Oligomerization, Isomerization and Carboxylation of Alkanes and Alkenes with Galvanostatically Generated Superoxide in the Al/O2 Electrochemical Cell.

Conversion of low-value, but thermodynamically stable chemical byproducts such as alkanes or CO2 to more valuable feedstocks is of broad-based interest. These so-called up-conversion processes are expensive because they require energy-intensive and catalytic interventions to drive reactions against thermodynamic gradients. Here we show that the nucleophilic characteristics of superoxides, generated galvanostatically in an Aluminum/O2 electrochemical cell, can be used in tandem with the intrinsic catalytic properties of an imidazolium/AlCl3 electrolyte to facilely upgrade alkanes (n-decane), alkenes (1-decene), and CO2 feedstocks. The aluminum/O2 electrochemical cell used to generate the superoxide intermediate is also reported to deliver large amounts of electrical energy and therefore offers a system for high-energy density storage and for chemical up-conversion of low-value compounds. Chronopotentiometry, mass spectrometry and nuclear magnetic resonance were used to investigate the electrochemical features of the system and to analyze the discharge products. We find that even at room temperature, alkanes and alkenes are facilely oligomerized and isomerized at high conversions (>97 %), mimicking the traditionally produced refined products. Incorporating CO2 in the alkane feed leads to formation of esters and formates at moderate yields (21 %).