Solvent classification based on solvatochromic parameters: A comparison with the Snyder approach

Solvents play a major role in many chemical processes. Their effect is closely related to the nature and extent of solute/solvent interactions, developed locally in the immediate vicinity of the solutes, A new generation of empirical parameters helps to describe the solvent features in these microscopic environments, Their adequacy for the establishment of linear free energy relationships (LFER) has been widely proved. A classification scheme based on the microscopic properties of solvents is proposed, to provide a clearer insight into the solvent-space structure in terms of the similarity of solute/solvent interactions and to help chemists in the choice of a suitable solvent for each purpose. The Kamlet and Taft solvatochromic parameters alpha, beta and pi* have been selected as microscopic solvent descriptors, and solvent groups have been designed according to the results obtained from the application of several multivariate clustering techniques. The present scheme is compared with Snyder's triangle, an earlier solvent representation used extensively in chromatography. Analogies and differences which arise from the field of application and from the solvent descriptors used in each classification scheme are discussed.