Relay catalysis on the surface of hybrid silica functionalized with dual metalloporphyrins(Co&Zn) for efficient and selective oxygenation of cycloalkanes using oxygen

To realize efficient and selective cycloalkanes oxygenation using oxygen, 5-(4-(hydroxyl)phenyl)-10,15,20-tris(chlorophenyl)porphyrin cobalt and 5-(4-(hydroxyl)phenyl)-10,15,20-tris(chlorophenyl)porphyrin zinc were immobilized on the exterior surface of functionalized hybrid silica to construct the relay catalysis system. In the designed catalysis system, the frequent contact of partial oxygenation products (alcohol and ketone) with catalytic active centers were suppressed by heterogeneous catalysis. Relay catalysis between Co and Zn was designed to exploit natural oxidative characteristic of cycloalkyl hydroperoxides to transform more unoxidized substrate. Applied to cycloalkanes oxygenation, not only the excessive oxygenation of partial oxygenation products was suppressed efficiently, but also the substrate conversion and selectivity towards partial oxygenation products were improved concurrently. In cyclohexane oxygenation, the conversion raised from 3.98% to 4.47% with the selectivity raised from 82.3% to 94.4%, which was mainly attributed to the relay catalysis on the surface. To the extent of our understanding, this work not only presented a novel strategy for realizing efficient and selective cycloalkanes oxygenation using oxygen, but also provided a model for other crucial chemical oxygenation processes.