Ruthenium(III)‐mediated oxidation of D‐mannitol by cerium(IV) in aqueous sulfuric acid medium: A kinetic and mechanistic approach

Abstract

The oxidation of D-mannitol by cerium(IV) has been studied spectrophotometrically in aqueous sulfuric acid medium at 25 • C at constant ionic strength of 1.60 mol dm −3 . A microamount of ruthenium(III) (10 −6 mol dm −3 ) is sufficient to enhance the slow reaction between D-mannitol and cerium(IV). The oxidation products were identified by spot test, IR and GC-MS spectra. The stoichiometry is 1:4, i.e., [D-mannitol]: [Ce(IV)] = 1:4. The reaction is first order in both cerium(IV) and ruthenium(III) concentrations. The order with respect to D-mannitol concentration varies from first order to zero order as the D-mannitol concentration increases. Increase in the sulfuric acid concentration decreases the reaction rate. The added sulfate and bisulfate decreases the rate of reaction. The active species of oxidant and catalyst are Ce(SO 4 ) 2 and [Ru(H 2 O) 6 ] 3+ , respectively. A possible mechanism is proposed. The activation parameters are determined with respect to a slow step and reaction constants involved have been determined.

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

“…According to Eqs. (10) and (11), plots of 1/k obs versus 1/[Py-F] at constant [H + ], and 1/k obs versus [H + ] at constant [Py-F] should be linear with positive intercepts and are found to be so as shown in Figures 5 and 6, respectively. From the slopes and intercepts of these plots, the values of k 1 , K OH , and K could be evaluated and were found to be 31.25 x 10 -3 s -1 , 0.17 mol dm -3 , and 202.17 dm 3 mol -1 , respectively at 20 °C.…”

“…Cerium(IV) is a powerful one electron oxidizing agent in acid media [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Oxidation by cerium(IV) in sulfuric acid solutions have conclusively been established [5][6][7][8][9][10][11][12][13]. Nevertheless, little reports on cerium(IV) oxidation in perchloric acid solutions [14][15][16][17][18][19], probably due to presence of dimers and polymers of cerium(IV) in such solutions [19].…”

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

“…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].…”

“…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]. 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].…”