Characterization of Solvent Mixtures: Preferential Solvation of Chemical Probes in Binary Solvent Mixtures of polar Hydrogen Bond Acceptor Solvent with polychlorinated co-solvents

P.M. MANCINI, A. TERENZANI, C. ADAM, A. PÉREZ AND L.R. VOTTERO

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY

J. Wiley & Sons Ltd

Lugar: Illinois, USA; Año: 1999 vol. 12 p. 713 - 724

0894-3230

The use of chemical probes for hte cahraterization of chemicalpreoperties is explores for aprotic binary solvent miextures. The solvatochromic indicator N,N-diethyl-4-nitroaniline, 4-nitroanisole, 4-mitroaniline and 4-nitrophenol were used to characterize binary mixtures of a polar aprotic hydrogen-bond acceptor solvent (ethyl acetate, acetonitrile,and dimethyl sulfoxide) with a polychlorinated hydrogen-bond donor solvent (chloroform or dichloromethane). The solvent parameters pi, alpha and beta of the binary mixtures wrew calculated form the solvatochromic shifts of the indicators. In each case the degfree of convergence for a solvent propety values obtained from different probes was analyzed- Data obtainde by using the non-polar sovatochromic indicator bta-carotene are addtionally presented. The behavior of the solvent systems was analyzed according to their deviation from ideality due to preferentialsolvatio of the solutes and the complicated intermolecular interactions of a solvent mixtures and whether such a propety can be defined by means of chemical probes is dicussed. Theoretical equations (preferential solvatio models) were used to compute the solvatochromic data. The results were  analyzed and related to the solvent effects on some aromatic nucleophilic substitution reactions, comparing the application of single- and miltiparmetric treatments of solvent effects.