Low Energy Electron Induced C–H Activation Reactions in Methane Containing Ices

Abstract

Conversion of alkanes to functionalized compounds is a highly sought after goal. Under high reaction temperatures, desired intermediate products like alcohols, aldehydes, and carboxylic acids are more easily oxidized to CO2 than the starting alkane, which makes it difficult to recover these functionalized compounds. Here, we use electrons with energy <20 eV to initiate reactions in pure methane and mixed layers of methane and oxygen condensed on a gold substrate at 15 K. Observation of ethane (in pure and mixed films) and methanol and formaldehyde (in mixed films) indicates methane activation by electrons. From the formation threshold and energy dependence of product yields, electronic excitation of reactant/s followed by dissociation into neutral radicals appears to be the reaction initiating step. The results demonstrate the utility of low energy electrons in bringing about functionalization in the simplest alkane.