Kinetics of aromatic nucleophilic substitution by toluene-p-thiolate in dimethylformamide. Effect of solvent on Hammett-type correlations

Abstract

The kinetics of the reaction of some 4-substituted 2-nitrochlorobenzenes with toluene-p-thiolate in dimethylformamide have been measured at temperatures from –39·7 to 71·9 °C. Correlation of rates by Hammett-type equations gives, using the best set of σ values, ρ=+6·65 at 10 °C. The dependence of the ρ value on the solvent is discussed. A comparison of these reactions with those of Ar₂CCHCl and of ArCCCl with the same nucleophile–solvent system shows that the substituent effects are markedly attenuated by the interposition of CC or CC bonds.