STRUCTURE-REACTIVITY CORRELATION IN THE PYRIDINOLYSIS OF SUBSTITUTED PHENYL ACETATES

Article abstract of DOI:10.1016/S0040-4020(01)81723-3

The pyridinolysis of substituted phenyl acetates in acetonitrile was investigated with an electric conductivity method.The rates of these reactions were increased with electron-donating group in pyridine and electron-withdrawing group in phenyl acetate. ρ_X (X;substituents in phenyl ring) values increase gradually according to the electron-donating ability in pyridine substituents, but the /ρ_Y/ (Y;substituents in pyridine ring) values decrease with that of substituents.The β values increase with increasing electron-withdrawing ability of the substituents in the phenyl ring, it can be inferred that N---C bond formation increases progressively p-methyl to p-nitrophenyl acetates.This is in agreement with prediction of substituent effects for a simple S_N2 displacement reaction.The sensitivity parameters, β and ρ, are inter-related and are themselves sensitive to the reactivity of the system.All above results are interpreted in terms of a dissociative S_N2 mechanism involving a metastable tetrahedral intermediate.