One-Step Photocatalytic Oxidation of Cumene with Mesoporous Carbon Nitride

TL;DR

A metal-free photocatalyst efficiently converts cumene into useful products under mild conditions, offering a sustainable alternative for chemical manufacturing.

Contribution

Introduces mesoporous graphitic carbon nitride as a scalable, metal-free photocatalyst for selective oxidation of benzylic substrates.

Findings

Mesoporous carbon nitride enables selective oxidation of cumene to acetophenone and 1-methoxyethylbenzene with high efficiency.

Hydroperoxide radicals are identified as key intermediates in the oxidation process under oxygen-rich conditions.

The catalyst maintains high performance and durability even after multiple reuse cycles and at larger scales.

Abstract

The shift toward mild, low-impact chemical conversion
is pivotal
for future development. Photocatalytic energy conversion, which harnesses
light to drive reactions under mild conditions, offers a powerful
alternative to conventional energy-intensive synthetic routes. Here,
we establish mesoporous graphitic carbon nitride (mpg-CN) as a highly
efficient, metal-free photocatalyst for the selective oxidation of
benzylic substrates, using cumene as a representative example. Optimized
conditions enabled the selective oxidation of cumene to acetophenone
and 1-methoxyethylbenzene with high efficiency, underscoring the catalyst’s
reaction selectivity and synthetic value. The system readily accommodates
structurally related substrates with radical stability and steric
hindrance playing defining roles in reactivity. Sensitivity analyses
revealed critical parameters governing reaction performance, while
spin-trapping experiments under oxygen-rich conditions identified
hydroperoxide radicals as key intermediates initiating α-carbon
oxidation. Notably, scaling the reaction 10-fold preserved 66% conversion
and 70% selectivity, and a further scale-up to gram scale of precursor
delivered 50% acetophenone after 72 h. Furthemore, solvent recovery
and reuse maintained high catalytic efficiency over the initial reuse
cycles, demonstrating the operational durability of the system. Collectively,
these findings position mpg-CN as a robust, scalable, and metal-free
photocatalyst, a compelling platform for next-generation chemical
manufacturing.

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