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