Boosting cumene hydrogen transfer via a Ru-based porphyrin covalent organic framework for tandem air epoxidation of olefins

Constructing catalysts featuring an ordered structure, stable performance, and uniformly dispersed catalytic sites is vital for the epoxidation of small-molecular olefins. Here, we design catalysts by tracing the oxidation-process origin and synthesize a series of highly dispersed metal porphyrin-based covalent organic frameworks (COFs) materials. The aim is to efficiently oxidize the C–H bonds of cumene by air to in-situ generate organic peroxides at a safe concentration, and integrate the multi-step oxidation method of cumene in industry into a one-step method for olefins’ epoxidation. The carbonyl-ruthenium COF (Ru-COF-1) exhibits excellent performance, with 98% epoxide selectivity, 1221.77 h⁻¹ productivity, and over 95% selectivity after 9 cycles for 1-hexene. Analysis of structure–properties–catalytic relationships of Ru-COF-1 shows that, compared with Ru-porphyrins and metal-free COFs, the enhanced reaction performance mainly results from Ru metal introduction, which promotes benzylic proton transfer in cumene. Besides, Ru-COF-1’s porous, ordered structure aids oxygen enrichment, forming active peroxy radicals with the cumene carbon-centered radicals formed on the catalyst surface. Ru-H sites then accelerate active oxygen transfer from peroxy radicals, enabling olefin tandem epoxidation. Density functional theory (DFT) calculations verify the reaction mechanism, and this work offers a reference for the design of catalysts for the green, safe, and efficient oxidation of olefins.