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W E Acree

Publications and source records attributed to W E Acree.

12 recordsLinked to original sources
PubMed1989

Polycyclic aromatic hydrocarbon solute probes. Part II. Effect of solvent polarity on the fluorescence emission fine structures of coronene derivatives.

The fluorescence properties of coronene (Co), benzo[a]coronene (BCo), naphtho[2,3-a]coronene (NCo), dibenzo[a,j]coronene (DCo), naphtho[1,2,3,4-ghi]perylene, benzo[pqr]naphtho[8,1,2-bcd]perylene and dibenzo[cd,lm]perylene dissolved in solvents of varying polarity are reported. Measurements indicated that the emission intensities of the four coronene derivatives depended on solvent polarity. The Co, BCo and NCo scales have been defined as the ratio of the fluorescence intensities of bands I and III of the vibronic spectra. Band III of dibenzo[a,j]coronene was not clearly identifiable in all the solvents studied, and the DCo scale was therefore defined as the intensity ratio of band I and IV. Emission intensity ratios of the three perylene derivatives remained nearly constant, irrespective of solvent polarity.

Chemical Phenomena↗
PubMed1987

Thermochemical investigations of associated solutions: 4. Calculation of carbazole-dibutyl ether association constants from measured solubility in binary solvent mixtures.

Experimental solubilities are reported for anthracene and carbazole in binary dibutyl ether plus n-hexadecane and dibutyl ether plus squalane solvent mixtures at 25 degrees C. Results of these measurements, used in conjunction with the extended nearly ideal binary solvent (NIBS) model, enabled calculation of the carbazole-dibutyl ether association constant. The numerical value obtained was independent of the hydrocarbon cosolvent, and compared favorably with previously reported values based on carbazole solubilities in solvent mixtures containing much smaller alkane cosolvents.

Carbazoles↗
PubMed1987

Thermochemical investigations of associated solutions: 5. Calculation of solute-solvent equilibrium constants from solubility in mixtures containing two complexing solvents.

Solubilities are reported for carbazole in binary dibutyl ether plus 1-chlorohexane mixtures at 25 degrees C. Results of these measurements are compared with solution models developed for solubility in systems containing specific solute-solvent interactions. A simple stoichiometric complexation model based on a 1:1 carbazole:dibutyl ether complex could describe the measured solubility to within an average absolute deviation of 1.7%. The calculated equilibrium constant, though, was about one-half of values previously determined from carbazole solubilities in several binary dibutyl ether plus alkane mixtures. A more sophisticated solution model, derived by assuming both 1:1 carbazole: dibutyl ether and carbazole:chlorohexane complexes, could describe the solubilities to within 2.4%. This latter model enables the carbazole-chlorohexane association constant to be calculated from experimental carbazole solubilities and a priori knowledge of the carbazole-dibutyl ether equilibrium constant.

Carbazoles↗
PubMed1983

Solubility in binary solvent systems III: predictive expressions based on molecular surface areas.

The nearly ideal binary solvent model, which has led to successful predictive equations for the partial molar Gibbs free energy of the solute in binary solvent mixtures, was extended to include molecular surface areas as weighting factors. Two additional expressions were derived and compared to previously developed equations (based on molar volumes as weighting factors) for their ability to predict anthracene and naphthalene solubilities in mixed solvents from measurements in the pure solvents. The most successful equation in terms of goodness of fit involved a surface fraction average of the excess Gibbs free energy relative to Raoult's law and predicted experimental solubilities in 25 systems with an average deviation of 1.7% and a maximum deviation of 7.5%. Two expressions approximating weighting factors with molar volumes provided accurate predictions in many of the systems studied but failed in their ability to predict anthracene solubilities in solvent mixtures containing benzene.

Chemical Phenomena↗
PubMed1983

Thermochemical investigations of associated solutions: calculation of solute--solvent equilibrium constants from solubility measurements.

A simple solution model that has lead to successful predictive equations for the partial molar excess properties of a solute in simple binary solvent mixtures containing only nonspecific interactions is extended to include association between the solute and one of the solvent components. An expression is derived and tested for its ability to describe anthracene solubilities in binary solvent mixtures containing benzene. The best description of the experimental solubilities requires the formation of a 1:1 anthracene-benzene complex, with a molarity-based equilibrium constant of KcAC approximately equal to 0.107 M-1. In comparison, a stoichiometric complexation model which attributes all solubility enhancement to the formation of anthracene-benzene complexes requires a somewhat larger equilibrium constant (KcAC approximately equal to 0.228 M-1) to describe the solubility behavior of anthracene in the benzene-n-heptane system. The results of these calculations illustrate that the determination of solute-solvent equilibrium constants from solubility data depends on the theoretical model used and the manner in which nonspecific interactions are incorporated into the model.

Chemical Phenomena↗
PubMed1982

Solubility in binary solvent systems I: Specific versus nonspecific interactions.

Solubilities are reported for benzil in carbon tetrachloride-alkane (isooctane, n-octane, cyclooctane) systems at 25 degrees and in similar binary mixtures containing cyclohexane plus alkane. The results of these measurements are compared to solution models previously developed for solubility in systems containing specific solute-solvent interactions and to models for purely nonspecific interactions. A stoichiometric complexation model based primarily on specific solute-solvent interactions requires several equilibrium constants to mathematically describe the experimental solubilities in binary carbon tetrachloride mixtures. However, there was no direct experimental evidence to suggest complexation between benzil and carbon tetrachloride. In comparison, expressions derived from the Nearly Ideal Binary Solvent (NIBS) model for nonspecific interactions predict experimental solubilities with a maximum deviation of 5% and an overall deviation of 1.0%. The success of the NIBS approach for this system is significant because the mole fraction solubility of benzil changes by a factor of 14 in the carbon tetrachloride-isooctane system.

Alkanes↗
PubMed1981

Thermochemical investigations of nearly ideal binary solvents. VII: Monomer and dimer models for solubility of benzoic acid in simple binary and ternary solvents.

Solubilities are reported for benzoic acid at 25.0 degrees in binary mixtures of carbon tetrachloride with cyclohexane, n-hexane, or n-heptane and of cyclohexane with n-hexane or n-heptane and in ternary mixtures of carbon tetrachloride-cyclohexane-n-hexane and carbon tetrachloride-cyclohexane-n-heptane. Solubilities also are reported for benzoic acid in some binary solvents at 30.0 degrees and for m-toluic acid in binary mixtures of cyclohexane and n-hexane at 25.0 degrees. The results are compared to the predictions of equations developed previously for solubility in systems of purely nonspecific interactions, with the benzoic acids considered as either monomeric or dimeric molecules in solution. The dimer model gave more accurate predictions, with a maximum deviation of 4.4% between observed and predicted solubilities in all systems studied. Solubility maxima were predicted and observed for benzoic and m-toluic acids in cyclohexane-n-hexane and for benzoic acid in cyclohexane-n-heptane. The application of these solubility relationships to liquid-liquid partition coefficients is discussed.

Benzoates↗