Collect. Czech. Chem. Commun. 1987, 52, 287-298

Effect of medium on electronic spectra of 4-dimethylamino-ω-nitrostyrenes. Effective Kirkwood-Onsager functions of medium

Vojtěch Bekárek and Vojtěch Bekárek, Jr.

Faculty of Natural Sciences, Palacký University, 771 46 Olomouc


Wavenumbers of the longest-wave maxima of 1-nitro-2-(4'-dimethylaminophenyl)ethene and 2-nitro-1-(4'-dimethylaminophenyl)propene have been measured in 60 aprotic solvents. The values obtained along with the published data on the effect of medium on electronic spectra of eight other indicators (also measured in gas phase) have been used to suggest effective Kirkwood-Onsager functions for characterization of the overall polarizability of medium, inclusive of the gas phase, in the sense of the method of the product term. Applicability of these functions has been tested for evaluation of the effect of medium on electronic and infrared spectra, reaction rates and equilibria. The effect of medium on the rate of the Menshutkin reactions is interpreted as a consequence of the influence on the fast process (1013 s-1) in the complex formed from the reactants.