The kinetics of the oxidation of 1,10-phenanthroline (1,10-phen) by permang
anate were investigated in alkaline medium. A first-order, fractional-order
and zero-order dependence of the rate each in [MnO4-], [1,10-phen] and [OH
-], respectively, was observed. The data suggest that the oxidation proceed
s via the formation of a complex between 1,10-phen and MnO4- which decompos
es in a slow step to yield the free radical of 1,10-phen, followed by a fas
t step to give 2,2'-bipyridyl 3,3'-dicarboxaldehyde. The reaction constants
involved in the mechanism were evaluated. There was good agreement between
the observed and calculated rate constants under varying conditions of the
experiments. The activation parameters were calculated with respect to the
slow step of the mechanism. Copyright (C) 1999 John Wiley & Sons, Ltd.