Oxidation of formic and oxalic acids by imidazolium fluorochromate in non-aqueous media - A kinetic and mechanistic study

Kinetics and mechanism of oxidation of formic and oxalic acids by imidazolium fluorochromate (IFC) have been studied in dimethyl sulphoxide (DMSO). The main product of oxidation is carbon dioxide. The reaction is first order with respect to IFC and organic acids. The reaction is acid catalyzed and the acid dependence has the form : k(obs) = a + b [H+]. The oxidation of alpha-deuterio formic acid exhibits a substantial primary kinetic isotope effect (k(H)/k(D) = 5.63 at 303 K). The reaction has been studied in nineteen different organic solvents and solvent effect analyzed using Kamlet-Taft and Swain's multi parametric equations. The temperature dependence of the kinetic isotope effect indicates the presence of a symmetrical cyclic transition state in the rate determining step.