Reactions of N-heteroaromatic bases with nitrous acid. Part I. Diazotisation and nitrosation of α- and γ-amino-derivatives in dilute acid solutions

Abstract

The diazotisation of 2- and 4-aminopyridine in dilute mineral acid leads to the formation of diazonium ions. Pyridine-4-diazonium ion so obtained has been characterised as 4–2′-hydroxy-1′-naphthylazopyridine. These diazonium ions hydrolyse rapidly to the corresponding hydroxy-compounds in dilute acid solution. In alkaline solution, diazoate ions are formed and are much more stable.α- and γ-Methylamino-N-heteroaromatic bases nitrosate in moderately strong acid solution to secondary N-heteroaromatic nitrosamines which, unlike their aromatic analogues, hydrolyse in very weakly acid solutions.