A Common Active Intermediate in the Oxidation of Alkenes, Alcohols and Alkanes with H(2)O(2) and a Mn(II)/Pyridin‐2‐Carboxylato Catalyst

The mechanism and the reactive species involved in the oxidation of alkenes, and alcohols with H(2)O(2), catalysed by an in situ prepared mixture of a Mn(II) salt, pyridine‐2‐carboxylic acid and a ketone is elucidated using substrate competition experiments, kinetic isotope effect (KIE) measurements, and atom tracking with (18)O labelling. The data indicate that a single reactive species engages in the oxidation of both alkenes and alcohols. The primary KIE in the oxidation of benzyl alcohols is ca. 3.5 and shows the reactive species to be selective despite a zero order dependence on substrate concentration, and the high turnover frequencies (up to 30 s(−1)) observed. Selective (18)O labelling identifies the origin of the oxygen atoms transferred to the substrate during oxidation, and is consistent with a highly reactive, e. g., [Mn(V)(O)(OH)] or [Mn(V)(O)(2)], species rather than an alkylperoxy or hydroperoxy species.