Empirical approach to description of solvent effect on processes in solutions: A review

Abstract

The review summarizes and evaluates the empirical models used for description of effects of solvents and solvent mixtures on processes in solutions. Analyzed are the principles of application of the empirical relations and their theoretical basis. A survey is given about empirical parameters of individual solvents with respect to the model process and also about the parameters derived by mathematical-statistical treatment. Also analyzed is the relation between the individual parameter scales, and their physical meaning is evaluated. Furthermore the review gives a survey of relations with empirical parameters used for description of effects of individual solvents on processes in solutions and presents results of tests of selected equations with a set of 368 experimental data series. The Kamlet & Taft equation in the basic version (only with the π*, α, and β parameters), has been evaluated as the best one, the best parameter according to the STEPWISE procedure being the π* parameter by Kamlet & Taft and the BASITY parameter by Swain et al. The best fit has been found for the processes involving electronic excitation of molecules in absorption and fluorescence spectroscopy. The section concerning mixed solvents presents a survey of empirical models used for description of effect of changes in composition of solvent mixtures on processes in solutions. The testing with 29 data series has shown the practically advantageous properties of the relations based on application of the additional Gibbs function expressed by empirical linear expansion (Margules).