Authors:V. Ovchinnikov, T. Makeeva, L. Lapteva, V. Valiullina, L. Pilishkina, and A. Konovalov
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.
Authors:V. Ovchinnikov, E. Sagadeev, L. Lapteva, L. Khasieva, M. Alikberov, E. Sitnikova, I. Antipin, I. Stoikov, and A. Konovalov
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.
Enthalpy of solution, ΔHsolo
, enthalpy of sublimation, ΔHsublo
, apparent partial molar volume and heat capacities,V2o
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
Authors:Vladimir Barannikov, Sabir Guseynov, and Anatoliy Vyugin
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.
decrease in the enthalpyofsolvation (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