Nucleophilic substitution reactions of allyl arenesulphonates with anilines and N,N-dimethylanilines

Abstract

Kinetic studies of the reactions of allyl arenesulphonates, I, with anilines and N,N-dimethylanilines in acetonitrile at 45.0 °C are reported. The sign and magnitude of the cross-interaction constants ρxz(andβxz) between substituents in the nucleophile (X) and leaving group (Z) indicate that the transition state (TS) for I is relatively tight and is similar to that for the corresponding reactions of ethyl systems, rather than for benzyl systems. Variations of the simple Hammett (and Bronsted) coefficients ρx(βx) and ρx(βx) with substituents Z and X, respectively, are consistent with the trend expected from a positive ρxzi.e., that predicted by the potential energy surface diagram. The kinetic isotope effects involving N-deuteriated anilines support the mechanism proposed based onρxz(βxz) for the reactions of I, i.e., an associative SN2 process with an earlier TS for a stronger nucleophile and/or a better leaving group.