-hexane, n-heptanes, n-octane, cyclopean, cyclostomes, methylcyclohexane and isooctane at 25°C. The results of these measurements are compared to solution models previously developed for solubility in systems containing specific solute-solvent interactions. A simple stoichiometric compellation model based primarily on specific solute-solvent interactions required two equilibrium constants to mathematically describe the experimental solubilitys in binary deputy ether mixtures. Calculated equilibrium constants in cyclostomes co solvent were significantly different from values for the isooctane co solvent system. In comparison, an expression derived by including nonspecific interaction contributions described the solubility data to within an average absolute deviation of 2% using a single carbazole-dibutyl ether association constant, which varied from KΦ = 22 for n-heptanes to KΦ = 30 for isooctane.

Solubility of Pyrene in Organic Nonelectrolyte Solvents. Comparison of Observed Versus Predicted Values Based Upon Mobile Order Theory

Abstract Experimental solubilities are reported at 26.0°C for pyrene dissolved in twenty different organic nonelectrolyte solvents containing ether-, ester-, chloro-, hydroxy-, and methyl-functional groups. Results of these measurements, combined with our previously published pyrene solubility data in benzene, dibutyl ether, 1,4-dichlorobutane, 1-propanol, 2-propanol and saturated hydrocarbons, are used to test the applications and limitations of expressions derived from Mobile Order theory. For the 30 solvents for which predictions could be made computations show that Mobile Order theory does provide fairly reasonable (though by no means perfect) estimates of the saturation mole fraction solubilities. Average absolute deviation between predicted and observed values is circa 79%. In comparison, the average absolute deviation increases significantly to 1380% when ideal solution behavior is assumed.

Fluorescence Emission Properties of Polycyclic Aromatic Compounds in Review

Abstract Fluorescence emission behavior of polycyclic aromatic hydrocarbons (PAHs), polycyclic aromatic nitrogen heterocycles (PANHs), polycyclic aromatic sulfur heterocycles (PASHs) and benzofluoranthenes dissolved in organic solvents of varying polarity is reviewed. Measured fluorescence properties are used to divide aromatic solutes into two categories, probe and nonprobe molecules, depending upon whether the molecules emission intensity ratios vary systematically with solvent polarity. Seventeen polycyclic aromatic hydrocarbon solute probes are identified and possible probe character versus molecular structure correlations are examined. Also discussed are instrumental and chemical artifacts associated with accurate determination of fluorescence emission intensities.

Abraham model correlations for solute transfer into tributyl phosphate from both water and the gas phase

Solubilities are reported for acenaphthene, fluoranthene, benzil, 9-fluorenone, trans-stilbene, phenothiazine, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-chlorobenzoic acid, 3-nitrobenzoic acid, 4-nitrobenzoic acid, 3,4-dichlorobenzoic acid, 3,5-dinitrobenzoic acid, 2-chloro-5-nitrobenzoic acid, and 4-chloro-3-nitrobenzoic acid dissolved in tributyl phosphate at 298 K. The experimental solubility data, combined with published infinite dilution activity coefficients and Henry’s law constants, are used to derive Abraham model correlations for predicting molar solubility ratios, gas-to-liquid partition coefficients, and water-to-liquid partition coefficients of organic solutes and inorganic gases dissolved in tributyl phosphate. The derived Abraham model equations describe the measured experimental values to within 0.15 log units or less.

Quantitative structure–activity relationship prediction of blood-to-brain partitioning behavior using support vector machine

In the present study a quantitative structure-activity relationship (QSAR) technique was developed to investigate the blood-to-brain barrier partitioning behavior (log BB) for various drugs and organic compounds. Important descriptors were selected by genetic algorithm-partial least square (GA-PLS) methods. Partial least squares (PLS) and support vector machine (SVM) methods were employed to construct linear and non-linear models, respectively. The results showed that, the log BB values calculated by SVM were in good agreement with the experimental data, and the performance of the SVM model was superior to the PLS model. The study provided a novel and effective method for predicting blood-to-brain barrier penetration of drugs, and disclosed that SVM can be used as a powerful chemometrics tool for QSAR studies.