| Project Detail |
Selective hydroxylation of abundant, but chemically inert C-H bonds remains one of the great challenges in modern chemistry. Given that the resulting alcohols can easily be converted into a variety of other functional groups, this process is key to the large-scale production of commodity chemicals from a natural feedstock. Consequently, developing sustainable and environmentally benign catalysts capable of performing this transformation by utilizing cheap oxidants is of utmost importance. Such catalysts must be reactive enough to overcome the chemical inertness of C-H bonds, yet avoid over-oxidation, and be able to distinguish the target reaction site from other C-H bonds present. Although in recent decades significant progress has been achieved in catalytic hydroxylation of methane and ethane, selective hydroxylation of heavier alkanes (as well as of alkyl chain residues particularly at the terminal position) is still only possible by natural metalloenzymes. While being environment-friendly and functioning under mild conditions, these natural catalysts are poorly applicable to large-scale industrial processes due to their low stability and high cost. Nevertheless, the underlying principles such as (1) reactive metal centers embedded in hydrophobic pockets, (2) structurally defined reaction environment, and (3) affinity-based differentiation between substrates and products, can be capitalized upon for constructing a new generation of synthetic catalysts.
The project will demonstrate how these rationales can be implemented with novel metal-functionalized cavitands – inner cavity containing molecules with a rigid metal-binding site accessible only from their interior. This fresh design combines the oxidative power of high valent metal-oxo species with the chemoselectivity for hydrophobic substrates, necessary to avoid product over-oxidation, while the desired site-selectivity is achieved by a well-defined spatial orientation of the encapsulated substrate molecules. |
