Production and use of H₂O₂ for atom-efficient functionalization of hydrocarbons and small molecules

H₂O₂ is a relatively benign and selective oxidant, which has motivated research into scalable methods for H₂O₂ production and the design of catalysts to perform oxidations with H₂O₂. The energy intensive anthraquinone oxidation process is the standard for H₂O₂ production, however, alternatives such as electrocatalytic oxygen reduction and the direct synthesis of H₂O₂ have significant potential. Recent publications have investigated the reactor design, the mechanism for H₂O₂ formation, and the synthesis of increasingly selective catalysts and have demonstrated the role of proton-electron transfer in H₂O₂ formation and improving selectivities by alloying transition metals. H₂O₂ is a relatively unstable molecule which readily decomposes over a catalyst, making it difficult to use H₂O₂ for many oxidation reactions selectively. As such, there is extensive research on the use of H₂O₂ for different oxidation reactions, with the most common being olefin epoxidation. Olefin epoxidation is readily catalyzed by transition metal substituted zeolites, polyoxometallates, metal oxides, and homogeneous coordination compounds. These catalysts activate H₂O₂ to form many reactive intermediates, which possess selectivities for the epoxidation of olefins that reflect electronic properties of the reactive intermediate and the substrate. Ideally, H₂O₂ could be used for epoxidations within a single reactor (i.e., tandem catalysis), which would reduce costs from purification and transportation of H₂O₂. However, performing these reactions together typically provides poor epoxidation selectivities due to over-oxidation products. These chemistries are industrially relevant and present many unanswered questions of fundamental interest that warrant future investigation.