Graphene Oxide: Carbocatalyst or Reagent?

Metal-free heterogeneous carbon-based materials have the potential to facilitate a wide range of organic transformations in an economical and environmentally-friendly manner. However, the mechanism of their action is often obfuscated by their ill-defined nature, so careful analysis of the reaction products is essential before they can be labelled "catalysts" in accordance with the IUPAC definition. We present here our findings on the archetypal "carbocatalytic" conversion of benzyl alcohol to benzaldehyde, in which graphene oxide is reduced and a major side product, dibenzyl ether, is also formed. Thus, our work reclassifies graphene oxide as a reagent and presents an important step in the proper evaluation of reactions in the nascent field of carbocatalysis.