Reactions of N-heteroaromatic bases with nitrous acid. Part II. The kinetics of the diazotisation of 4-aminopyridine

Abstract

The kinetics of the diazotisation of 4-aminopyridine have been studied in 0·0025–5·0M-perchloric acid. The reaction proceeds by one mechanism only, whose kinetic form is of first order with respect both to the amine and to nitrous acid. The rate of the reaction shows an exponential catalytic dependence on the concentration of added sodium perchlorate and a similar, but greater, catalytic dependence on perchloric acid. In solutions whose ionic strength is maintained constant by the addition of sodium perchlorate, the rate shows a linear dependence on the h₀ function. These results are interpreted in terms of the reaction between the protonated amine and nitrous acidium ion. They are similar to the results observed in the nitrosation of the more basic aromatic amines in perchloric acid above ca. 1 M.