Nitrogenhyphen;Isotope Effects in the Reduction of Nitrate, Nitrite, and Hydroxylamine to Ammonia. I. In Sodium Hydroxide Solution with Fe (II)

摘要

Studies were made of the nitrogenhyphen;isotope effects occurring during the alkaline reduction of NO3minus;, NO2minus;, and NH2OH with Fe(II). The pertinent reduction reactions were shown to be irreversible and the yields of NH3quantitative. The reduction of NO3minus;to NH3produced ak14/k15value of 1.075plusmn;0.004 at 25deg;C. Ak14/k15ratio of 1.034plusmn;0.002 at 25deg;C was obtained for the reduction of NO2minus;, or NH2OH to NH3. The rate constant,kNO3minus;, was shown to be slow compared tokNO2minus;andkNH2OHwhich had values of 4.09times;10minus;2and 9.53times;10minus;3secminus;1, respectively.The experimental data agreed well with results computed for a twohyphen;atom model in which the significant step in the reduction of each species was the breaking of an Nsngbnd;O bond. Reactions consistent with the experimental data were proposed to account for the reduction mechanism.