Reaction of N-heteroaromatic bases with nitrous acid. Part 8. Kinetics of the diazotisation of 1-methyl- and 1-methoxy-4-aminopyridinium perchlorate in aqueous perchloric acid

Abstract

The diazotisation of 1-methyl-4-aminopyridinium perchlorate in 0.25–5.00M-perchloric acid is of first order in both the amine and nitrous acid. The rate coefficients increase with an increase in the concentration of perchloric acid and sodium perchlorate. In perchloric acid solutions whose ionic strength is maintained constant by the addition of sodium perchlorate the rate coefficients of the diazotisation of 1-methyl- and 1-methoxy-4-aminopyridinium perchlorate show a rectilinear dependence on the h_o parameter of the medium. It is suggested that the reaction involves an initial interaction between the nitrosating agent and the heteroaromatic nucleus of the 1-methyl- or the 1-methoxy-4-aminopyridinium ion. pK_a Values are recorded.