The action of p‐toluenesulphonyl chloride on pyridine‐n‐oxide (III)

The reaction mixture formed during the heating of pyridine‐N‐oxide with p‐toluenesulphonyl chloride contains, together with pyridine, 2,3′‐dipyridyl ether, 3‐pyridyl p‐toluenesulphonate and N‐(2Prime;‐pyridyl)‐pyridone‐2 two chloro compounds, viz. N‐(2′‐pyridyl)‐5‐chloro‐pyridone‐2, which is the chief product, and N‐(2′‐pyridyl)‐3‐chloro‐pyridone‐2. In this connection the formation of brominated derivatives of N‐(2′‐pyridyl)‐pyridone‐2 during the reaction of pyridine‐N‐oxide and 2‐bromopyridine, as described by Ramirez and von Ostwalden is discussed.