Über ein- und zweiphasige Reduktion von γ-MnO2 durch Zimtalkohol

The reduction of γ-MnO₂ with cinnamic alcohol in xylene at 90° leads (1) to γ-MnOOH in a double phase reaction with germination if the α-MnO₂ is extremely disperse, and (2) to α-MnOOH in a strictly topotactical (single phase) reaction without germination if the γ-MnO₂ is relatively well crystallised. The hexagonality of the densest packed oxygens is not a linear function of the reduction rate but shows a discontinuity when about half of the Mn⁴⁺ are reduced, which is consistent with results of GABANO . The αMnOOH obtained by this reaction shows still the selective and asymmetric X- ray and electron reflection broadening of the reactant. Hence, the authors consider the product to possess an intergrowth structure of a Groutite matrix with statistically and layerwise distributed Manganite microdomains, according to a model proposed by DE WOLFF for α-MnO₂. The domains are supposed to have the size of one cell only in the b direction, and of a few cells in the a direction, and to be present in relatively small concentration.