Cl ₂⋅ ⁻ Mediates Direct and Selective Conversion of Inert C(sp ³)−H Bonds into Aldehydes/Ketones

Abstract

Developing new reactive pathway to activate inert C(sp ³)−H bonds for valuable oxygenated products remains a challenge. We prepared a series of triazine conjugated organic polymers to photoactivate C−H into aldehyde/ketone via O ₂→H ₂O ₂→⋅OH→Cl⋅→Cl ₂⋅ ⁻. Experiment results showed Cl ₂⋅ ⁻ could successively activate C(sp ³)−H more effectively than Cl⋅ to generate unstable dichlorinated intermediates, increasing the kinetic rate ratio of dichlorination to monochlorination by a factor of 2,000 and thus breaking traditional dichlorination kinetic constraints. These active intermediates were hydrolyzed into aldehydes or ketones easily, when compared with typical stable dichlorinated complexes, avoiding chlorinated by‐product generation. Moreover, an integrated two‐phase system in an acid solution strengthened the Cl ₂⋅ ⁻ mediated process and inhibited product overoxidation, where the conversion rate of toluene reached 16.94 mmol/g/h and the selectivity of benzaldehyde was 99.5 %. This work presents a facile and efficient approach for selective conversion of inert C(sp ³)−H bonds using Cl ₂⋅ ⁻.