Microscale Catalytic Hydrogenation of Cyclopropane with Nanoparticle Palladium

Abstract

Cyclopropane can be hydrogenated to produce propane under moderately high temperatures (∼175 °C). Using a nanoparticle palladium catalyst, undergraduate students can explore the reaction and draw conclusions regarding the conditions for reaction. When deuterium is used, conclusions pertaining to the reaction mechanism are possible. The full complexity of the hydrogen–deuterium exchange equilibrium on the metal surface is indicated by the observation of all nine possible hydrogen–deuterium isotopologues, propane-dx (x = 0–8), as products. To think about the reaction mechanism, the unusual bonding in cyclopropane and its interactions with a metal surface are considered. Differences between cyclopropane and propane in terms of their physical and chemical properties are discussed. The use of this activity as a multisemester research project across all levels of undergraduate students is discussed in terms of logistics, expectations, and outcomes. The catalyst tube consists of nanoparticle palladium beads (0.5%) on alumina, is inexpensive and easy to construct, and lasts indefinitely. Product analysis is by mass spectrometry and 1H NMR spectroscopy. Suggestions are provided for undergraduate exploration and inquiry-based research activities.