Oxidation with the “O2−H2O2—vanadium complex—pyrazine-2-carboxylic acid” reagent11. Oxidation of styrene, phenylacetylene, and their derivatives with the formation of benzaldehyde and benzoic acid

The vanadium complex—pyrazine-2-carboxylic acid (PCA) system catalyzes oxidation of styrenes PhRC=CHR′ (R=H, Me; R′=H, Ph), or phenylacetylenes PhC=CR (R=H, Ph) with hydrogen peroxide in air to give aldehydes, ketones, and carboxylic acids. The reaction begins with H2O2 coordination to the vanadium ion followed by the formation of hydroxyl radicals. Catalytic action of PCA facilitates the reduction of the VV complex to the VIV complex and/or the stage of the formation of a peroxide derivative of vanadium.