Structure and Reaction Pathways of Methyl Pyruvate on Pd(111)

Abstract

The surface chemistry of methyl pyruvate is studied on a clean Pd(111) surface by using a combination of temperature-programmed desorption (TPD) and reflection−absorption infrared spectroscopy (RAIRS). It is found that methyl pyruvate adsorbs molecularly at low temperatures with an orientation that changes depending on coverage. At low coverages, it adsorbs with its molecular plane parallel to the surface, while as the coverage increases it bonds perpendicular to the surface in a trans conformation. The perpendicular form desorbs molecularly at ∼205 K, while a portion of the flat-lying form desorbs at between 270 and 300 K, and the reminder thermally decomposes. This appears to take place via an initial C−OCH3 bond scission to form adsorbed pyruvate species that decompose at higher temperature to form acetyl and acyl species along with ethylidyne.