The reaction of halophenylhydrazines with oxygen in the presence of oxyhemoglobin and metal ions.

We have compared the rates of reaction of ortho and para substituted halophenylhydrazines with oxygen, and we have found that the reaction rates of these phenylhydrazines are accelerated by metal ions and oxyhemoglobin. Stimulation of the reaction rate by oxyhemoglobin was 20-times that by Fe3+ at the same concentration. In the presence of oxyhemoglobin, the initial decrease in the concentration of oxygen was followed by an increase. We propose that phenyldiazene produced from the oxidation of phenylhydrazine by oxyhemoglobin reduced oxygen to superoxide and caused the initial rapid decrease in oxygen concentration. The partial restoration of oxygen in the reaction mixture could be accounted for by the dismutation of superoxide to oxygen and hydrogen peroxide, and of hydrogen peroxide to oxygen and water.