Syntheses of 1-Alkylpyridinium-2-acylimides and Behavior of Them as a Zwitter Ionic Compound

Abstract

The title compounds [ 3 ] were synthesized by the alkali treatment of 1-alkyl-2-(acylamino) pyridinium halides [2], prepared from 2- (acylamino)pyridines [ 1 ] and alkyl halides. The characteristic IR spectra of carbonyl group in [ 3 ] shifted to lower frequencies than those of [1] and [2]. The chemical shifts of methyl or methylene protones, attached to nitrogen in pyridine ring in [3] appeared at a lower field than that in 1-alkyl-2-iminopyridine [ 4 ].The solubilities of [3] in water were higher than those of the corresponding [1]. The pro-perties and behavior of the aqueous solutions of [ 3] were similar to those of the amine imides. And, some of [3], with the suitable alkyl and/or acyl groups, showed an excellent ability to lower a surface tension of the solution. Therefore, the significant contribution of zwitter ionic structure of [3], especially in a polar solvent, can be presumed from these results.