Mechanism of the Protonation of Ferrocenylacetic Acid by Perchloric Acid

Electron spectroscopy shows that the formation of ferrocenium cations upon the protonation of FcCH(2)COOH by perchloric acid in dioxane is a result of the redox isomerism of carbocation FcC(+)H(2). The latter forms during the fragmentation of acyl ion FcCH(2)C(+)O, the primary product of protonation. The extreme nature of the dependence of the rate of accumulation of ferrocenium cations on the concentration of FcCH(2)COOH as a result of it reacting with FcC(+)H(2) distinguishes this process from those of the protonation of other derivatives of ferrocene.