Collect. Czech. Chem. Commun. 1981, 46, 1116-1123

Substitution at hydrazo group and stability of some hydrazo compounds

Vlasta Madajová and Imrich Zelenský

Department of Analytical Chemistry, Comenius University, 816 50 Bratislava


The effects of pH and of substitution at the hydrazo group on the rate of disproportionation were studied for some hydrazo compounds. Spectrophotometric investigation of the acid-base equilibria, polarographic measurements, and preparative electroreduction evidenced that the disproportionation is always acid catalyzed. The nonmonotonic dependence of the disproportionation rate on the pH of the solution is due to a change in the electron donor or electron acceptor effect of the substituent resulting from a shift in the acid-base equilibrium between the various forms of the hydrazo compound in question.