Lukinova O. Peculiarities of physical and chemical properties of highly concentrated solutions of R4NX (R=Bu, Et, X=BF4, Br) in acetonitrile

The object of the study is a dependence of transport and thermodynamic properties of solutions of 1-1 electrolytes in non-aqueous solvents on the nature of the components, solution's composition and temperature. The aim of the study is to establish the regular patterns in the influence of temperature, concentration, nature and size of the ions, as well as the microscopic structure of the ionic subsystem on the physico-chemical properties of solutions of tetraalkylammonium salts in acetonitrile; to develop models of concentration dependence of electrical conductivity (EC) in solutions of 1-1 electrolytes. Research methods and apparatus are conductometry, viscometry, NMR spectroscopy, quantum- chemical calculations, AC bridge, conductometric cells, Ubelode viscometer, NMR spectrometer , thermostats, and computers. The theoretical and practical results obtained in the present work have revealed specific features of the microscopic structure of the ionic subsystem in highly-concentrated solutions of 1-1 electrolytes in non-aqueous solvents. The significant effect of ion association on the physico-chemical properties in the systems under study has been also found. The joint use of the quasicrystal model and the ion association model has been shown as a novel approach for prediction of the concentration dependence of EC in concentrated region. A relationship between the effective size of the ions in the electrolyte solution and the concentration at which a maximum specific EC of the solution is observed has been found. The evidence of formation of the contact ion pairs of penetrating type between the TAA cations and anions under study has been revealed. The results obtained in the present work were implemented in the educational process of chemistry faculty. Research laboratories that develop chemical current sources and supercapacitors hold an interest in the current research as well.