Joyce R. Powell

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.

Thermochemical Investigations of Hydrogen-Bonded Solutions. Part 9. Comparison of Mobile Order Theory and the Kretschmer-Wiebe Association Model for Predicting Pyrene Solubilities in Binary Alcohol + Alcohol Solvent Mixtures

A relatively simple expression is developed for predicting the solubility of an inert crystalline solute in binary alcohol + alcohol solvent mixtures based upon the Kretschmer-Wiebe association model. The predictive accuracy of the newly-derived expression is compared to equation(s) derived previously from Mobile Order theory. Computations show that both models accurately describe the solubility behavior of pyrene in the 24 binary solvent systems studied. Average absolute deviations between observed and predicted values were 2.0% and 2.2% for the Kretschmer-Wiebe and Mobile Order predictive equations, respectively.

Prediction of anthracene solubility in alcohol + alkane solvent mixtures using binary alcohol + alkane VLE data. Comparison of Kretschmer-Wiebe and mobile order models

Abstract The abilities of two association models to predict anthracene solubilities in a number of binary alkane + alcohol solvent mixtures are compared. For each alkane + alcohol system, parameters in the Kretschmer-Wiebe and mobile order models were obtained from binary vapor-liquid equilibrium data. These parameters were then used, along with measured solubilities of anthracene in the pure alcohol and pure alkane, to predict solubilities of anthracene in the alkane + alcohol mixtures. To increase the number of systems available for analysis, new solubility data were measured at 298.15 K for anthracene in mixtures of n-heptane with 1-pentanol, 2-pentanol, and 2-methyl-2-butanol and for mixtures of n-hexane with 1-pentanol. New total pressure data at 303.15 K were obtained for n-heptane + 1-butanol and n-heptane + 2-butanol. Combining literature data with those reported here results in twenty binary alkane + alcohol systems for which both VLE data and anthracene solubilities are available. Upon fitting to the VLE data, the Kretschmer-Wiebe and mobile order models were found to represent equilibrium pressures with root mean square deviations of 0.13 and 0.19 kPa, respectively. Solubilities of anthracene in alkane + alcohol mixtures were predicted with average deviations of 2.8% and 4.7%, respectively.

Discovery of MK-3168: A PET Tracer for Imaging Brain Fatty Acid Amide Hydrolase.

We report herein the discovery of a fatty acid amide hydrolase (FAAH) positron emission tomography (PET) tracer. Starting from a pyrazole lead, medicinal chemistry efforts directed toward reducing lipophilicity led to the synthesis of a series of imidazole analogues. Compound 6 was chosen for further profiling due to its appropriate physical chemical properties and excellent FAAH inhibition potency across species. [(11)C]-6 (MK-3168) exhibited good brain uptake and FAAH-specific signal in rhesus monkeys and is a suitable PET tracer for imaging FAAH in the brain.

Polycyclic aromatic hydrocarbon solute probes Part XII: Dissimilar fluorescence excitation/emission behavior between alkylpyrene and alkylcoronene derivatives and the parent pah molecule

Abstract Fluorescence excitation and emission behavior are reported for methylcoronene, 1,2-dimethylcoronene, 2-isopropyl-pyrene, 4-isopropylpyrene, 2,4,7,10-tetraisopropylpyrene, 1,3,6,8-tetraisopropylpyrene, 1,3,5,7,9-pentaisopropylpyrene, 2,7-di- tert -butylpyrene, 2,7-di-(dimethylpropyl)pyrene, 1,3,6,8-tetracyclopentylpyrene and 1,3,6,8-tetracyclohexylpyrene dissolved in various organic solvents of varying solvent polarity. Experimental results are used to test a potential screening method for determining whether a given alkyl-substituted polycyclic aromatic hydrocarbon (PAH) solute is likely to exhibit probe character, as evidenced by a systematic variation in the ratios of the fluorescence intensities of select emission bands with solvent polarity. Of the eleven solutes studied, only 4-isopropylpyrene, methylcoronene and 1,2-dimethylcoronene showed useful solvent polarity probe character. 1,3,6,8-Tetraisopropylpyrene, 1,3,5,7,9-pentaisopropylpyrene, 1,3,6,8-tetracyclohexylpyrene and 1,3,6,8-tetracyclopentylpyrene exhibited slight probe behavior; however, the dynamic ranges covered in emission intensity ratios were believed to be too small for many practical applications when compared against the experimental uncertainty associated with the measured values.

