Spectroscopic study of NEMCA promoted alkene isomerizations at PEM fuel cell Pd–Nafion cathodes

We recently reported the electrochemical promotion of the heterogeneously catalyzed isomerization of 1-butene to cis- and trans-butene with ρ values of 38 and 46, respectively, at the remarkably low temperature of 70°C using Nafion as the electrolyte in a fuel cell configuration. This was the first reported case of a NEMCA promoted unimolecular and non-redox reaction concomitant with the reduction of butene to butane. We now present isotopic mass spectral and FTIR data confirming the mechanism involves abstraction of a proton from the catalytic surface for Markovnikov addition to the C-1 carbon concomitant with removal of a proton from C-3 to yield the isomer. This striking example of an acid catalyzed reaction at a metal surface is facilitated by the use of the super acidic Nafion electrolyte.