Characterization of Solvent Mixtures: Preferential Solvation of Chemical Probes in binary Solvent Systems of Apolar Aprotic Hydrogen Bond Acceptor Solvent with Acetonitrile or Nitromethane. Part 8.

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. 207 - 217

0894-3230

The use of chemical probes for the characterization of chemical properties was explored for completely non-aqueous aprotic binary solvent mixtures. The Dimroth-Reichardt betaine dye, 4-nitrophenol, 4-nitroanisole, 4-nitroaniline and N,N-diethyl-4-nitroaniline were used to study preferential solvation in binary mixtures of a polar aprotic hydrogen bond-acceptor solvetn (DMSO,DMF, acetone, butanone and ethyl acetate) with acetonitrile or nitromethane at 25ºC over the whole range of solvent composition. The indicators wrew employed to determine ET(30), pi, alpha, beta solvatochromic parameters of the mixtues. Each solvent system was analysed according to its deviation form ideal behaviour due to the preferential solvation of the indicators and also form the property of a solvent mixture and whether such a property can be defined by means of chemical probes is dicussed. These results wre related to the solvent effects on same aromatic nucleophilic substitution reactions. The kinetics of the reactions between 1-fluor-2,4-dinitrobenzene and primary or secondary amines were studied in ethyl acetate-acetonitrile and N,N-dimethylformamide-acetonitrile mixtures, respectively, taken as respersentatives of two clearly different solvation models.