A phosphate catalyzed reaction of iodine with hydrazine in aqueous solutions

Pulse radiolysis was utilized to study the kinetics of the iodine-hydrazine reaction in aqueous solutions containing phosphate buffer in the pH range 5.5 to 7. The reaction rate was found to be proportional to and I^–]^–1, but did not show simple proportionality to H⁺]^–1 and was considerably higher than that found earlier when the pH of solutions was adjusted with HClO₄ or H₃BO₃. The results are in a formal agreement with the assumption that in phosphate buffered solutions a complex N₂H₄. HPO ₄ ^2– is formed, reacting with I₂ with a rate constant which is greater than that ascribed earlier to the reaction of N₂H₄ with I₂/Ref. 1/.