Iron catalyzed demethylation of acetic acid*

The iron(IV)-oxo catalyzed cleavage of acetic acid is reported. Iron(II) complexes are used as catalyst precursors and H₂O₂ as oxidant in reactions in aqueous solution with an excess of chloride and, in some experiments, with ascorbic acid added as an OH^. radical scavenger. It is shown that the acetic acid is cleaved into CO₂ and a methyl radical. In the presence of O₂ and OH^. radicals, the initially generated methyl radicals produce methanol and formate. Halogenated alkanes are also formed and, in the absence of O₂ and OH^. radicals, methane is obtained as the major product. A mechanism for the formation of various environmentally important volatile C₁ compounds is deduced from the present results and published studies, and its relevance as an additional source for these compounds in the atmosphere is discussed.