Klachko O. Thermodynamic properties of 6-methyl-2-oxo-4-aryl-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid esters and their solutions in organic solvents

An important scientific and practical problem for the field of knowledge 10 Natural sciences was solved in this dissertation research, namely the thermodynamic properties of seven esters of 6-methyl-2-oxo-4-aryl-1,2,3,4-tetrahydropyrimidine-5 carboxylic acid and their solutions in organic solvents were determined. Derivatives of the tetrahydropyrimidine series are widely used in the pharmaceutical industry, due to the wide range of their properties. However, despite the importance of this class of compounds, their thermodynamic properties is insufficiently studied. There are no enthalpy characteristics in the literature that would provide the existing schemes for calculating the enthalpies of formation, evaporation, sublimation and dissolution. That is why the study of the thermodynamic parameters of dihydropyrimidine derivatives is an important task of thermodynamics. The relevance of the research is determined both from a theoretical point of view - an explanation of the features and specifics of the structural structure, nature of intermolecular and intramolecular bonds, and from a practical point of view - the development of new techniques that would simplify and improve the synthesis and purification of tetrahydropyrimidines characteristics. The results of experimental studies are: − for the first time the following thermodynamic parameters: enthalpy of combustion, enthalpy of formation in the condensed state, enthalpy of evaporation sublimation, enthalpy of dissolution, temperature dependences of solubility were experimentally obtained for seven representatives of the class of esters of 6 methyl-2-oxo-4-aryl-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid; − the influence of the properties of the investigated compounds on the thermodynamic parameters of their solutions in organic solvents is analyzed; − the possibility of using additive schemes to calculate the enthalpy of formation of this class of compounds is analyzed. The obtained values of thermodynamic quantities make it possible to optimize the processes of obtaining the studied series of compounds (standard enthalpy of formation and combustion, enthalpy of evaporation), as well as for the processes of their separation and purification (solubility in organic solvents).