Electronic and solvent effects on kinetics of SNAr substitution reactions of substituted anilines with 2,6-bis(trifluoromethanesulfonyl)-4-nitroanisole in MeOH-Me2SO mixtures of varying composition: one reaction with two mechanistic pathways.

摘要: The kinetics and mechanism of the aromatic nucleophilic substitution reactions 2,6-bis(trifluoromethanesulfonyl)-4-nitroanisole with para-X-substituted anilines (X = OH, OMe, Me, H, F, I, Cl) were studied in MeOH–Me2SO mixtures pure Me2SO at 25.0 °C. second-order rate coefficients depend on substitutent aniline give good Hammett Bronsted correlations; a polar SNAr reaction is proposed for different mixtures. measured demonstrated dramatic variations donor increasing dimethyl sulfoxide composition In this case, plots are biphasic concave upwards break point 4-methylaniline. These results indicate change from (SNAr) less basic nucleophiles (X = 4-Cl, 4-I, 4-F, H) to single electron transfer (SET) more (X = 4-OH, 4-OMe 4-Me). changes structure transitions states substituents solvent accordance studies. solvation model described well supported by solvatochromism exhibited mixture under investigation. provide an ideal framework understanding paramount importance specific molecular molecules determining chemical reactivity versus effects.