Kinetics and Mechanistic Study of Oxidation of Pyridine Derivative by Cerium(IV) in Aqueous Perchloric Acid

Abstract

The kinetics of oxidation of N, N-dimethyl-N'-(pyridin-2-yl) formamidine (Py-F) by cerium(IV) was studied spectrophotometrically in aqueous perchloric acid solutions at a constant ionic strength of 1.0 mol dm-3 and at 20°C. The reaction showed first order dependence with respect to [Ce(IV)] and less than unit order with respect to [Py-F]. The reaction exhibited negative fractional-first order kinetics with respect to [H + ]. The rate of reaction was not significantly affected by variation of either ionic strength or dielectric constant of the reaction medium. Addition of cerium(III) product did not affect the reaction rate. A suitable mechanistic scheme for the oxidation reaction has been proposed. The final oxidation products were identified as 2-aminopyridine, dimethylamine and carbon dioxide. The activation parameters have been evaluated and discussed. The rate law associated with the reaction mechanism was derived.

Oxidation of Formamidines by Cerium(IV) in Aqueous Perchlorate Solutions: A Kinetics and Mechanistic Approach

“…The progress of the reaction was followed by monitoring the decrease in absorbance of cerium(IV) as a function of timeat λ = 316 nm, its absorption maximum, whereas the other constituents of the reaction mixture do not absorb significantly at this wavelength. The applicability of Beer's law for cerium(IV) at 315 nm has been verified giving ɛ = 4371 ± 28 dm 3 mol −1 cm −1 in agreement with the earlier reports [11,12]. The absorbance measurements were made in a thermostatted quartz cell of a pathlength 1.0 cm on a Shimadzu UV-VIS-NIR-3600 double-beam spectrophotometer.…”

“…Cerium(IV) is a powerful one electron oxidizing agent in acid media [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Oxidation by cerium(IV) in sulfuric acid solutions have conclusively been established [1][2][3][4][5][6][7][8][9].…”

“…Oxidation by cerium(IV) in sulfuric acid solutions have conclusively been established [1][2][3][4][5][6][7][8][9]. Nevertheless, little reports on cerium(IV) oxidation in perchloric acid solutions [10][11][12][13][14][15][16][17], probably due to presence of dimers and polymers of cerium(IV) in such solutions [17]. However, the reactions of cerium(IV) in perchloric acid medium proceed much faster than those in sulfuric acid medium.…”

Silver-Catalyzed Oxidation of Atropine Drug by Cerium(IV) in Aqueous Perchlorate Solutions: A Kinetics and Mechanistic Approach

“…Cerium(IV) is a significant single electron oxidant in acid media [4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The oxidizing potentialities of cerium(IV) in sulfuric acid medium were conclusively established [10,11].…”

Kinetics and Mechanistic Approach to the Oxidation of Inositol by Cerium(IV) in Aqueous Perchlorate Medium

“…Cerium(IV) is a significant single electron oxidant in acid media [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. In perchlorate medium, this oxidant has rarely been employed [21,22], probably due to presence of dimers and polymers of cerium (IV) in such medium [22].…”