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Abstract : Thermodynamic Modeling of Chiral Compounds Solubility Using Correlative and Predictive Models
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Abstract: Many intermolecular forces and parameters affect the solubility of a compound in a solvent. Various thermodynamic models are presented to predict these parameters and determine solid liquid equilibrium data. By selecting suitable thermodynamic model for solubility modeling, calculation error is reduced and the results will be closer to the experimental data. Herein, the ability of two predictive and two correlative models in solubility modeling of chiral compounds is investigated. Thus, solubility of pure and racemic forms of chiral Ketamine, Mandelic acid and 3-Chloromandelic acid is evaluated using UNIQUAC and NRTL models. The solubility modeling of pure and racemic forms of Ketamine in Ethanol is also determined by UNIFAC and NRTL-SAC models. There are good agreement between experimental data and results of NRTL and UNIQUAC models. Predictive NRTL-SAC model shows smaller deviation than UNIFAC in solubility determination of pure and racemic form of Ketamine. Keywords: Solubility, Chiral compounds, Thermodynamic modeling, NRTL-SAC, UNIFAC, UNIQUAC, NRTL.. Download Full Article |
Abstract : Free Unsolvated Formaldehyde in Solutions: Influence of Temperature, Solvent Permittiity, and Total Formaldehyde Concentration
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Abstract: A mechanism of the initiated nonbranched-chain process of forming 1,2-alkanediols and carbonyl compounds in alcohol–formaldehyde systems is suggested. The quasi-steady-state treatment is used to obtain kinetic equations that can describe the nonmonotonic (with a maximum) dependences of the formation rates of the products on the concentration of free unsolvated formaldehyde. The experimental concentration of the free unsolvated form of formaldehyde are given at the different temperatures, solvent permittivity and total concentrations of formaldehyde in water and alcohols. An empirical equation for calculating the free formaldehyde concentration in alcohol–formaldehyde (including water/ethanediol–formaldehyde) systems at various temperatures and total formaldehyde concentrations and an equation for evaluating solvent concentrations in these systems were derived. Keywords: Free formaldehyde, 1-hydroxyalkyl radical, formyl radical, equation. Download Full Article |
Abstract : Excess Molar Enthalpies of Mixtures of Acetylene Tetrachloride with Dimethylsulfoxide, Acetone, Acetonitrile and N-Dibutyl Ether at 303.15 K
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Abstract: The Excess molar enthalpies have been determined for binary liquid mixtures of acetylene tetrachloride (CHCl2CHCl2) (ATC) with dimethylsulfoxide, acetone, acetonitrile and n-dibutyl ether at the temperature 303.15 K by microcalorimetry. The excess molar enthalpies are negative for all the mixtures over the whole composition range. The results were fitted with the Redlich-Kister equation by means of the least square method. The values of HE decrease in the order: Dimethylsulphoxide > acetone>acetonitrile > dibutyl ether. The same decreasing trend was observed for calculated hydrogen bond energies of these systems. These results indicate the existence of specific interactions between all these components. Keywords: Excess molar enthalpy, acetylene tetrachloride, acetone, microcalorimetry, hydrogen bonding. Download Full Article |
Abstract : Benzothiazole-Based Bis-azo Cationic Fluorescent Dyes with Extended Conjugated Systems: Synthesis and Properties
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Abstract: Sixteen novel 2-aminobenzothiazole based dichromophoric cationic azo dyes were synthesized and their photophysical properties studied. The colors of the synthesized azo dyes were violet to blue with high molecular extinction coefficient ranged between 2.6 - 4.7× 104 (M-1.cm-1). All of the dyes showed unique fluorescence emission at a broad range of 409–494 nm. The absorption and emission spectral changes of selected dyes were also analyzed in solvents with different polarity. Furthermore, the antibacterial activities of the dyes were evaluated against gram positive and negative bacteria including S. aureus, S. epidermidis, E. coli, and P. aeruginosa and different concentrations of dyes showed an anti-gram positive bacterial activity. Keywords: Benzothiazole, Azo Dyes, Fluorescence, Cationic dye, Antibacterial, Solvatochromism. Download Full Article |
