KINETICS OF ADDITION OF N-BUTYLAMINE TO 4'-SUBSTITUTED N-METHYL-2-STRYLPYRIDINIUM IODIDES

The kinetics of addition of n-butylamine to 4'-substituted N-methyl-2- styrylpyridinium iodides in acetonitrile have been followed spectropho tometrically. The reaction is first order with respect to the substrat e and the order in n-butylamine is non-integral. A mechanism involving the formation of the zwitterionic addition complex in the first equil ibrium step with subsequent proton transfer in a slow step is proposed . Structure-reactivity study with various 4'-substituents shows that t he rate of proton transfer is accelerated by electron-releasing substi tuents and retarded by electron-withdrawing substituents.