The reactivity of some primary amines in SN2Ar reactions with 2- and 4-chloro-1-methylpyridinium ions

Abstract

Rate constants for the S_N2Ar reactions of 2- and 4-chloro-1-methylpyridinium ions with butylamine, glycine, glycylglycine, and ethylenediamine monohydrochloride, in water at 1.0 mol dm^–3 constant ionic strength and 25 °C have been determined. For all amines studied k_obs is found to be related to free-amine concentration, [A], as k_obs=k_o+k₁[A]. The 2-isomer was always more reactive than the 4-isomer. The Brønsted β coefficients are 0.66 for the 2-isomer and 0.49 for the 4-isomer. These reactions seem to be charge-controlled. From the derived Edwards-equation results one could infer that the 2-isomer might tend to interact by way of its charge more than the 4-isomer.