Cross‐interaction constants as a measure of the transition state structure (part V). The transistion state structure for reactions of phenacyl benzenesulphonates with benzylamines in methanol

Abstract

Abstract The Kinetics of reactions of phenacyl benzenesulphonates with benzylamines were investigated in methanol at 45·0 °C and the cross‐interaction constants λ XY , λ YZ and β XZ were determined in order to elucidate the transition‐state structure. The unusually small magnitude of λ XY can only be accounted for by the resonance ‘shunt’ effect of the α‐CO group of the phenacyl system. Large |λ YZ | values indicate a small degree of bond breaking whereas relatively large |β XZ | values compared with those for the dissociative S N 2 reaction indicate a relatively tight transition state for the reactions. Further, the similar magnitudes of β XZ values compared with those of the corresponding aniline nucleophile series suggest a similar transition‐state structure for the two armatic amine nucleophile series.