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The catalytic partial oxidation of methane is achieved at low temperatures (90% at ∼35% methane conversion at approximately 6 turnovers. Under our catalytic methane oxidation reaction conditions, MeTFA is stable against overoxidation, which explains the likely high selectivity at conversions >15%. Using combined experimental studies and DFT calculations, a mechanism involving soluble and molecular Mn species in the catalytic cycle is proposed. The proposed reaction pathway involves initial activation of Mnᴵᴵ by dioxygen, cleavage of a methane C–H bond by a Mnᴵᴵᴵ hydroxo intermediate, rebound of the methyl radical to generate MeTFA, and finally regeneration of the starting MnII complex. Also, this process is shown to be applicable to the oxidation of ethane, favoring the mono-oxidized product ethyl trifluoroacetate (EtTFA) and reaching ∼46% conversion.

We report carbon-hydrogen acetoxylation of nondirected arenes benzene and toluene, as well as related functionalization with pivalate and 2-ethylhexanoate ester groups, using simple copper(II) [Cu(II)] salts with over 80% yield. By changing the ratio of benzene and Cu(II) salts, 2.4% conversion of benzene can be reached. Combined experimental and computational studies results indicate that the arene carbon-hydrogen functionalization likely occurs by a nonradical Cu(II)-mediated organometallic pathway. The Cu(II) salts used in the reaction can be isolated, recycled, and reused with little change in reactivity. In addition, the Cu(II) salts can be regenerated in situ using oxygen and, after the removal of the generated water, the arene carbon-hydrogen acetoxylation and related esterification reactions can be continued, which leads to a process that enables recycling of Cu(II).