Catalytic, Oxidative Condensation of CH₄ to CH₃COOH in One Step via CH Activation

Acetic acid is an important petrochemical that is currently produced from methane (or coal) in a three-step process based on carbonylation of methanol. We report a direct, selective, oxidative condensation of two methane molecules to acetic acid at$180\textdegree C$in liquid sulfuric acid. Carbon-13 isotopic labeling studies show that both carbons of acetic acid originate from methane. The reaction is catalyzed by palladium, and the results are consistent with the reaction occurring by tandem catalysis, involving methane C-H activation to generate$Pd-CH_3$species, followed by efficient oxidative carbonylation with methanol, generated in situ from methane, to produce acetic acid.