Thermodynamics of mobile order theory: comparison of experimental and predicted anthracene and pyrene solubilities in binary alkane+alcohol solvent mixtures

Abstract Experimental solubilities are reported for pyrene in ten binary alkane+alcohol solvent mixtures containing either 1-butanol or 2-methyl-1-propanol with hexane, heptane, octane, cyclohexane and methylcyclohexane. Results of these measurements, along with published anthracene and pyrene solubility data, are used to test predictive expressions based upon the mobile order theory. For the 59 systems studied, the best predictive equation was found to predict the observed solubility data to within an overall average deviation of about 3% using numerical values of 125 cm 3 mol −1 and 175 cm 3 mol −1 for the anthracene–alcohol and pyrene–alcohol stability constants, respectively. Alcohol self-association constants and binary interaction parameters were obtained by regressing vapor–liquid equilibria (VLE) data for alkane+alcohol mixtures.

Solubility of anthracene in binary alcohol + 1-pentanol solvent mixtures at 25°C: Comparison of expressions derived from Mobile Order theory and the Kretschmer-Wiebe association model

A relatively simple expression is developed for predicting the solubility of an inert crystalline solute in binary alcohol + alcohol solvent mixtures based upon the Kretschmer-Wiebe association model. The predictive accuracy of the newlyderived expression is compared to equation(s) derived previously from Mobile Order theory using experimental anthracene solubilities in seven binary alcohol + 1-pentanol solvent mixtures at 25°C, which were measured as part of the present investigation. Computations show that both models accurately describe the solubility behavior of anthracene in the binary solvent systems studied. Average absolute deviations between observed and predicted values were 0.9% and 1.4% for the Kretschmer-Wiebe and Mobile Order predictive equations, respectively.

Solubility of thianthrene in organic nonelectrolyte solvents : Comparison of observed versus predicted values based upon mobile order theory

Abstract Experimental solubilities are reported at 25.0°C for thianthrene dissolved in twenty-one different organic nonelectrolyte solvents containing ether-, hydroxy-, and t-butyl-functional groups. Results of these measurements combined, with our previously published thianthrene solubility data in n-hexane, n-heptane, n-octanc, cyclohexane, methylcyc-lohexane, 2, 2, 4-trimethylpentane and cyclooctane, are used to test the applications and limitations of expressions derived from Mobile Order theory. For the 20 solvents for which predictions could be made computations show that Mobile Order theory does provide fairly reasonable (although by no means perfect) estimates of the saturation mole fraction solubilities. Average absolute deviation between predicted and observed values is circa 58%. In comparison, the average absolute deviation increases significantly to 1,940% when ideal solution behavior is assumed.

Thermochemical investigations of hydrogen-bonded solutions. Part 8. Comparison of mobile order theory and the Kretschmer-Wiebe association model for predicting anthracene solubilities in binary alcohol + alcohol solvent mixtures

Abstract A relatively simple expression is developed for predicting the solubility of an inert crystalline solute in binary alcohol + alcohol solvent mixtures based upon the Kretschmer-Wiebe association model. The predictive accuracy of the newly-derived expression is compared to equation(s) derived previously from Mobile Order theory. Computations show that both models accurately describe the solubility behavior of anthracene in the 28 binary solvent systems studied. Average absolute deviations between observed and predicted values were 1.4% and 1.7% for the Kretschmer-Wiebe and Mobile Order predictive equations, respectively.

Thermochemical investigations of hydrogen-bonded solutions. Part 11. Expressions for predicting anthracene solubilities in alcohol + alkoxyalcohol mixtures based on Mobile Order theory

Experimental solubilities are reported for anthracene dissolved in eight binary mixtures containing 2-ethoxyethanol with 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 1-pentanol, 3-methyl-1-butanol and 1-octanol, and also in binary 1-pentanol+2-methoxyethanol and 2-methyl-1-propanol+2-propoxyethanol solvent systems at 25°C. Results of these measurements, combined with previously reported anthracene solubility data in 22 different alcohol +2-alkoxyethanol (2-methoxyethanol, 2-propoxyethanol and 2-butoxyethanol) solvent mixtures, are used to test the limitations and applications of expressions derived from Mobile Order theory. The first predictive expression assumes only formation of homogeneous self-associated hydrogen-bonded species, whereas the second equation includes additional terms to account for heterogeneous complex formation between the dissolved alcohol and 2-alkoxyethanol solvent molecules. Both equations predict the observed anthracene solubilities to within an average absolute deviation of about 3%.