Kinetics and Mechanistic Study of Permanganate Oxidation of Fluorenone Hydrazone in Alkaline Medium

Ahmed Fawzy,Moataz H Morad,Ismail I Althagafi,Khalid S Khairou,Saleh A Ahmed

doi:10.1155/2016/4526578

Ahmed Fawzy, Moataz H Morad + Show 3 more

Open Access

https://doi.org/10.1155/2016/4526578

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Abstract

The oxidation kinetics of fluorenone hydrazone (FH) using potassium permanganate in alkaline medium were measured at a constant ionic strength of 0.1 mol dm−3 and at 25°C using UV/VIS spectrophotometer. A first-order kinetics has been monitored in the reaction of FH with respect to [permanganate]. Less-than-unit order dependence of the reaction on [FH] and [OH−] was revealed. No pronounced effect on the reaction rate by increasing ionic strength was recorded. Intervention of free radicals was observed in the reaction. The reaction mechanism describing the kinetic results was illustrated which involves formation of 1 : 1 intermediate complex between fluorenone hydrazones and the active species of permanganate. 9H-Fluorenone as the corresponding ketone was found to be the final oxidation product of fluorenone hydrazone as confirmed by GC/MS analysis and FT-IR spectroscopy. The expression rate law for the oxidation reaction was deduced. The reaction constants and mechanism have been evaluated. The activation parameters associated with the rate-limiting step of the reaction, along with the thermodynamic quantities of the equilibrium constants, have been calculated and discussed.

Highlights

Fluorene and its derivatives (FLs) are a unique class of polycyclic aromatic hydrocarbons (PAHs) which exist in the fossil fuels and petrogenic sources burning of gasoline [1, 2]
Fluorenone hydrazones are used as precursors for the synthesis of photochromic di- and tetrahydroindolizines [14,15,16] and more recently as efficient corrosion inhibitors [17]
The kinetic measurements were followed under pseudo-first-order conditions where fluorenone hydrazone substrate existed in a large excess over that of permanganate

Summary

Introduction

Fluorene and its derivatives (FLs) are a unique class of polycyclic aromatic hydrocarbons (PAHs) which exist in the fossil fuels and petrogenic sources burning of gasoline [1, 2]. Hydrazone derivatives were found to be biologically important class of compounds [12]. To the best of our knowledge, there are no reports on the kinetics and mechanism of oxidation of fluorenone hydrazone. This motivates us to investigate the kinetics and mechanism of oxidation of fluorenone hydrazone with permanganate ion in alkaline medium. The objectives of the present study aimed to shed more light and establish the most favorable conditions affecting oxidation of such noteworthy compound and to elucidate a plausible oxidation reaction mechanism

Experimental

Results and Discussion

H N—N—OMnO3

Conclusions