The thermal decomposition of copper(II) permanganate has been studied
between 335 and 370 K. Isothermal yield-time curves for the evolution
of product oxygen (1.27 mol O2 per mol Cu(MnO4)2) were sigmoid shaped
and data fitted the Avrami-Erofe'ev equation (n = 2): [-ln(1 - alpha)]
1/2 = kt, between 0.03 < alpha < 0.93 (where alpha is the fractional r
eaction). The activation energy for decomposition was 115 +/- 15 kJ mo
l-1. In the mechanistic discussion presented it is concluded that anio
n breakdown occurred at the interface between the crystalline reactant
and an ill-crystallized, probably several constituent, disorganized m
ixture of residual products. Permanganate anion breakdown is believed
to follow electron transfer to a Cu2+ ion (--> Cu+) that is subsequent
ly reoxidized. A principal motivation for the work was as a route for
the preparation of a non-stoichiometric, imperfect, microcrystalline m
ixture of transition metal oxides. The product of the present reaction
is being investigated to determine its value as a precursor for the p
reparation of active heterogeneous oxidation catalysts.