The cobalt-catalyzed conversion of methyl formate into acetic acid

Abstract

Methyl formate can be selectively converted into acetic acid in quantitative yield by use of cobalt catalysts. Essential requirements include the presence of a tertiary amide as solvent, of an ionic iodide as promoter, a sufficiently high CO pressure (above 100 bar), and a reaction temperature between 160° and 180°C. Other alkyl formates are not transformed into acids. The reaction probably invovles, as the key step, the reduction of the cobalt(II) catalyst to a cobaltate species, which is then transformed into alkyl and acylcobalt species. The latter reacts with lithium formate, formed in situ, to afford a mixed anhydride, decarbonylation of which yields acetic acid with regeneration of CO.