INTRODUCTION
Glycols and glycol ethers are widely used as additives in food and cosmetics industries. Therefore, systems containing glycols and glycol ethers in mixtures with water, alkanes, and salts are actively studied [1–3]. These systems are the subjects of the current work because experimental and theoretical foundation for their application is lacking. There should be thermodynamic models that would be able to predict properties of pure components and phase equilibrium in systems containing glycols and glycol ethers with high accuracy.
For some of the members of the homology series, enthalpies of vaporization and melting are unknown or have not been measured with sufficient accuracy. In work [4] it has been noted that calculation of the parameters of eutectics and azeotrope mixtures used in technological processes of crystallization and rectification is complicated by the absence of accurate data on enthalpies of phase transitions of individual components.
Boiling temperature Tb and melting temperature Tm, pressure P, density ρ, enthalpy of vaporization ∆Hvap, and enthalpy of melting ∆Hm are determinative for computation of thermodynamic properties of pure substances and solutions. Prediction of the compound properties implies that the properties are determined basing on the compound structural formula. The theory connecting the structure of a molecule with its macroscopic parameters is not complete yet; therefore, it is necessary to summarize empirical data on the properties of various compounds. Method of thermodynamics similarity, which is a part of general similarity theory, forms theoretical basis for such a summary [5].
Enthalpy of vapor formation at normal temperature of boilingis called the enthalpy of vaporization. Solid–liquid and liquid–vapor phase transitions proceeding at normal temperature of melting are characterized by enthalpy of melting and enthalpy of vaporization. Methods of group contribution [6, 7] and quantum chemistry [8] are used for predictions.
