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Thermochemistry of heteroatomic compounds

VII. Enthalpies of solution, vaporization and solvation of three-coordinated arsenic derivatives

Journal of Thermal Analysis and Calorimetry
Authors: V. Ovchinnikov, T. Makeeva, L. Lapteva, V. Valiullina, L. Pilishkina, and A. Konovalov

Abstract  

The enthalpies of vaporization of different classes three-coordinated arsenic compounds have been determined according to their enthalpies of solution in hexane and molar refraction. The enthalpies of solvation of cyclic and acyclic As(III)-derivatives in hexane, carbon tetrachloride,p-xylene and pyridine are obtained and discussed.

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Journal of Thermal Analysis and Calorimetry
Authors: V. Ovchinnikov, E. Sagadeev, L. Lapteva, L. Khasieva, M. Alikberov, E. Sitnikova, I. Antipin, I. Stoikov, and A. Konovalov

Abstract  

The enthalpies of vaporization of different classes of phosphorylated alcohols and amines were determined from their enthalpies of solution in hexane and carbon tetrachloride. The enthalpies of specific (hydrogen-bond) interaction with the solvents (chloroform and pyridine) of derivatives containing X-H groups (X=O or N) in the α-position to the P=O group were determined. The results were explained in terms of the spatial structure of such compounds.

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Abstract  

Enthalpy of solution, ΔH sol o , enthalpy of sublimation, ΔH subl o , apparent partial molar volume and heat capacities,V 2 o andC p,2 o were determined for aqueous solutions of thirty alkylated derivatives of uracyl and adenine, eight derivatives of cytosine and guanine. Calculated accessible surface areas and molar volumes are presented, too. The values of enthalpy of solution, enthalpy of sublimation can be useful in the studies on the nature of interaction between these compounds and water molecules. Apparent partial molar volume and heat capacity give a new aspect on hydrophob properties of the examined nucleic acid base derivatives.

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Abstract  

Enthalpies of solution of dibenzo-18-crown-6 at infinite dilution have been measured in tetrachloromethane, benzene, chloroform, pyridine, acetone, dimethylformamide, dimethylsulfoxide, acetonitrile, benzyl alcohol and propylene carbonate at temperature of 298.15 K. Values for enthalpy of solvation and solute–solvent interaction in the solvents were determined. Correlation of enthalpies of solvation with the enthalpy of cavity formation and contribution for the different types of solute–solvent interaction was obtained. In benzene, tetrachloromethane, pyridine, DMF and DMSO polar conformer of DB18C6 dominates. Its effective dipole moment amounts to 3.7 D. Conformation dynamics of the solute reduces the effective polarity of such solvents as acetone, chloroform and propylene carbonate in which population of polar conformer of dibenzo-18-crown-6 decreases. Condensation of two benzene rings to 18-crown-6 results in increasing molecule polarity and exothermic contribution of dipole–dipole interaction in polar solvent media. The specific interaction with acetonitrile and chloroform becomes weaker from 18-crown-6 to dibenzo-18-crown-6.

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Solution enthalpies of hydroxylic compounds

Study of solvent effects through quantitative structure property relationships

Journal of Thermal Analysis and Calorimetry
Authors: Marina Reis, Luís Moreira, Nelson Nunes, Ruben Leitão, and Filomena Martins

extraction of specific interaction enthalpy from the enthalpy of solvation . J Phys Org Chem . 2005 ; 18 : 1 49 – 61 . 10.1002/poc.753 . 8. Kamlet , MJ , Taft , RW . Solvatochromic

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hydrophilic solutes: a calorimetric study . Thermochim Acta 2005 437 : 190 – 195 10.1016/j.tca.2005.05.012 . 19. Krestov , GA , Korolev , VP , Vandyshev , VN . Enthalpies of solvation of

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decrease in the enthalpy of solvation (or transfer) due to the addition of cosolvent to the solution can be attributed to the replacement of AN molecules within the solvation shell of electrolyte by stronger solvating molecules of cosolvent. The composition

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