Oxidations by the reagent “O2–H2O2–vanadium derivative–pyrazine-2-carboxylic acid’. Part 12. Main features, kinetics and mechanism of alkane hydroperoxidation†

Vanadate ion-catalyzed oxidation of methane with hydrogen peroxide in an aqueous solution

“…The vanadate ion-PCA combination in a 1 : 4 ratio was used. Earlier, it was shown [26] that the highest rate of alkane oxidation in acetonitrile was achieved at this catalyst-to-cocatalyst ratio. From the data presented in Table 1, it follows that an increase in the concentration of water from 0.7 mol/l (1.3 vol %) to 1.6 mol/l (2.8 vol %) results in the complete suppression of the oxidation of methane.…”

“…Obtaining products of the partial oxidation of the most inert alkane methane is an especially challenging problem. It is known that vanadium derivatives catalyze the oxidation and oxidative functionalization of alkanes, including methane [10][11][12][13][14][15][16].Earlier, we found that a vanadate anion in an acetonitrile solution catalyzes the effective oxidation of saturated hydrocarbons with air oxygen in the presence of hydrogen peroxide at low temperatures ( 20-70° C) [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The presence of pyrazine-2-carboxylic acid (PCA) as a cocatalyst in concentrations that sometimes exceed the concentration of a vanadium complex is a necessary condition for the reaction.…”

“…It was assumed [26] that the PCA anion coordinated to vanadium facilitates the processes of the proton transfer between ligands in the vanadium coordination sphere and, thus, accelerates the reaction of the generation of hydroperoxyl and hydroxyl radicals. Bell et al [31] performed a density functional theory (DFT) study of our reagent.…”

“…Earlier, we found that a vanadate anion in an acetonitrile solution catalyzes the effective oxidation of saturated hydrocarbons with air oxygen in the presence of hydrogen peroxide at low temperatures ( 20-70° C) [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. The presence of pyrazine-2-carboxylic acid (PCA) as a cocatalyst in concentrations that sometimes exceed the concentration of a vanadium complex is a necessary condition for the reaction.…”

The kinetics and mechanism of oxidation of isopropanol with the hydrogen peroxide-vanadate ion-pyrazine-2-carboxylic acid system

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INTRODUCTIONWe found earlier that the V vanadate anion effectively catalyzed the oxidation of saturated and aromatic hydrocarbons with hydrogen peroxide in acetonitrile in air at temperatures of from 20 to 70°C [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The necessary condition for the reaction to occur was the presence of pyrazine-2-carboxylic acid (PCA) as a cocatalyst in concentrations several times higher than the concentration of the vanadium complex.

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