Reactions of methylcyclopentane over supported-metal catalysts

Abstract

The exchange reaction of methylcyclopentane with deuterium has been carried out over supported palladium, platinum and rhodium catalysts and the products analysed by mass spectrometry and deuterium NMR spectroscopy. The NMR resonances for the deuterium in the six positions in the molecule were well separated and each could be resolved into two or more components as a consequence of the isotopic shifts due to the presence of neighbouring deuterium atoms.

It was possible to determine the fractions of the molecules exchanged on the open side of the ring, on the hindered side (cis to the methyl group) or on both sides. These fractions and other features of the experimental results were used to discuss the mechanisms of the exchange reactions and the manner in which these varied with the metal or with temperature. The highest extents of multiple exchange and of ‘turnover’ of the molecules on the surface were found with palladium.