Kinetics of addition of <i>n</i>-butylamine to 4'-substituted N-methyl2-styrylpyridinium iodides

Abstract

The kinetics of addition of <i>n</i>-butylamine to 4'-substituted N-methyl-2-styrylpyridinium iodides in acetonitrile have been followed spectrophotometrlcally. The reaction is first order with respect to the substrate and the order in <i>n</i>-butylamine is non-integral. A mechanism involving the formation of the zwitterionic addition complex in the first equilibrium step with subsequent proton transfer in a slow step is proposed. Structure-reactivity study with various 4'-substituents shows that the rate of proton transfer is accelerated by electron-releasing substituents and retarded by electron-withdrawing substituents.