Maria Burger

Reduction of bromine(V) by tris(1,10-phenanthroline)-iron(II) in aqueous sulfuric acid

The kinetics and mechanism of the reduction of bromate by Fe(phen)32+ depend upon the concentration ratio of the reactants. At [Fe(phen)32+]≶[BrO3−] the rate-determining step is the dissociation of Fe(phen)32+; at [Fe(phen)32+]≪[BrO3−] the reaction is autocatalytic. A duality in the behaviour of Fe(phen)32+ is pointed out.AbstractКинетика и механизм восстановления бромата с помощью Fe(phen)32+ зависит от отношения концентраций реагентов. При условии [Fe(phen)32+]≷BrO3− ступенью, лимитирующей скорость реакции является диссоциация Fe(phen)32+; а при условии [Fe(phen)32+]≷BrO3− реакция становится автокаталитической. Обсуждается двойственность в поведении Fe(phen)32+.

Oscillations in the Belousov–Zhabotinsky reaction with sorbitol in the presence of bromine

The reaction of sorbitol with bromate in strongly acidic solution was found to induce temporal oscillations in the presence of large amounts of elementary bromine, both with cerium and manganese ions as catalysts. A systematic study of oscillations in this variant of the Belousov–Zhabotinsky reaction was carried out in a broad concentration range of the reagents. For the explanation of oscillations, a mechanism is proposed which is based on the well-known bromate chemistry combined with an organic radical control which takes into account the special reactions of sugars and sugar alcohols in the presence of bromine.

On the Preoscillatory Period of the Belousov-Zhabotinsky Reaction: A Search for Intermediates

In the Belousov-Zhabotinsky systems, where the catalytic oxidative bromination of malonic acid [MA] takes place with bromate, oscillations start only after a preoscillatory period. Intermediates formed during this part of the reaction initiate the transition from the non-oscillatory to the oscillatory state of the system.