Professor Ivo Leito, University of Tartu
Senior Research Fellow Ivari Kaljurand, University of Tartu
Prof. José Luis Abboud Mas (D.Sc.), Retired professor, Instituto de Química Física "Rocasolano", CSIC, Madrid, Spain
The thesis consist of two major sections. Firstly, pKa values of two sets of catalytically active compounds are measured. These experiments emphasize the need to know the properties of the solvent. Serious errors are revealed in case of compounds derived from phosphonic acids and their esters. These disparities are further investigated and explained in detail. Measurements with triarylphosphanes bring the need for 1,2-dichloroethane as a second solvent next to acetonitrile, due to the limits of the latter.
Secondly, the influence of water, the most common impurity in non-aqueous solvents, is systematically investigated at low concentrations in acetonitrile. It is shown that acids are more influenced by the rising water content compared to bases. The effect is studied by changing the strength of the acid-base properties of the compounds, the nature of the acidity/basicity center as well as the charge delocalization in ionized species.