The oxidation of HAC bonds in (e.g.) alkoxides, formate, and hydrocarbons and HAP bonds in phosphites and hypophosphites suggested that HAN bonds in ammonia, amines, etc. might provide interesting mechanistic studies. In aqueous solutions, MnO4 is reduced to Mn and/or Mn in acid or to MnO2y 4 in strong base (pH > 13). MnO4 does not oxidize NH 4 at an appreciable rate, so exploratory studies have been limited to solutions of ammonia with no added acid, using rapid scan spectrophotometry. Figure 1 shows the reduction of MnO4 in 15 M ammonia. Initially the spectra show MnO4 changing into Mn III with well de®ned isosbestic points. Late in the run, Mn begins to disproportionate into MnO2 and Mn . On long standing, the MnO2 precipitates leaving a clear solution. Most interesting is the very obvious acceleration of the rate of MnO4 decay through the ®rst half of the run. Absorbance data at 526ml and 420ml were used to calculate the concentrations of all Mn species, assuming only MnO4 and Mn III were present to the point of maximum rate and ®nal absorbance values were entirely due to MnO2 MnII 0:5co. Figure 2 shows calculated curves for the three absorbing species during one run. The initial rate is independent of NH3 from 3 M to 15 M. A rate law found for MnO4 decay is: dc=dt c k1 k2 co y c 1