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A Study of the Kinetic and Mechanism of Oxidation of Pyrazole Derivative by Permanganate Ion in Neutral Medium and the Effect of Metal Ion Catalysts

مؤلف البحث
Ismail Althagafi, Ahmed Fawzy
ملخص البحث

Oxidation of methylaminopyrazole formamidine (MAPF) by permanganate ion was studied spectrophotometrically in neutral medium in the presence of phosphate buffer solution. The stoichiometry of the reaction was found to be 3: 2 (MAPF: MnO4 - ). The oxidation reaction showed a first order kinetics with respect to [MnO4 - ] and a fractionalfirst order dependence with respect to [MAPF]. Addition of small amounts of some metal ions increased the oxidation rate and the order of catalytic efficiency was: Ag(I) > Cu(II) > Al(III). The suggested oxidation mechanism involves formation of a 1:1 intermediate complex between permanganate ion and MAPF. The formed complex decomposes in the rate-determining step to yield a free radical derived from MAPF and an intermediate Mn(VI). The free radical is attacked by Mn(VI) species to give rise to the final oxidation products which were identified by both spectroscopic and chemical tools as methylaminopyrazole, dimethylamine and carbon dioxide. The rate-law expression was deduced and the reaction constants involved in the different steps of the suggested mechanism were evaluated. The activation parameters of the rate constant of the slow step along with the thermodynamic quantities of the formation constant of the intermediate complex were evaluated and discussed.

تاريخ البحث
مستند البحث
مجلة البحث
American Journal of Heterocyclic Chemistry
المشارك في البحث
عدد البحث
2
سنة البحث
2016
صفحات البحث
1-7