Investigations on pyridine and quinoline derivatives: (42nd. Communication) The formation of (4‐pyridyl)‐pyridinium compounds from 4‐chloropyridine and 4‐bromopyridine

Abstract

Abstract 4‐Chloropyridine undergoes slow conversion into N‐(4‐pyridyl)‐4′‐chloropyridinium chloride from which the already known N‐(4‐pyridyl)‐4′‐pyridone is obtained on hydrolysis. 4‐Bromopyridine changes rapidly into N‐(4‐pyridyl)‐4′‐bromopyridinium bromide, which also affords N‐(4‐pyridyl)‐4′‐pyridone on hydrolysis Improved recipes are given for the preparation of 4‐chloro‐ and 4‐bromopyridines in yields of 75% and 45%, respectively